Honors & Awards

  • Carol and Doug Kimmelman Scholar, Stanford University (2021)
  • Pape Family Pilot Award, Rivkin Center for Ovarian Cancer Research (2016)
  • Research Award, Mary Kay Foundation (2016)
  • Ovarian Cancer Academy Award, Department of Defense (2015)
  • Gabilan Faculty Award, Stanford University (2014-2016)
  • J. Martin Brown Award for Outstanding Achievements in the Radiation Sciences, Stanford University (2012)
  • Postdoctoral Trainee Award, NCI (2007-2012)
  • Saul Winegrad Award for Outstanding Dissertation, University of Pennsylvania (2007)

Professional Education

  • BS, University of Illinois Urbana-Champaign, Microbiology (2000)
  • PhD, University of Pennsylvania, Cellular and Molecular Biology (2007)

All Publications

  • Exploring deep learning for estimating the isoeffective dose of FLASH irradiation from mouse intestinal histology images. International journal of radiation oncology, biology, physics Fu, J., Yang, Z., Melemenidis, S., Viswanathan, V., Dutt, S., Manjappa, R., Lau, B., Soto, L. A., Ashraf, R., Skinner, L., Yu, S. J., Surucu, M., Casey, K. M., Rankin, E. B., Graves, E., Lu, W., Loo, B. W., Gu, X. 2024


    Ultra-high dose rate (FLASH) irradiation has been reported to reduce normal tissue damage compared with conventional dose rate (CONV) irradiation without compromising tumor control. This proof-of-concept study aims to develop a deep learning (DL) approach to quantify the FLASH isoeffective dose (dose of CONV that would be required to produce the same effect as the given physical FLASH dose) with post-irradiation mouse intestinal histological images.84 healthy C57BL/6J female mice underwent 16 MeV electron CONV (0.12Gy/s; n=41) or FLASH (200Gy/s; n=43) single fraction whole abdominal irradiation. Physical dose ranged from 12 to 16Gy for FLASH and 11 to 15Gy for CONV in 1Gy increments. 4 days after irradiation, 9 jejunum cross-sections from each mouse were H&E stained and digitized for histological analysis. CONV dataset was randomly split into training (n=33) and testing (n=8) datasets. ResNet101-based DL models were retrained using the CONV training dataset to estimate the dose based on histological features. The classical manual crypt counting (CC) approach was implemented for model comparison. Cross-section-wise mean squared error (CS-MSE) was computed to evaluate the dose estimation accuracy of both approaches. The validated DL model was applied to the FLASH dataset to map the physical FLASH dose into the isoeffective dose.The DL model achieved a CS-MSE of 0.20Gy2 on the CONV testing dataset compared with 0.40Gy2 of the CC approach. Isoeffective doses estimated by the DL model for FLASH doses of 12, 13, 14, 15, and 16 Gy were 12.19±0.46, 12.54±0.37, 12.69±0.26, 12.84±0.26, and 13.03±0.28 Gy, respectively.Our proposed DL model achieved accurate CONV dose estimation. The DL model results indicate that in the physical dose range of 13 to 16 Gy, the biological dose response of small intestinal tissue to FLASH irradiation is represented by a lower isoeffective dose compared to the physical dose. Our DL approach can be a tool for studying isoeffective doses of other radiation dose modifying interventions.

    View details for DOI 10.1016/j.ijrobp.2023.12.032

    View details for PubMedID 38171387

  • Therapeutic targeting of the functionally elusive TAM receptor family. Nature reviews. Drug discovery Miao, Y. R., Rankin, E. B., Giaccia, A. J. 2023


    The TAM receptor family of TYRO3, AXL and MERTK regulates tissue and immune homeostasis. Aberrant TAM receptor signalling has been linked to a range of diseases, including cancer, fibrosis and viral infections. Specifically, the dysregulation of TAM receptors can enhance tumour growth and metastasis due to their involvement in multiple oncogenic pathways. For example, TAM receptors have been implicated in the epithelial-mesenchymal transition, maintaining the stem cell phenotype, immune modulation, proliferation, angiogenesis and resistance to conventional and targeted therapies. Therapeutically, multiple TAM receptor inhibitors are in preclinical and clinical development for cancers and other indications, with those targeting AXL being the most clinically advanced. Although there has been notable clinical advancement in recent years, challenges persist. This Review aims to provide both biological and clinical insights into the current therapeutic landscape of TAM receptor inhibitors, and evaluates their potential for the treatment of cancer and non-malignant diseases.

    View details for DOI 10.1038/s41573-023-00846-8

    View details for PubMedID 38092952

  • Serine starvation silences estrogen receptor signaling through histone hypoacetylation. Proceedings of the National Academy of Sciences of the United States of America Li, A. M., He, B., Karagiannis, D., Li, Y., Jiang, H., Srinivasan, P., Ramirez, Y., Zhou, M. N., Curtis, C., Gruber, J. J., Lu, C., Rankin, E. B., Ye, J. 2023; 120 (38): e2302489120


    Loss of estrogen receptor (ER) pathway activity promotes breast cancer progression, yet how this occurs remains poorly understood. Here, we show that serine starvation, a metabolic stress often found in breast cancer, represses estrogen receptor alpha (ERα) signaling by reprogramming glucose metabolism and epigenetics. Using isotope tracing and time-resolved metabolomic analyses, we demonstrate that serine is required to maintain glucose flux through glycolysis and the TCA cycle to support acetyl-CoA generation for histone acetylation. Consequently, limiting serine depletes histone H3 lysine 27 acetylation (H3K27ac), particularly at the promoter region of ER pathway genes including the gene encoding ERα, ESR1. Mechanistically, serine starvation impairs acetyl-CoA-dependent gene expression by inhibiting the entry of glycolytic carbon into the TCA cycle and down-regulating the mitochondrial citrate exporter SLC25A1, a critical enzyme in the production of nucleocytosolic acetyl-CoA from glucose. Consistent with this model, total H3K27ac and ERα expression are suppressed by SLC25A1 inhibition and restored by acetate, an alternate source of acetyl-CoA, in serine-free conditions. We thus uncover an unexpected role for serine in sustaining ER signaling through the regulation of acetyl-CoA metabolism.

    View details for DOI 10.1073/pnas.2302489120

    View details for PubMedID 37695911

  • Human enteroids as a tool to study conventional and ultra-high dose rate radiation. Integrative biology : quantitative biosciences from nano to macro Klett, K. C., Martin-Villa, B. C., Villarreal, V. S., Melemenidis, S., Viswanathan, V., Manjappa, R., Ashraf, M. R., Soto, L., Lau, B., Dutt, S., Rankin, E. B., Loo, B. W., Heilshorn, S. C. 2023; 15


    Radiation therapy, one of the most effective therapies to treat cancer, is highly toxic to healthy tissue. The delivery of radiation at ultra-high dose rates, FLASH radiation therapy (FLASH), has been shown to maintain therapeutic anti-tumor efficacy while sparing normal tissues compared to conventional dose rate irradiation (CONV). Though promising, these studies have been limited mainly to murine models. Here, we leveraged enteroids, three-dimensional cell clusters that mimic the intestine, to study human-specific tissue response to radiation. We observed enteroids have a greater colony growth potential following FLASH compared with CONV. In addition, the enteroids that reformed following FLASH more frequently exhibited proper intestinal polarity. While we did not observe differences in enteroid damage across groups, we did see distinct transcriptomic changes. Specifically, the FLASH enteroids upregulated the expression of genes associated with the WNT-family, cell-cell adhesion, and hypoxia response. These studies validate human enteroids as a model to investigate FLASH and provide further evidence supporting clinical study of this therapy. Insight Box Promising work has been done to demonstrate the potential of ultra-high dose rate radiation (FLASH) to ablate cancerous tissue, while preserving healthy tissue. While encouraging, these findings have been primarily observed using pre-clinical murine and traditional two-dimensional cell culture. This study validates the use of human enteroids as a tool to investigate human-specific tissue response to FLASH. Specifically, the work described demonstrates the ability of enteroids to recapitulate previous in vivo findings, while also providing a lens through which to probe cellular and molecular-level responses to FLASH. The human enteroids described herein offer a powerful model that can be used to probe the underlying mechanisms of FLASH in future studies.

    View details for DOI 10.1093/intbio/zyad013

    View details for PubMedID 37874173

  • Mitochondrial uncoupling induces epigenome remodeling and promotes differentiation in neuroblastoma. Cancer research Jiang, H., Greathouse, R. L., Tiche, S. J., Zhao, M., He, B., Li, Y., Li, A. M., Forgo, B., Yip, M., Li, A., Shih, M., Banuelos, S., Zhou, M., Gruber, J. J., Rankin, E. B., Hu, Z., Shimada, H., Chiu, B., Ye, J. 2022


    The Warburg effect is the major metabolic hallmark of cancer. According to Warburg himself, the consequence of the Warburg effect is cell dedifferentiation. Therefore, reversing the Warburg effect might be an approach to restore cell differentiation in cancer. In this study, we used a mitochondrial uncoupler, niclosamide ethanolamine (NEN), to activate mitochondrial respiration, which induced neural differentiation in neuroblastoma cells. NEN treatment increased the nicotinamide adenine dinucleotide (NAD)+/NADH and pyruvate/lactate ratios and also the alpha-ketoglutarate (alpha-KG)/2- hydroxyglutarate (2-HG) ratio. Consequently, NEN treatment induced promoter CpG island demethylation and epigenetic landscape remodeling, activating the neural differentiation program. In addition, NEN treatment upregulated p53 but downregulated N-Myc and beta-catenin signaling in neuroblastoma cells. Importantly, even under hypoxia, NEN treatment remained effective in inhibiting 2-HG generation, promoting DNA demethylation, and suppressing hypoxia-inducible factor signaling. Dietary NEN intervention reduced tumor growth rate, 2-HG levels, and expression of N-Myc and beta-catenin in tumors in an orthotopic neuroblastoma mouse model. Integrative analysis indicated that NEN treatment upregulated favorable prognosis genes and downregulated unfavorable prognosis genes, which were defined using multiple neuroblastoma patient datasets. Altogether, these results suggest that mitochondrial uncoupling is an effective metabolic and epigenetic therapy for reversing the Warburg effect and inducing differentiation in neuroblastoma.

    View details for DOI 10.1158/0008-5472.CAN-22-1029

    View details for PubMedID 36318118

  • The controversial role and therapeutic development of the m6A demethylase FTO in renal cell carcinoma. Translational oncology Zhang, D., Wornow, S., Peehl, D. M., Rankin, E. B., Brooks, J. D. 2022; 25: 101518


    Fat mass and obesity-associated (FTO) protein, the first m6A demethylase identified in 2011, regulates multiple aspects of RNA biology including splicing, localization, stability, and translation. Accumulating data show that FTO is involved in numerous physiological processes and is implicated in multiple cancers including renal cell carcinoma (RCC). However, the exact role of FTO in RCC remains controversial. Some studies demonstrated that decreased FTO expression was associated with aggressive clinical features and shorter overall survival in clear cell RCC (ccRCC) patients, while others found that FTO inhibition selectively reduced the growth and survival of VHL-deficient ccRCC cells in vitro and in vivo. Here, we review the evidence supporting either a promoting or suppressive role of FTO in kidney cancers, the mechanisms of action of FTO, and recent progress in developing FTO inhibitors.

    View details for DOI 10.1016/j.tranon.2022.101518

    View details for PubMedID 36037557

  • Serine starvation silences estrogen receptor signaling through histone hypoacetylation Li, A. M., Li, Y., He, B., Jiang, H., Lu, C., Gruber, J. J., Rankin, E. B., Ye, J. AMER ASSOC CANCER RESEARCH. 2022
  • Loss of parathyroid hormone receptor signaling in osteoprogenitors is associated with accumulation of multiple hematopoietic lineages in the bone marrow. Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research Kimura, T., Panaroni, C., Rankin, E. B., Purton, L. E., Wu, J. Y. 2022


    Osteoblasts and their progenitors play an important role in the support of hematopoiesis within the bone marrow microenvironment. We have previously reported that parathyroid hormone receptor (PTH1R) signaling in osteoprogenitors is required for normal B cell precursor differentiation, and for trafficking of maturing B cells out of the bone marrow. Cells of the osteoblast lineage have been implicated in the regulation of several other hematopoietic cell populations, but the effects of PTH1R signaling in osteoprogenitors on other maturing hematopoietic populations have not been investigated. Here we report that numbers of maturing myeloid, T cell, and erythroid populations were increased in the bone marrow of mice lacking PTH1R in osteoprogenitors (PTH1R-OsxKO mice). This increase in maturing hematopoietic populations was not associated with an increase in progenitor populations or proliferation. The spleens of PTH1R-OsxKO mice were small with decreased numbers of all hematopoietic populations, suggesting that trafficking of mature hematopoietic populations between bone marrow and spleen is impaired in the absence of PTH1R in osteoprogenitors. RNA sequencing of osteoprogenitors and their descendants in bone and bone marrow revealed increased expression of VCAM-1 and CXCL12, factors that are involved in trafficking of several hematopoietic populations.

    View details for DOI 10.1002/jbmr.4568

    View details for PubMedID 35490308

  • Abdominopelvic FLASH Irradiation Improves PD-1 Immune Checkpoint Inhibition in Preclinical Models of Ovarian Cancer. Molecular cancer therapeutics Eggold, J. T., Chow, S., Melemenidis, S., Wang, J., Natarajan, S., Loo, P. E., Manjappa, R., Viswanathan, V., Kidd, E. A., Engleman, E., Dorigo, O., Loo, B. W., Rankin, E. B. 2021


    Treatment of advanced ovarian cancer using PD-1/PD-L1 immune checkpoint blockade shows promise, however current clinical trials are limited by modest response rates. Radiation therapy has been shown to synergize with PD-1/PD-L1 blockade in some cancers but has not been utilized in advanced ovarian cancer due to toxicity associated with conventional abdominopelvic irradiation. While ultra-high dose rate (FLASH) irradiation has emerged as a strategy to reduce radiation-induced toxicity, the immunomodulatory properties of FLASH irradiation remain unknown. Here we demonstrate that single high dose abdominopelvic FLASH irradiation promoted intestinal regeneration and maintained tumor control in a preclinical mouse model of ovarian cancer. Reduced tumor burden in conventional and FLASH treated mice was associated with an early decrease in intratumoral regulatory T cells and a late increase in cytolytic CD8+ T cells. Compared to conventional irradiation, FLASH irradiation increased intratumoral T cell infiltration at early timepoints. Moreover, FLASH irradiation maintained the ability to increase intratumoral CD8+ T cell infiltration and enhance the efficacy of alphaPD-1 therapy in preclinical models of ovarian cancer. These data highlight the potential for FLASH irradiation to improve the therapeutic efficacy of checkpoint inhibition in the treatment of ovarian cancer.

    View details for DOI 10.1158/1535-7163.MCT-21-0358

    View details for PubMedID 34866044

  • GAS6/AXL inhibition enhances ovarian cancer sensitivity to chemotherapy and PARP inhibition through increased DNA damage and enhanced replication stress. Molecular cancer research : MCR Mullen, M. M., Lomonosova, E., Toboni, M. D., Oplt, A., Cybulla, E., Blachut, B., Zhao, P., Noia, H., Wilke, D., Rankin, E. B., Kuroki, L. M., Hagemann, A. R., Hagemann, I. S., McCourt, C. K., Thaker, P. H., Mutch, D. G., Powell, M. A., Mosammaparast, N., Vindigni, A., Fuh, K. C. 2021


    Over 80% of women with high-grade serous ovarian cancer develop tumor resistance to chemotherapy and die of their disease. There are currently no FDA-approved agents to improve sensitivity to first-line platinum- and taxane-based chemotherapy or to poly (ADP-ribose) polymerase (PARP) inhibitors. Here, we tested the hypothesis that expression of growth arrest-specific 6 (GAS6), the ligand of receptor tyrosine kinase AXL, is associated with chemotherapy response and that sequestration of GAS6 with AVB-S6-500 (AVB-500) could improve tumor response to chemotherapy and PARP inhibitors. We found that GAS6 levels in patient tumor and serum samples collected before chemotherapy correlated with ovarian cancer chemoresponse and patient survival. Compared to chemotherapy alone, AVB-500 plus carboplatin and/or paclitaxel led to decreased ovarian cancer cell survival in vitro and tumor burden in vivo. Cells treated with AVB-500 plus carboplatin had more DNA damage, slower DNA replication fork progression, and fewer RAD51 foci than cells treated with carboplatin alone, indicating AVB-500 impaired homologous recombination. Finally, treatment with the PARP inhibitor olaparib plus AVB-500 led to decreased ovarian cancer cell survival in vitro and less tumor burden in vivo. Importantly, this effect was seen in homologous recombination-proficient and homologous recombination-deficient ovarian cancer cells. Collectively, our findings suggest that GAS6 levels could be used to predict response to carboplatin and AVB-500 could be used to treat platinum-resistant, homologous recombination-proficient high-grade serous ovarian cancer. Implications: GAS6/AXL is a novel target to sensitize ovarian cancers to carboplatin and olaparib. Additionally, GAS6 levels can be associated with response to carboplatin treatment.

    View details for DOI 10.1158/1541-7786.MCR-21-0302

    View details for PubMedID 34670865

  • Cancer-associated mesothelial cells promote ovarian cancer chemoresistance through paracrine osteopontin signaling. The Journal of clinical investigation Qian, J., LeSavage, B. L., Hubka, K. M., Ma, C., Natarajan, S., Eggold, J. T., Xiao, Y., Fuh, K. C., Krishnan, V., Enejder, A., Heilshorn, S. C., Dorigo, O., Rankin, E. B. 2021; 131 (16)


    Ovarian cancer is the leading cause of gynecological malignancy-related deaths, due to its widespread intraperitoneal metastases and acquired chemoresistance. Mesothelial cells are an important cellular component of the ovarian cancer microenvironment that promote metastasis. However, their role in chemoresistance is unclear. Here, we investigated whether cancer-associated mesothelial cells promote ovarian cancer chemoresistance and stemness in vitro and in vivo. We found that osteopontin is a key secreted factor that drives mesothelial-mediated ovarian cancer chemoresistance and stemness. Osteopontin is a secreted glycoprotein that is clinically associated with poor prognosis and chemoresistance in ovarian cancer. Mechanistically, ovarian cancer cells induced osteopontin expression and secretion by mesothelial cells through TGF-beta signaling. Osteopontin facilitated ovarian cancer cell chemoresistance via the activation of the CD44 receptor, PI3K/AKT signaling, and ABC drug efflux transporter activity. Importantly, therapeutic inhibition of osteopontin markedly improved the efficacy of cisplatin in both human and mouse ovarian tumor xenografts. Collectively, our results highlight mesothelial cells as a key driver of ovarian cancer chemoresistance and suggest that therapeutic targeting of osteopontin may be an effective strategy for enhancing platinum sensitivity in ovarian cancer.

    View details for DOI 10.1172/JCI146186

    View details for PubMedID 34396988

  • GAS6 inhibition induces platinum sensitivity through increased replication stress in ovarian cancer Mullen, M., Lomonosova, E., Toboni, M., Oplt, A., Cybulla, E., Blachut, B., Noia, H., Wilke, D., Rankin, E., Kuroki, L., Hagemann, A., Hagemann, I., McCourt, C., Thaker, P., Mutch, D., Powell, M., Vindigni, A., Fuh, K. ACADEMIC PRESS INC ELSEVIER SCIENCE. 2021: S40
  • Eliminating hypoxic tumor cells improves response to PARP inhibitors in homologous recombination-deficient cancer models. The Journal of clinical investigation Mehibel, M., Xu, Y., Li, C. G., Moon, E. J., Thakkar, K. N., Diep, A. N., Kim, R. K., Bloomstein, J. D., Xiao, Y., Bacal, J., Saldivar, J. C., Le, Q., Cimprich, K. A., Rankin, E. B., Giaccia, A. J. 2021; 131 (11)


    Hypoxia, a hallmark feature of the tumor microenvironment, causes resistance to conventional chemotherapy, but was recently reported to synergize with poly(ADP-ribose) polymerase inhibitors (PARPis) in homologous recombination-proficient (HR-proficient) cells through suppression of HR. While this synergistic killing occurs under severe hypoxia (<0.5% oxygen), our study shows that moderate hypoxia (2% oxygen) instead promotes PARPi resistance in both HR-proficient and -deficient cancer cells. Mechanistically, we identify reduced ROS-induced DNA damage as the cause for the observed resistance. To determine the contribution of hypoxia to PARPi resistance in tumors, we used the hypoxic cytotoxin tirapazamine to selectively kill hypoxic tumor cells. We found that the selective elimination of hypoxic tumor cells led to a substantial antitumor response when used with PARPi compared with that in tumors treated with PARPi alone, without enhancing normal tissue toxicity. Since human breast cancers with BRAC1/2 mutations have an increased hypoxia signature and hypoxia reduces the efficacy of PARPi, then eliminating hypoxic tumor cells should enhance the efficacy of PARPi therapy.

    View details for DOI 10.1172/JCI146256

    View details for PubMedID 34060485

  • Eliminating hypoxic tumor cells improves response to PARP inhibitors in homologous recombination & ndash;deficient cancer models JOURNAL OF CLINICAL INVESTIGATION Mehibel, M., Xu, Y., Li, C. G., Moon, E., Thakkar, K. N., Diep, A. N., Kim, R. K., Bloomstein, J. D., Xiao, Y., Bacal, J., Saldivar, J. C., Le, Q., Cimprich, K. A., Rankin, E. B., Giaccia, A. J. 2021; 131 (11)

    View details for DOI 10.1172/JCI146256.

    View details for Web of Science ID 000656969100004

  • Neutralization of PD-L2 is Essential for Overcoming Immune Checkpoint Blockade Resistance in Ovarian Cancer. Clinical cancer research : an official journal of the American Association for Cancer Research Miao, Y. R., Thakkar, K. N., Qian, J., Kariolis, M. S., Huang, W., Nandagopal, S., Yang, T. T., Diep, A. N., Cherf, G. M., Xu, Y., Moon, E. J., Xiao, Y., Alemany, H., Li, T., Yu, W., Wei, B., Rankin, E. B., Giaccia, A. J. 2021


    PURPOSE: Ovarian cancer represents a major clinical hurdle for immune checkpoint blockade (ICB), with reported low patient response rates. We found that the immune checkpoint ligand PD-L2 is robustly expressed in patient samples of ovarian cancers and other malignancies exhibiting suboptimal response to ICB but not in cancers that are ICB sensitive. Therefore we hypothesize that PD-L2 can facilitate immune escape from ICB through incomplete blockade of the PD-1 signaling pathway.EXPERIMENTAL DESIGN: We engineered a soluble form of the PD-1 receptor (sPD-1) capable of binding and neutralizing both PD-L2 and PD-L1 with x200 and x10,000 folds improvement in binding affinity over wild-type PD-1. Leading to superior inhibition of ligand-mediated PD-1 activities.RESULTS: Both In vitro and in vivo analyses performed in this study demonstrated that the high-affinity sPD-1 molecule is superior at blocking both PD-L1 and PD-L2 mediated immune evasion and reducing tumor growth in immune-competent murine models of ovarian cancer.CONCLUSIONS: The data presented in this study provides justification for using a dual targeting, high-affinity sPD-1 receptor as an alternative to PD-1 or PD-L1 therapeutic antibodies for achieving superior therapeutic efficacy in cancers expressing both PD-L2 and PD-L1.

    View details for DOI 10.1158/1078-0432.CCR-20-0482

    View details for PubMedID 34011561

  • -003 Oxygen dependent resistance to PARP inhibitors Mehibel, M., Xu, J., Li, G., Moon, J., Thakkar, K., Diep, A., Kim, R., Blomstein, J., Xiao, S., Bacal, J., Saldivar, J., Le, Q., Cimprich, K., Rankin, E., Giaccia, A. AMER ASSOC CANCER RESEARCH. 2021
  • Omental macrophages secrete chemokine ligands that promote ovarian cancer colonization of the omentum via CCR1. Communications biology Krishnan, V., Tallapragada, S., Schaar, B., Kamat, K., Chanana, A. M., Zhang, Y., Patel, S., Parkash, V., Rinker-Schaeffer, C., Folkins, A. K., Rankin, E. B., Dorigo, O. 2020; 3 (1): 524


    The omentum is the most common site of ovarian cancer metastasis. Immune cell clusters called milky spots are found throughout the omentum. It is however unknown if these immune cells contribute to ovarian cancer metastasis. Here we report that omental macrophages promote the migration and colonization of ovarian cancer cells to the omentum through the secretion of chemokine ligands that interact with chemokine receptor 1 (CCR1). We found that depletion of macrophages reduces ovarian cancer colonization of the omentum. RNA-sequencing of macrophages isolated from mouse omentum and mesenteric adipose tissue revealed a specific enrichment of chemokine ligandCCL6 in omental macrophages. CCL6 and the human homolog CCL23 were both necessary and sufficient to promote ovarian cancer migration by activating ERK1/2 and PI3K pathways. Importantly, inhibition of CCR1 reduced ovarian cancer colonization. These findings demonstrate a critical mechanism of omental macrophage induced colonization by ovarian cancer cells via CCR1 signaling.

    View details for DOI 10.1038/s42003-020-01246-z

    View details for PubMedID 32963283

  • FLASH irradiation enhances the therapeutic index of abdominal radiotherapy in mice Natarajan, S., Levy, K., Wang, J., Chow, S., Eggold, J., Loo, P., Manjappa, R., Lartey, F. M., Schuler, E., Skinner, L., Rafat, M., Ko, R., Kim, A., Al Rawi, D., von Eyben, R., Dorigo, O., Casey, K. M., Graves, E. E., Bush, K., Yu, A. S., Koong, A. C., Maxim, P. G., Loo, B. W., Rankin, E. B. AMER ASSOC CANCER RESEARCH. 2020
  • Reprogramming of serine metabolism during breast cancer progression Li, A., Ducker, G. S., Li, Y., Seoane, J. A., Xiao, Y., Melemenidis, S., Zhou, Y., Liu, L., Vanharanta, S., Graves, E. E., Rankin, E. B., Curtis, C., Massague, J., Rabinowitz, J. D., Thompson, C. B., Ye, J. AMER ASSOC CANCER RESEARCH. 2020
  • Total abdominal ultra-rapid FLASH irradiation enhances the efficacy of PD-1 inhibition in preclinical models of ovarian cancer Chow, S., Eggold, J. T., Levy, K., Wang, J., Manjappa, R., Breitkreutz, D. Y., Yu, A. S., Bush, K., Dorigo, O., Loo, B. W., Rankin, E. B. AMER ASSOC CANCER RESEARCH. 2020
  • Ultrarapid total abdominal FLASH irradiation in a preclinical model of ovarian cancer. Levy, K., Wang, J., Eggold, J., Natarajan, S., Maxim, P., Loo, B., Rankin, E. AMER ASSOC CANCER RESEARCH. 2020: 49
  • Validated limited gene predictor for cervical cancer lymph node metastases. Oncotarget Bloomstein, J. D., von Eyben, R., Chan, A., Rankin, E. B., Fregoso, D. R., Wang-Chiang, J., Lee, L., Xie, L., David, S. M., Stehr, H., Esfahani, M. S., Giaccia, A. J., Kidd, E. A. 2020; 11 (24): 2302–9


    PURPOSE: Recognizing the prognostic significance of lymph node (LN) involvement for cervical cancer, we aimed to identify genes that are differentially expressed in LN+ versus LN- cervical cancer and to potentially create a validated predictive gene signature for LN involvement.MATERIALS AND METHODS: Primary tumor biopsies were collected from 74 cervical cancer patients. RNA was extracted and RNA sequencing was performed. The samples were divided by institution into a training set (n = 57) and a testing set (n = 17). Differentially expressed genes were identified among the training cohort and used to train a Random Forest classifier.RESULTS: 22 genes showed > 1.5 fold difference in expression between the LN+ and LN- groups. Using forward selection 5 genes were identified and, based on the clinical knowledge of these genes and testing of the different combinations, a 2-gene Random Forest model of BIRC3 and CD300LG was developed. The classification accuracy of lymph node (LN) status on the test set was 88.2%, with an Area under the Receiver Operating Characteristic curve (ROC-AUC) of 98.6%.CONCLUSIONS: We identified a 2 gene Random Forest model of BIRC3 and CD300LG that predicted lymph node involvement in a validation cohort. This validated model, following testing in additional cohorts, could be used to create a reverse transcription-quantitative polymerase chain reaction (RT-qPCR) tool that would be useful for helping to identify patients with LN involvement in resource-limited settings.

    View details for DOI 10.18632/oncotarget.27632

    View details for PubMedID 32595829

  • Induced tumor heterogeneity reveals factors informing radiation and immunotherapy combinations. Clinical cancer research : an official journal of the American Association for Cancer Research Aguilera, T. A., Elghonaimy, E., Shehade, H., Rafat, M., Castellini, L., Jiang, D., Kariolis, M., Koong, A., Le, Q., Ellies, L. G., Rankin, E. B., Graves, E. E., Giaccia, A. J. 2020


    PURPOSE: To investigate how induced tumor heterogeneity influences immune responses to radiotherapy (RT) with different proportions of mixed immune responsive and unresponsive tumor cells in a triple negative breast cancer model. It is hypothesized that studying the immune environment of mixed tumors and responses to RT could nominate immune active therapies to enhance immune responses after RT.EXPERIMENTAL DESIGN: Evaluate efficacy and immune responses generated by RT in tumors with different proportions of immunologically responsive and unresponsive tumor cells. Then study the cellular responses and transcriptomic differences between the tumors to nominate immunotherapy combinations with RT and evaluate the combination.RESULTS: The addition of the responsive cells to unresponsive tumors led to a greater than expected therapeutic response to RT with both innate and adaptive immune components. There was a distinct change in myeloid cells, greater inflammatory macrophage activity, and enhanced antigen presentation with responsive cells after RT. Since differences in matrix components, cell adhesion biology, and innate immune signaling correlated with myeloid cell response and phenotype, we hypothesized that RT combined with CD40 agonist antibody would sensitize unresponsive tumors. The combination therapy resulted improved innate and adaptive immune response. Importantly, CD40 treatment increased tumor response to RT and protected against metastatic spread in a metastatic model.CONCLUSIONS: These data combined with transcriptomics from human patients supports RT and myeloid cell targeting for immunologically cold tumors and presents opportunities to investigate the complex overlapping biologic mechanisms that limit immunotherapy and to implement RT with different immunotherapy combinations.

    View details for DOI 10.1158/1078-0432.CCR-19-4220

    View details for PubMedID 32098769

  • Abdominal FLASH irradiation reduces radiation-induced gastrointestinal toxicity for the treatment of ovarian cancer in mice. Scientific reports Levy, K. n., Natarajan, S. n., Wang, J. n., Chow, S. n., Eggold, J. T., Loo, P. E., Manjappa, R. n., Melemenidis, S. n., Lartey, F. M., Schüler, E. n., Skinner, L. n., Rafat, M. n., Ko, R. n., Kim, A. n., H Al-Rawi, D. n., von Eyben, R. n., Dorigo, O. n., Casey, K. M., Graves, E. E., Bush, K. n., Yu, A. S., Koong, A. C., Maxim, P. G., Loo, B. W., Rankin, E. B. 2020; 10 (1): 21600


    Radiation therapy is the most effective cytotoxic therapy for localized tumors. However, normal tissue toxicity limits the radiation dose and the curative potential of radiation therapy when treating larger target volumes. In particular, the highly radiosensitive intestine limits the use of radiation for patients with intra-abdominal tumors. In metastatic ovarian cancer, total abdominal irradiation (TAI) was used as an effective postsurgical adjuvant therapy in the management of abdominal metastases. However, TAI fell out of favor due to high toxicity of the intestine. Here we utilized an innovative preclinical irradiation platform to compare the safety and efficacy of TAI ultra-high dose rate FLASH irradiation to conventional dose rate (CONV) irradiation in mice. We demonstrate that single high dose TAI-FLASH produced less mortality from gastrointestinal syndrome, spared gut function and epithelial integrity, and spared cell death in crypt base columnar cells compared to TAI-CONV irradiation. Importantly, TAI-FLASH and TAI-CONV irradiation had similar efficacy in reducing tumor burden while improving intestinal function in a preclinical model of ovarian cancer metastasis. These findings suggest that FLASH irradiation may be an effective strategy to enhance the therapeutic index of abdominal radiotherapy, with potential application to metastatic ovarian cancer.

    View details for DOI 10.1038/s41598-020-78017-7

    View details for PubMedID 33303827

  • Evaluating the Reproducibility of Mouse Anatomy under Rotation in a Custom Immobilization Device for Conformal FLASH Radiotherapy. Radiation research Ko, R. B., Soto, L. A., von Eyben, R. n., Melemenidis, S. n., Rankin, E. B., Maxim, P. G., Graves, E. E., Loo, B. W. 2020


    The observation of an enhanced therapeutic index for FLASH radiotherapy in mice has created interest in practical laboratory-based FLASH irradiators. To date, systems capable of 3D conformal FLASH irradiation in mice have been lacking. We are developing such a system, incorporating a high-current linear accelerator to produce a collimated X-ray beam in a stationary beamline design, rotating the mouse about a longitudinal axis to achieve conformal irradiation from multiple beam directions. The purpose of this work was to evaluate the reproducibility of mouse anatomy under rotation at speeds compatible with conformal FLASH delivery. Three short-hair mice and two hairless mice were immobilized under anesthesia in body weight-specific contoured plastic molds, and subjected to three rotational (up to 3 revolutions/s) and two non-rotational movement interventions. MicroCT images were acquired before and after each intervention. The displacements of 11 anatomic landmarks were measured on the image pairs. The displacement of the anatomical landmarks with any of the interventions was 0.5 mm or less for 92.4% of measurements, with a single measurement out of 275 (11 landmarks × 5 interventions × 5 mice) reaching 1 mm. There was no significant difference in the displacements associated with rotation compared to those associated with moving the immobilized mouse in and out of a scanner or with leaving the mouse in place for 5 min with no motion. There were no significant differences in displacements between mice with or without hair, although the analysis is limited by small numbers, or between different anatomic landmarks. These results show that anatomic reproducibility under rotation speed corresponding to FLASH irradiation times appears to be compatible with conformal/stereotactic irradiation in mice.

    View details for DOI 10.1667/RADE-20-00095

    View details for PubMedID 32857849

  • The m6A RNA demethylase FTO is a HIF-independent synthetic lethal partner with the VHL tumor suppressor. Proceedings of the National Academy of Sciences of the United States of America Xiao, Y. n., Thakkar, K. N., Zhao, H. n., Broughton, J. n., Li, Y. n., Seoane, J. A., Diep, A. N., Metzner, T. J., von Eyben, R. n., Dill, D. L., Brooks, J. D., Curtis, C. n., Leppert, J. T., Ye, J. n., Peehl, D. M., Giaccia, A. J., Sinha, S. n., Rankin, E. B. 2020


    Loss of the von Hippel-Lindau (VHL) tumor suppressor is a hallmark feature of renal clear cell carcinoma. VHL inactivation results in the constitutive activation of the hypoxia-inducible factors (HIFs) HIF-1 and HIF-2 and their downstream targets, including the proangiogenic factors VEGF and PDGF. However, antiangiogenic agents and HIF-2 inhibitors have limited efficacy in cancer therapy due to the development of resistance. Here we employed an innovative computational platform, Mining of Synthetic Lethals (MiSL), to identify synthetic lethal interactions with the loss of VHL through analysis of primary tumor genomic and transcriptomic data. Using this approach, we identified a synthetic lethal interaction between VHL and the m6A RNA demethylase FTO in renal cell carcinoma. MiSL identified FTO as a synthetic lethal partner of VHL because deletions of FTO are mutually exclusive with VHL loss in pan cancer datasets. Moreover, FTO expression is increased in VHL-deficient ccRCC tumors compared to normal adjacent tissue. Genetic inactivation of FTO using multiple orthogonal approaches revealed that FTO inhibition selectively reduces the growth and survival of VHL-deficient cells in vitro and in vivo. Notably, FTO inhibition reduced the survival of both HIF wild type and HIF-deficient tumors, identifying FTO as an HIF-independent vulnerability of VHL-deficient cancers. Integrated analysis of transcriptome-wide m6A-seq and mRNA-seq analysis identified the glutamine transporter SLC1A5 as an FTO target that promotes metabolic reprogramming and survival of VHL-deficient ccRCC cells. These findings identify FTO as a potential HIF-independent therapeutic target for the treatment of VHL-deficient renal cell carcinoma.

    View details for DOI 10.1073/pnas.2000516117

    View details for PubMedID 32817424

  • Metabolic Profiling Reveals a Dependency of Human Metastatic Breast Cancer on Mitochondrial Serine and One-Carbon Unit Metabolism. Molecular cancer research : MCR Li, A. M., Ducker, G. S., Li, Y. n., Seoane, J. A., Xiao, Y. n., Melemenidis, S. n., Zhou, Y. n., Liu, L. n., Vanharanta, S. n., Graves, E. E., Rankin, E. B., Curtis, C. n., Massague, J. n., Rabinowitz, J. D., Thompson, C. B., Ye, J. n. 2020


    Breast cancer is the most common cancer among American women and a major cause of mortality. To identify metabolic pathways as potential targets to treat metastatic breast cancer, we performed metabolomics profiling on breast cancer cell line MDA-MB-231 and its tissue-tropic metastatic subclones. Here, we report that these subclones with increased metastatic potential display an altered metabolic profile compared to the parental population. In particular, the mitochondrial serine and one-carbon (1C) unit pathway is upregulated in metastatic subclones. Mechanistically, the mitochondrial serine and 1C unit pathway drives the faster proliferation of subclones through enhanced de novo purine biosynthesis. Inhibition of the first rate-limiting enzyme of the mitochondrial serine and 1C unit pathway, serine hydroxymethyltransferase (SHMT2), potently suppresses proliferation of metastatic subclones in culture and impairs growth of lung metastatic subclones at both primary and metastatic sites in mice. Some human breast cancers exhibit a significant association between the expression of genes in the mitochondrial serine and 1C unit pathway with disease outcome and higher expression of SHMT2 in metastatic tumor tissue compared to primary tumors. In addition to breast cancer, a few other cancer types, such as adrenocortical carcinoma (ACC) and kidney chromophobe cell carcinoma (KICH), also display increased SHMT2 expression during disease progression. Together, these results suggest that mitochondrial serine and 1C unit plays an important role in promoting cancer progression, particularly in late stage cancer. Implications: This study identifies mitochondrial serine and 1C unit metabolism as an important pathway during the progression of a subset of human breast cancers.

    View details for DOI 10.1158/1541-7786.MCR-19-0606

    View details for PubMedID 31941752

  • THE HYPOXIC TUMOR-MESOTHELIAL NICHE PROMOTES OVARIAN CANCER METASTASIS THROUGH COLLAGEN REMODELING Natarajan, S., Foreman, K., Soriano, M., Shehade, H., Fregoso, D., Eggold, J., Rosen, N. S., Heilshorn, S., Krieg, A. J., Krishnan, V., Dorigo, O., Sinha, S., Fuh, K. C., Rankin, E. B. AMER ASSOC CANCER RESEARCH. 2019: 168
  • S100A10 is a critical mediator of GAS6/AXL-induced angiogenesis in renal cell carcinoma. Cancer research Xiao, Y., Zhao, H., Tian, L., Nolley, R., Diep, A. N., Ernst, A., Fuh, K. C., Miao, Y. R., von Eyben, R., Leppert, J. T., Brooks, J. D., Peehl, D. M., Giaccia, A. J., Rankin, E. B. 2019


    Angiogenesis is a hallmark of cancer that promotes tumor progression and metastasis. However, antiangiogenic agents have limited efficacy in cancer therapy due to the development of resistance. In clear cell renal cell carcinoma (ccRCC), AXL expression is associated with antiangiogenic resistance and poor survival. Here, we establish a role for GAS6/AXL signaling in promoting the angiogenic potential of ccRCC cells through the regulation of the plasminogen receptor S100A10. Genetic and therapeutic inhibition of AXL signaling in ccRCC tumor xenografts reduced tumor vessel density and growth under the renal capsule. GAS6/AXL signaling activated the expression of S100A10 through SRC to promote plasmin production, endothelial cell invasion and angiogenesis. Importantly, treatment with the small molecule AXL inhibitor cabozantinib or an ultra-high affinity soluble AXL Fc fusion decoy receptor (sAXL) reduced the growth of a pazopanib-resistant ccRCC patient-derived xenograft. Moreover, the combination of sAXL synergized with pazopanib and axitinib to reduce ccRCC patient-derived xenograft growth and vessel density. These findings highlight a role for AXL/S100A10 signaling in mediating the angiogenic potential of ccRCC cells and support the combination of AXL inhibitors with antiangiogenic agents for advanced ccRCC.

    View details for DOI 10.1158/0008-5472.CAN-19-1366

    View details for PubMedID 31585940

  • Genomics and molecular mechanisms of high grade serous ovarian cancer: the 12th Biennial Rivkin Center Ovarian Cancer Research Symposium. International journal of gynecological cancer : official journal of the International Gynecological Cancer Society Rankin, E. B. 2019; 29 (Suppl 2): s7–s11


    OBJECTIVE: The aim of this study was to review current research efforts in genomics and molecular mechanisms of high grade serous ovarian cancer, presented at the 12th Biennial Rivkin Center Ovarian Cancer Research Symposium, held at the University of Washington.METHODS: The 12th Biennial Rivkin Center Ovarian Cancer Research Symposium brought together leaders in the field to discuss recent advances in ovarian cancer research and therapy.RESULTS: The genomics and molecular mechanisms of ovarian cancer session featured invited speaker presentations by Dr Alan D' Andrea on 'Deoxyribonucleic acid (DNA) repair in ovarian cancer' and Dr Kathleen Cho on 'Modeling the genomics of high grade serous carcinoma in the mouse'. Eight additional oral presentations and 46 poster presentations were selected from the submitted abstracts that highlighted current research efforts in p53, DNA repair, genomic instability and modeling disease in mice, and organoids in high grade serous ovarian cancer.CONCLUSIONS: New technologies utilizing clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR associated protein 9 (CAS9) approaches in mice, organoids, and cell based screens continue to advance our knowledge of key molecular drivers of ovarian cancer initiation, progression, and drug resistance. Improved understanding of the mechanisms of poly ADP ribose polymerase inhibitor resistance may lead to new therapeutic strategies to enhance outcomes in women with high grade serous ovarian cancer.

    View details for DOI 10.1136/ijgc-2019-000490

    View details for PubMedID 31462542

  • Modulating the tumor microenvironment to enhance efficacy of PARP inhibitors Mehibel, M., Xu, J., Diep, A., Thakkar, K., Li, C. G., Xiao, Y., Rankin, E., Giaccia, A. AMER SOC CLINICAL ONCOLOGY. 2019
  • Preclinical testing of ultra-rapid FLASH total abdominal irradiation demonstrates survival benefit and decreased gastrointestinal toxicity compared to conventional external beam radiation. Levy, K., Rafat, M., Schueler, E., Eggold, J., Wang, J., Casey, K., Koong, A., Maxim, P., Loo, B. W., Rankin, E. AMER SOC CLINICAL ONCOLOGY. 2019
  • Collagen Remodeling in the Hypoxic Tumor-Mesothelial Niche Promotes Ovarian Cancer Metastasis CANCER RESEARCH Natarajan, S., Foreman, K. M., Soriano, M., Rossen, N. S., Shehade, H., Fregoso, D. R., Eggold, J. T., Krishnan, V., Dorigo, O., Krieg, A. J., Heilshorn, S. C., Sinha, S., Fuh, K. C., Rankin, E. B. 2019; 79 (9): 2271–84
  • Collagen remodeling in the hypoxic tumor-mesothelial niche promotes ovarian cancer metastasis. Cancer research Natarajan, S., Foreman, K. M., Soriano, M. I., Rossen, N. S., Shehade, H., Fregoso, D. R., Eggold, J. T., Krishnan, V., Dorigo, O., Krieg, A. J., Heilshorn, S. C., Sinha, S., Fuh, K. C., Rankin, E. B. 2019


    Peritoneal metastases are the leading cause of morbidity and mortality in high-grade serous ovarian cancer (HGSOC). Accumulating evidence suggests that mesothelial cells are an important component of the metastatic microenvironment in HGSOC. However, the mechanisms by which mesothelial cells promote metastasis are unclear. Here we report that the HGSOC tumor-mesothelial niche was hypoxic and hypoxic signaling enhanced collagen I deposition by mesothelial cells. Specifically, hypoxic signaling increased expression of lysyl oxidase (LOX) in mesothelial and ovarian cancer cells to promote collagen crosslinking and tumor cell invasion. The mesothelial niche was enriched with fibrillar collagen in human and murine omental metastases. Pharmacologic inhibition of LOX reduced tumor burden and collagen remodeling in murine omental metastases. These findings highlight an important role for hypoxia and mesothelial cells in the modification of the extracellular matrix and tumor invasion in HGSOC.

    View details for PubMedID 30862717

  • Hypoxia-Induced Phenotypes that Mediate Tumor Heterogeneity. Advances in experimental medicine and biology Qian, J. n., Rankin, E. B. 2019; 1136: 43–55


    Intratumoral heterogeneity is an important factor contributing to metastasis and therapy resistance. The phenotypic diversity of cancer cells within the tumor microenvironment is strongly influenced by microenvironmental factors such as hypoxia. Clinically, hypoxia and the hypoxia inducible transcription factors HIF-1 and HIF-2 are associated with cancer stem cells, metastasis and drug resistance in multiple tumor types. Experimental models have demonstrated an important functional role for HIF signaling in driving CSC, metastatic and drug resistant phenotypes in vitro and in vivo. Here we will review recent studies that highlight novel mechanisms by which hypoxia promotes cancer stem cell, metastatic and drug resistant phenotypes.

    View details for DOI 10.1007/978-3-030-12734-3_3

    View details for PubMedID 31201715

  • Hypoxic signaling in the tumor-mesothelial niche promotes collagen remodeling and ovarian cancer metastasis. Foreman, K., Fuh, K., SorianoJAL, M., Dorigo, O., Krishnan, V., Shehade, H., Natarajan, S., Sinha, S., Krieg, A., Rankin, E. AMER ASSOC CANCER RESEARCH. 2018: 57
  • Erythropoiesis, EPO, macrophages, and bone. Bone Eggold, J. T., Rankin, E. B. 2018


    The regulation of erythropoiesis in the bone marrow microenvironment is a carefully orchestrated process that is dependent upon both systemic and local cues. Systemic erythropoietin (EPO) production by renal interstitial cells plays a critical role in maintaining erythropoietic homeostasis. In addition, there is increasing clinical and preclinical data linking changes in EPO and erythropoiesis to altered skeletal homeostasis, suggesting a functional relationship between the regulation of erythropoiesis and bone homeostasis. As key local components of the bone marrow microenvironment and erythropoietic niche, macrophage subsets play important roles in both processes. In this review, we summarize our current understanding of the cellular and molecular mechanisms that may facilitate the coordinated regulation of erythropoiesis and bone homeostasis.

    View details for PubMedID 29551752

  • Systematic discovery of mutation-specific synthetic lethals by mining pan-cancer human primary tumor data. Nature communications Sinha, S., Thomas, D., Chan, S., Gao, Y., Brunen, D., Torabi, D., Reinisch, A., Hernandez, D., Chan, A., Rankin, E. B., Bernards, R., Majeti, R., Dill, D. L. 2017; 8: 15580-?


    Two genes are synthetically lethal (SL) when defects in both are lethal to a cell but a single defect is non-lethal. SL partners of cancer mutations are of great interest as pharmacological targets; however, identifying them by cell line-based methods is challenging. Here we develop MiSL (Mining Synthetic Lethals), an algorithm that mines pan-cancer human primary tumour data to identify mutation-specific SL partners for specific cancers. We apply MiSL to 12 different cancers and predict 145,891 SL partners for 3,120 mutations, including known mutation-specific SL partners. Comparisons with functional screens show that MiSL predictions are enriched for SLs in multiple cancers. We extensively validate a SL interaction identified by MiSL between the IDH1 mutation and ACACA in leukaemia using gene targeting and patient-derived xenografts. Furthermore, we apply MiSL to pinpoint genetic biomarkers for drug sensitivity. These results demonstrate that MiSL can accelerate precision oncology by identifying mutation-specific targets and biomarkers.

    View details for DOI 10.1038/ncomms15580

    View details for PubMedID 28561042

  • Inhibition of the GAS6/AXL pathway augments the efficacy of chemotherapies JOURNAL OF CLINICAL INVESTIGATION Kariolis, M. S., Miao, Y. R., Diep, A., Nash, S. E., Olcina, M. M., Jiang, D., Jones, D. S., Kapur, S., Mathews, I. I., Koong, A. C., Rankin, E. B., Cochran, J. R., Giaccia, A. J. 2017; 127 (1): 183-198


    The AXL receptor and its activating ligand, growth arrest-specific 6 (GAS6), are important drivers of metastasis and therapeutic resistance in human cancers. Given the critical roles that GAS6 and AXL play in refractory disease, this signaling axis represents an attractive target for therapeutic intervention. However, the strong picomolar binding affinity between GAS6 and AXL and the promiscuity of small molecule inhibitors represent important challenges faced by current anti-AXL therapeutics. Here, we have addressed these obstacles by engineering a second-generation, high-affinity AXL decoy receptor with an apparent affinity of 93 femtomolar to GAS6. Our decoy receptor, MYD1-72, profoundly inhibited disease progression in aggressive preclinical models of human cancers and induced cell killing in leukemia cells. When directly compared with the most advanced anti-AXL small molecules in the clinic, MYD1-72 achieved superior antitumor efficacy while displaying no toxicity. Moreover, we uncovered a relationship between AXL and the cellular response to DNA damage whereby abrogation of AXL signaling leads to accumulation of the DNA-damage markers γH2AX, 53BP1, and RAD51. MYD1-72 exploited this relationship, leading to improvements upon the therapeutic index of current standard-of-care chemotherapies in preclinical models of advanced pancreatic and ovarian cancer.

    View details for DOI 10.1172/JCI85610

    View details for Web of Science ID 000392271300021

    View details for PubMedID 27893463

    View details for PubMedCentralID PMC5199716

  • Targeting integrins with RGD-conjugated gold nanoparticles in radiotherapy decreases the invasive activity of breast cancer cells. International journal of nanomedicine Wu, P. H., Onodera, Y. n., Ichikawa, Y. n., Rankin, E. B., Giaccia, A. J., Watanabe, Y. n., Qian, W. n., Hashimoto, T. n., Shirato, H. n., Nam, J. M. 2017; 12: 5069–85


    Gold nanoparticles (AuNPs) have recently attracted attention as clinical agents for enhancing the effect of radiotherapy in various cancers. Although radiotherapy is a standard treatment for cancers, invasive recurrence and metastasis are significant clinical problems. Several studies have suggested that radiation promotes the invasion of cancer cells by activating molecular mechanisms involving integrin and fibronectin (FN). In this study, polyethylene-glycolylated AuNPs (P-AuNPs) were conjugated with Arg-Gly-Asp (RGD) peptides (RGD/P-AuNPs) to target cancer cells expressing RGD-binding integrins such as α5- and αv-integrins. RGD/P-AuNPs were internalized more efficiently and colocalized with integrins in the late endosomes and lysosomes of MDA-MB-231 cells. A combination of RGD/P-AuNPs and radiation reduced cancer cell viability and increased DNA damage compared to radiation alone in MDA-MB-231 cells. Moreover, the invasive activity of breast cancer cell lines after radiation treatment was significantly inhibited in the presence of RGD/P-AuNPs. Microarray analyses revealed that the expression of FN in irradiated cells was suppressed by combined use of RGD/P-AuNPs. Reduction of FN and downstream signaling may be involved in suppressing radiation-induced invasive activity by RGD/P-AuNPs. Our study suggests that RGD/P-AuNPs can target integrin-overexpressing cancer cells to improve radiation therapy by suppressing invasive activity in addition to sensitization. Thus, these findings provide a possible clinical strategy for using AuNPs to treat invasive breast cancer following radiotherapy.

    View details for PubMedID 28860745

    View details for PubMedCentralID PMC5560413

  • Cabozantinib inhibits tumor growth and metastasis of a patient-derived xenograft model of papillary renal cell carcinoma with MET mutation CANCER BIOLOGY & THERAPY Zhao, H., Nolley, R., Chan, A. W., Rankin, E. B., Peehl, D. M. 2017; 18 (11): 863–71
  • Reprogramming the immunological microenvironment through radiation and targeting Axl NATURE COMMUNICATIONS Aguilera, T. A., Rafat, M., Castellini, L., Shehade, H., Kariolis, M. S., Hui, A. B., Stehr, H., von Eyben, R., Jiang, D., Ellies, L. G., Koong, A. C., Diehn, M., Rankin, E. B., Graves, E. E., Giaccia, A. J. 2016; 7


    Increasing evidence suggests that ionizing radiation therapy (RT) in combination with checkpoint immunotherapy is highly effective in treating a subset of cancers. To better understand the limited responses to this combination we analysed the genetic, microenvironmental, and immune factors in tumours derived from a transgenic breast cancer model. We identified two tumours with similar growth characteristics but different RT responses primarily due to an antitumour immune response. The combination of RT and checkpoint immunotherapy resulted in cures in the responsive but not the unresponsive tumours. Profiling the tumours revealed that the Axl receptor tyrosine kinase is overexpressed in the unresponsive tumours, and Axl knockout resulted in slower growth and increased radiosensitivity. These changes were associated with a CD8(+) T-cell response, which was improved in combination with checkpoint immunotherapy. These results suggest a novel role for Axl in suppressing antigen presentation through MHCI, and enhancing cytokine release, which promotes a suppressive myeloid microenvironment.

    View details for DOI 10.1038/ncomms13898

    View details for Web of Science ID 000390399500001

    View details for PubMedID 28008921

    View details for PubMedCentralID PMC5196438

  • The Receptor Tyrosine Kinase AXL in Cancer Progression. Cancers Rankin, E. B., Giaccia, A. J. 2016; 8 (11)


    The AXL receptor tyrosine kinase (AXL) has emerged as a promising therapeutic target for cancer therapy. Recent studies have revealed a central role of AXL signaling in tumor proliferation, survival, stem cell phenotype, metastasis, and resistance to cancer therapy. Moreover, AXL is expressed within cellular components of the tumor microenvironment where AXL signaling contributes to the immunosuppressive and protumorigenic phenotypes. A variety of AXL inhibitors have been developed and are efficacious in preclinical studies. These agents offer new opportunities for therapeutic intervention in the prevention and treatment of advanced disease. Here we review the literature that has illuminated the cellular and molecular mechanisms by which AXL signaling promotes tumor progression and we will discuss the therapeutic potential of AXL inhibition for cancer therapy.

    View details for PubMedID 27834845

  • AXL modulates extracellular matrix protein expression and is essential for invasion and metastasis in endometrial cancer. Oncotarget Divine, L. M., Nguyen, M. R., Meller, E., Desai, R. A., Arif, B., Rankin, E. B., Bligard, K. H., Meyerson, C., Hagemann, I. S., Massad, M., Thaker, P. H., Hagemann, A. R., McCourt, C. K., Powell, M. A., Mutch, D. G., Fuh, K. C. 2016


    The receptor tyrosine kinase AXL promotes migration, invasion, and metastasis. Here, we evaluated the role of AXL in endometrial cancer. High immunohistochemical expression of AXL was found in 76% (63/83) of advanced-stage, and 77% (82/107) of high-grade specimens and correlated with worse survival in uterine serous cancer patients. In vitro, genetic silencing of AXL inhibited migration and invasion but had no effect on proliferation of ARK1 endometrial cancer cells. AXL-deficient cells showed significantly decreased expression of phospho-AKT as well as uPA, MMP-1, MMP-2, MMP-3, and MMP-9. In a xenograft model of human uterine serous carcinoma with AXL-deficient ARK1 cells, there was significantly less tumor burden than xenografts with control ARK1 cells. Together, these findings underscore the therapeutic potentials of AXL as a candidate target for treatment of metastatic endometrial cancer.

    View details for DOI 10.18632/oncotarget.12637

    View details for PubMedID 27764792

  • Cabozantinib inhibits tumor growth and metastasis of a patient-derived xenograft model of papillary renal cell carcinoma with MET mutation. Cancer biology & therapy Zhao, H., Nolley, R., Chan, A. M., Rankin, E. B., Peehl, D. M. 2016: 0-?


    MET plays an important role in the development and progression of papillary renal cell carcinoma (pRCC). Evaluation of efficacy of MET inhibitors against pRCC has been hampered by limited preclinical models depicting MET abnormalities. We established a new patient-derived xenograft (PDX) model of pRCC carrying an activating mutation of MET and tested the ability of cabozantinib, an inhibitor of receptor tyrosine kinases including MET, to inhibit tumor growth and metastasis. Precision-cut, thin tissue slices from a pRCC specimen obtained by nephrectomy were implanted under the renal capsule of RAG2(-/-)γC(-/-) mice to establish first generation TSG-RCC-030. Histologic and genetic fidelity and metastatic potential of this model were characterized by immunohistochemistry, direct DNA sequencing and quantitative polymerase chain reaction (qPCR). The effect of cabozantinib on tumor growth and metastasis was evaluated. Whether measurements of circulating tumor DNA (ctDNA) by allele-specific qPCR could be used as a biomarker of tumor growth and response to therapy was determined. Subrenal and subcutaneous tumor grafts showed high take rates and metastasized to the lung. Both primary tumors and metastases expressed typical markers of pRCC and carried the same activating MET mutation as the parental tumor. Cabozantinib treatment caused striking tumor regression and inhibited lung metastasis in TSG-RCC-030. Plasma ctDNA levels correlated with tumor volume in control mice and changed in response to cabozantinib treatment. TSG-RCC-030 provides a realistic preclinical model to better understand the development and progression of pRCC with MET mutation and accelerate the development of new therapies for pRCC.

    View details for PubMedID 27715452

  • Polycomb repressive complex 2 regulates skeletal growth by suppressing Wnt and TGF-beta signalling NATURE COMMUNICATIONS Mirzamohammadi, F., Papaioannou, G., Inloes, J. B., Rankin, E. B., Xie, H., Schipani, E., Orkin, S. H., Kobayashi, T. 2016; 7


    Polycomb repressive complex 2 (PRC2) controls maintenance and lineage determination of stem cells by suppressing genes that regulate cellular differentiation and tissue development. However, the role of PRC2 in lineage-committed somatic cells is mostly unknown. Here we show that Eed deficiency in chondrocytes causes severe kyphosis and a growth defect with decreased chondrocyte proliferation, accelerated hypertrophic differentiation and cell death with reduced Hif1a expression. Eed deficiency also causes induction of multiple signalling pathways in chondrocytes. Wnt signalling overactivation is responsible for the accelerated hypertrophic differentiation and kyphosis, whereas the overactivation of TGF-β signalling is responsible for the reduced proliferation and growth defect. Thus, our study demonstrates that PRC2 has an important regulatory role in lineage-committed tissue cells by suppressing overactivation of multiple signalling pathways.

    View details for DOI 10.1038/ncomms12047

    View details for Web of Science ID 000379092100001

    View details for PubMedID 27329220

    View details for PubMedCentralID PMC4917962

  • Hypoxia: Signaling the Metastatic Cascade. Trends in cancer Rankin, E. B., Nam, J. M., Giaccia, A. J. 2016; 2 (6): 295-304


    Hypoxia is a potent microenvironmental factor that promotes tumor metastasis. Recent studies have revealed mechanisms by which hypoxia and activation of hypoxia inducible factor (HIF)-dependent signaling promotes metastasis through the regulation of metabolic reprogramming, the stem cell phenotype, invasion, angiogenesis, immune suppression, the premetastatic niche, intravasation and/or extravasation, and resistance to apoptosis. These discoveries suggest novel paradigms in tumor metastasis and identify new opportunities for therapeutic intervention in the prevention and treatment of metastatic disease. Here, we review the impact of hypoxia and hypoxic signaling pathways in tumor and stromal cells on each step of the metastatic cascade.

    View details for DOI 10.1016/j.trecan.2016.05.006

    View details for PubMedID 28741527

    View details for PubMedCentralID PMC5808868

  • Targeting MET and AXL overcomes resistance to sunitinib therapy in renal cell carcinoma ONCOGENE Zhou, L., Liu, X., Sun, M., Zhang, X., German, P., Bai, S., Ding, Z., Tannir, N., Wood, C. G., Matin, S. F., Karam, J. A., Tamboli, P., Sircar, K., Rao, P., Rankin, E. B., Laird, D. A., Hoang, A. G., Walker, C. L., Giaccia, A. J., Jonasch, E. 2016; 35 (21): 2687-2697


    Antiangiogenic therapy resistance occurs frequently in patients with metastatic renal cell carcinoma (RCC). The purpose of this study was to understand the mechanism of resistance to sunitinib, an antiangiogenic small molecule, and to exploit this mechanism therapeutically. We hypothesized that sunitinib-induced upregulation of the prometastatic MET and AXL receptors is associated with resistance to sunitinib and with more aggressive tumor behavior. In the present study, tissue microarrays containing sunitinib-treated and untreated RCC tissues were stained with MET and AXL antibodies. The low malignant RCC cell line 786-O was chronically treated with sunitinib and assayed for AXL, MET, epithelial-mesenchymal transition (EMT) protein expression and activation. Co-culture experiments were used to examine the effect of sunitinib pretreatment on endothelial cell growth. The effects of AXL and MET were evaluated in various cell-based models by short hairpin RNA or inhibition by cabozantinib, the multi-tyrosine kinases inhibitor that targets vascular endothelial growth factor receptor, MET and AXL. Xenograft mouse models tested the ability of cabozantinib to rescue sunitinib resistance. We demonstrated that increased AXL and MET expression was associated with inferior clinical outcome in patients. Chronic sunitinib treatment of RCC cell lines activated both AXL and MET, induced EMT-associated gene expression changes, including upregulation of Snail and β-catenin, and increased cell migration and invasion. Pretreatment with sunitinib enhanced angiogenesis in 786-0/human umbilical vein endothelial cell co-culture models. The suppression of AXL or MET expression and the inhibition of AXL and MET activation using cabozantinib both impaired chronic sunitinib treatment-induced prometastatic behavior in cell culture and rescued acquired resistance to sunitinib in xenograft models. In summary, chronic sunitinib treatment induces the activation of AXL and MET signaling and promotes prometastatic behavior and angiogenesis. The inhibition of AXL and MET activity may overcome resistance induced by prolonged sunitinib therapy in metastatic RCC.

    View details for DOI 10.1038/onc.2015.343

    View details for Web of Science ID 000377472700003

    View details for PubMedID 26364599

    View details for PubMedCentralID PMC4791213

  • Hypoxic control of metastasis SCIENCE Rankin, E. B., Giaccia, A. J. 2016; 352 (6282): 175-180


    Metastatic disease is the leading cause of cancer-related deaths and involves critical interactions between tumor cells and the microenvironment. Hypoxia is a potent microenvironmental factor promoting metastatic progression. Clinically, hypoxia and the expression of the hypoxia-inducible transcription factors HIF-1 and HIF-2 are associated with increased distant metastasis and poor survival in a variety of tumor types. Moreover, HIF signaling in malignant cells influences multiple steps within the metastatic cascade. Here we review research focused on elucidating the mechanisms by which the hypoxic tumor microenvironment promotes metastatic progression. These studies have identified potential biomarkers and therapeutic targets regulated by hypoxia that could be incorporated into strategies aimed at preventing and treating metastatic disease.

    View details for DOI 10.1126/science.aaf4405

    View details for Web of Science ID 000373681600036

    View details for PubMedID 27124451

    View details for PubMedCentralID PMC4898055

  • Biology of the bone marrow microenvironment and myelodysplastic syndromes. Molecular genetics and metabolism Rankin, E. B., Narla, A., Park, J. K., Lin, S., Sakamoto, K. M. 2015; 116 (1-2): 24-28


    Myelodysplastic syndromes (MDS) are characterized by cytopenias resulting from ineffective hematopoiesis with a predisposition to transform to acute myeloid leukemia (AML). Recent evidence suggests that the hematopoietic stem cell microenvironment contributes to the pathogenesis of MDS. Inflammation and hypoxia within the bone marrow are key regulators of hematopoietic stem and progenitor cells that can lead to several bone marrow failure syndromes, including MDS. In this brief review, we provide an overview of the clinical and molecular features of MDS, the bone marrow microenvironment, and specific pathways that lead to abnormal blood cell development in MDS. Characterization of key steps in the pathogenesis of MDS will lead to new approaches to treat patients with this disease.

    View details for DOI 10.1016/j.ymgme.2015.07.004

    View details for PubMedID 26210353

    View details for PubMedCentralID PMC4618471

  • Oxygen-sensing PHDs regulate bone homeostasis through the modulation of osteoprotegerin GENES & DEVELOPMENT Wu, C., Rankin, E. B., Castellini, L., Fernandez-Alcudia, J., Lagory, E. L., Andersen, R., Rhodes, S. D., Wilson, T. L., Mohammad, K. S., Castillo, A. B., Guise, T. A., Schipani, E., Giaccia, A. J. 2015; 29 (8): 817-831


    The bone microenvironment is composed of niches that house cells across variable oxygen tensions. However, the contribution of oxygen gradients in regulating bone and blood homeostasis remains unknown. Here, we generated mice with either single or combined genetic inactivation of the critical oxygen-sensing prolyl hydroxylase (PHD) enzymes (PHD1-3) in osteoprogenitors. Hypoxia-inducible factor (HIF) activation associated with Phd2 and Phd3 inactivation drove bone accumulation by modulating osteoblastic/osteoclastic cross-talk through the direct regulation of osteoprotegerin (OPG). In contrast, combined inactivation of Phd1, Phd2, and Phd3 resulted in extreme HIF signaling, leading to polycythemia and excessive bone accumulation by overstimulating angiogenic-osteogenic coupling. We also demonstrate that genetic ablation of Phd2 and Phd3 was sufficient to protect ovariectomized mice against bone loss without disrupting hematopoietic homeostasis. Importantly, we identify OPG as a HIF target gene capable of directing osteoblast-mediated osteoclastogenesis to regulate bone homeostasis. Here, we show that coordinated activation of specific PHD isoforms fine-tunes the osteoblastic response to hypoxia, thereby directing two important aspects of bone physiology: cross-talk between osteoblasts and osteoclasts and angiogenic-osteogenic coupling.

    View details for DOI 10.1101/gad.255000.114

    View details for Web of Science ID 000353027600004

    View details for PubMedID 25846796

    View details for PubMedCentralID PMC4403258

  • Hypoxic induction of AKAP12 variant 2 shifts PKA-mediated protein phosphorylation to enhance migration and metastasis of melanoma cells PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Finger, E. C., Castellini, L., Rankin, E. B., Vilalta, M., Krieg, A. J., Jiang, D., Banh, A., Zundel, W., Powell, M. B., Giaccia, A. J. 2015; 112 (14): 4441-4446


    Scaffold proteins are critical hubs within cells that have the ability to modulate upstream signaling molecules and their downstream effectors to fine-tune biological responses. Although they can serve as focal points for association of signaling molecules and downstream pathways that regulate tumorigenesis, little is known about how the tumor microenvironment affects the expression and activity of scaffold proteins. This study demonstrates that hypoxia, a common element of solid tumors harboring low oxygen levels, regulates expression of a specific variant of the scaffold protein AKAP12 (A-kinase anchor protein 12), AKAP12v2, in metastatic melanoma. In turn, through a kinome-wide phosphoproteomic and MS study, we demonstrate that this scaffolding protein regulates a shift in protein kinase A (PKA)-mediated phosphorylation events under hypoxia, causing alterations in tumor cell invasion and migration in vitro, as well as metastasis in an in vivo orthotopic model of melanoma. Mechanistically, the shift in AKAP12-dependent PKA-mediated phosphorylations under hypoxia is due to changes in AKAP12 localization vs. structural differences between its two variants. Importantly, our work defines a mechanism through which a scaffold protein can be regulated by the tumor microenvironment and further explains how a tumor cell can coordinate many critical signaling pathways that are essential for tumor growth through one individual scaffolding protein.

    View details for DOI 10.1073/pnas.1418164112

    View details for PubMedID 25792458

  • Osteoblasts: a novel source of erythropoietin. Current osteoporosis reports Wu, C., Giaccia, A. J., Rankin, E. B. 2014; 12 (4): 428-432


    Osteoblasts are an important cellular component of the bone microenvironment controlling bone formation and hematopoiesis. Understanding the cellular and molecular mechanisms by which osteoblasts regulate these processes is a rapidly growing area of research given the important implications for bone therapy, regenerative medicine, and hematopoietic stem cell transplantation. Here we summarize our current knowledge regarding the cellular and molecular crosstalk driving bone formation and hematopoiesis and will discuss the implications of a recent finding demonstrating that osteoblasts are a cellular source of erythropoietin .

    View details for DOI 10.1007/s11914-014-0236-x

    View details for PubMedID 25204993

  • Osteoblasts: a novel source of erythropoietin. Current osteoporosis reports Wu, C., Giaccia, A. J., Rankin, E. B. 2014; 12 (4): 428-432

    View details for DOI 10.1007/s11914-014-0236-x

    View details for PubMedID 25204993

  • Direct regulation of GAS6/AXL signaling by HIF promotes renal metastasis through SRC and MET PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Rankin, E. B., Fuh, K. C., Castellini, L., Viswanathan, K., Finger, E. C., Diep, A. N., Lagory, E. L., Kariolis, M. S., Chan, A., Lindgren, D., Axelson, H., Miao, Y. R., Krieg, A. J., Giaccia, A. J. 2014; 111 (37): 13373-13378
  • Direct regulation of GAS6/AXL signaling by HIF promotes renal metastasis through SRC and MET. Proceedings of the National Academy of Sciences of the United States of America Rankin, E. B., Fuh, K. C., Castellini, L., Viswanathan, K., Finger, E. C., Diep, A. N., Lagory, E. L., Kariolis, M. S., Chan, A., Lindgren, D., Axelson, H., MIAO, Y. R., Krieg, A. J., Giaccia, A. J. 2014; 111 (37): 13373-13378


    Dysregulation of the von Hippel-Lindau/hypoxia-inducible transcription factor (HIF) signaling pathway promotes clear cell renal cell carcinoma (ccRCC) progression and metastasis. The protein kinase GAS6/AXL signaling pathway has recently been implicated as an essential mediator of metastasis and receptor tyrosine kinase crosstalk in cancer. Here we establish a molecular link between HIF stabilization and induction of AXL receptor expression in metastatic ccRCC. We found that HIF-1 and HIF-2 directly activate the expression of AXL by binding to the hypoxia-response element in the AXL proximal promoter. Importantly, genetic and therapeutic inactivation of AXL signaling in metastatic ccRCC cells reversed the invasive and metastatic phenotype in vivo. Furthermore, we define a pathway by which GAS6/AXL signaling uses lateral activation of the met proto-oncogene (MET) through SRC proto-oncogene nonreceptor tyrosine kinase to maximize cellular invasion. Clinically, AXL expression in primary tumors of ccRCC patients correlates with aggressive tumor behavior and patient lethality. These findings provide an alternative model for SRC and MET activation by growth arrest-specific 6 in ccRCC and identify AXL as a therapeutic target driving the aggressive phenotype in renal clear cell carcinoma.

    View details for DOI 10.1073/pnas.1404848111

    View details for PubMedID 25187556

  • Loss of VHL in mesenchymal progenitors of the limb bud alters multiple steps of endochondral bone development. Developmental biology Mangiavini, L., Merceron, C., Araldi, E., Khatri, R., Gerard-O'Riley, R., LeShan Wilson, T., Rankin, E. B., Giaccia, A. J., Schipani, E. 2014; 393 (1): 124-136


    Adaptation to low oxygen tension (hypoxia) is a critical event during development. The transcription factors Hypoxia Inducible Factor-1α (HIF-1α) and HIF-2α are essential mediators of the homeostatic responses that allow hypoxic cells to survive and differentiate. Von Hippel-Lindau protein (VHL) is the E3 ubiquitin ligase that targets HIFs to the proteasome for degradation in normoxia. We have previously demonstrated that the transcription factor HIF-1α is essential for survival and differentiation of growth plate chondrocytes, whereas HIF-2α is not necessary for fetal growth plate development. We have also shown that VHL is important for endochondral bone development, since loss of VHL in chondrocytes causes severe dwarfism. In this study, in order to expand our understanding of the role of VHL in chondrogenesis, we conditionally deleted VHL in mesenchymal progenitors of the limb bud, i.e. in cells not yet committed to the chondrocyte lineage. Deficiency of VHL in limb bud mesenchyme does not alter the timely differentiation of mesenchymal cells into chondrocytes. However, it causes structural collapse of the cartilaginous growth plate as a result of impaired proliferation, delayed terminal differentiation, and ectopic death of chondrocytes. This phenotype is associated to delayed replacement of cartilage by bone. Notably, loss of HIF-2α fully rescues the late formation of the bone marrow cavity in VHL mutant mice, though it does not affect any other detectable abnormality of the VHL mutant growth plates. Our findings demonstrate that VHL regulates bone morphogenesis as its loss considerably alters size, shape and overall development of the skeletal elements.

    View details for DOI 10.1016/j.ydbio.2014.06.013

    View details for PubMedID 24972088

  • PHD inhibition mitigates and protects against radiation-induced gastrointestinal toxicity via HIF2. Science translational medicine Taniguchi, C. M., Miao, Y. R., Diep, A. N., Wu, C., Rankin, E. B., Atwood, T. F., Xing, L., Giaccia, A. J. 2014; 6 (236): 236ra64-?


    Radiation-induced gastrointestinal (GI) toxicity can be a major source of morbidity and mortality after radiation exposure. There is an unmet need for effective preventative or mitigative treatments against the potentially fatal diarrhea and water loss induced by radiation damage to the GI tract. We report that prolyl hydroxylase inhibition by genetic knockout or pharmacologic inhibition of all PHD (prolyl hydroxylase domain) isoforms by the small-molecule dimethyloxallyl glycine (DMOG) increases hypoxia-inducible factor (HIF) expression, improves epithelial integrity, reduces apoptosis, and increases intestinal angiogenesis, all of which are essential for radioprotection. HIF2, but not HIF1, is both necessary and sufficient to prevent radiation-induced GI toxicity and death. Increased vascular endothelial growth factor (VEGF) expression contributes to the protective effects of HIF2, because inhibition of VEGF function reversed the radioprotection and radiomitigation afforded by DMOG. Additionally, mortality from abdominal or total body irradiation was reduced even when DMOG was given 24 hours after exposure. Thus, prolyl hydroxylase inhibition represents a treatment strategy to protect against and mitigate GI toxicity from both therapeutic radiation and potentially lethal radiation exposures.

    View details for DOI 10.1126/scitranslmed.3008523

    View details for PubMedID 24828078

    View details for PubMedCentralID PMC4136475

  • PHD Inhibition Mitigates and Protects Against Radiation-Induced Gastrointestinal Toxicity via HIF2. Science translational medicine Taniguchi, C. M., Miao, Y. R., Diep, A. N., Wu, C., Rankin, E. B., Atwood, T. F., Xing, L., Giaccia, A. J. 2014; 6 (236): 236ra64-?


    Radiation-induced gastrointestinal (GI) toxicity can be a major source of morbidity and mortality after radiation exposure. There is an unmet need for effective preventative or mitigative treatments against the potentially fatal diarrhea and water loss induced by radiation damage to the GI tract. We report that prolyl hydroxylase inhibition by genetic knockout or pharmacologic inhibition of all PHD (prolyl hydroxylase domain) isoforms by the small-molecule dimethyloxallyl glycine (DMOG) increases hypoxia-inducible factor (HIF) expression, improves epithelial integrity, reduces apoptosis, and increases intestinal angiogenesis, all of which are essential for radioprotection. HIF2, but not HIF1, is both necessary and sufficient to prevent radiation-induced GI toxicity and death. Increased vascular endothelial growth factor (VEGF) expression contributes to the protective effects of HIF2, because inhibition of VEGF function reversed the radioprotection and radiomitigation afforded by DMOG. Additionally, mortality from abdominal or total body irradiation was reduced even when DMOG was given 24 hours after exposure. Thus, prolyl hydroxylase inhibition represents a treatment strategy to protect against and mitigate GI toxicity from both therapeutic radiation and potentially lethal radiation exposures.

    View details for DOI 10.1126/scitranslmed.3008523

    View details for PubMedID 24828078

    View details for PubMedCentralID PMC4136475

  • CTGF is a therapeutic target for metastatic melanoma. Oncogene Finger, E. C., Cheng, C., Williams, T. R., Rankin, E. B., Bedogni, B., Tachiki, L., Spong, S., Giaccia, A. J., Powell, M. B. 2014; 33 (9): 1093-1100


    Metastatic melanoma remains a devastating disease with a 5-year survival rate of less than five percent. Despite recent advances in targeted therapies for melanoma, only a small percentage of melanoma patients experience durable remissions. Therefore, it is critical to identify new therapies for the treatment of advanced melanoma. Here, we define connective tissue growth factor (CTGF) as a therapeutic target for metastatic melanoma. Clinically, CTGF expression correlates with tumor progression and is strongly induced by hypoxia through HIF-1 and HIF-2-dependent mechanisms. Genetic inhibition of CTGF in human melanoma cells is sufficient to significantly reduce orthotopic tumor growth, as well as metastatic tumor growth in the lung of severe combined immunodeficient (SCID) mice. Mechanistically, inhibition of CTGF decreased invasion and migration associated with reduced matrix metalloproteinase-9 expression. Most importantly, the anti-CTGF antibody, FG-3019, had a profound inhibitory effect on the progression of established metastatic melanoma. These results offer the first preclinical validation of anti-CTGF therapy for the treatment of advanced melanoma and underscore the importance of tumor hypoxia in melanoma progression.Oncogene advance online publication, 25 February 2013; doi:10.1038/onc.2013.47.

    View details for DOI 10.1038/onc.2013.47

    View details for PubMedID 23435419

  • Regulation of Bone Marrow Angiogenesis by Osteoblasts during Bone Development and Homeostasis. Frontiers in endocrinology Schipani, E., Wu, C., Rankin, E. B., Giaccia, A. J. 2013; 4: 85-?


    Bone marrow is a highly heterogeneous and vascularized tissue. The various cell types populating the bone marrow extensively communicate with each other, and cell-to-cell cross talk is likely to be essential for proper bone development and homeostasis. In particular, the existence of osteogenesis and angiogenesis coupling has been recently proposed. Despite its high degree of vascularization, a gradient of oxygenation is present in the bone marrow, and the endosteal surface of cortical bone appears to be among the most hypoxic areas in the body. Oxygen (O2) is both an essential metabolic substrate and a regulatory signal that is in charge of a specific genetic program. An important component of this program is the family of transcription factors known as hypoxia-inducible factors (HIFs). In this Perspective, we will summarize our current knowledge about the role of the HIF signaling pathway in controlling bone development and homeostasis, and especially in regulating the crosstalk between osteoblasts, progenitor cells, and bone marrow blood vessels.

    View details for DOI 10.3389/fendo.2013.00085

    View details for PubMedID 23847596

  • Blood and bones Osteoblastic HIF signaling regulates erythropoiesis CELL CYCLE Wu, C., Rankin, E. B., Giaccia, A. J. 2012; 11 (12): 2221-2222

    View details for DOI 10.4161/cc.20635

    View details for Web of Science ID 000305353000003

    View details for PubMedID 22627672

    View details for PubMedCentralID PMC3383578

  • The HIF Signaling Pathway in Osteoblasts Directly Modulates Erythropoiesis through the Production of EPO CELL Rankin, E. B., Wu, C., Khatri, R., Wilson, T. L., Andersen, R., Araldi, E., Rankin, A. L., Yuan, J., Kuo, C. J., Schipani, E., Giaccia, A. J. 2012; 149 (1): 63-74


    Osteoblasts are an important component of the hematopoietic microenvironment in bone. However, the mechanisms by which osteoblasts control hematopoiesis remain unknown. We show that augmented HIF signaling in osteoprogenitors results in HSC niche expansion associated with selective expansion of the erythroid lineage. Increased red blood cell production occurred in an EPO-dependent manner with increased EPO expression in bone and suppressed EPO expression in the kidney. In contrast, inactivation of HIF in osteoprogenitors reduced EPO expression in bone. Importantly, augmented HIF activity in osteoprogenitors protected mice from stress-induced anemia. Pharmacologic or genetic inhibition of prolyl hydroxylases1/2/3 in osteoprogenitors elevated EPO expression in bone and increased hematocrit. These data reveal an unexpected role for osteoblasts in the production of EPO and modulation of erythropoiesis. Furthermore, these studies demonstrate a molecular role for osteoblastic PHD/VHL/HIF signaling that can be targeted to elevate both HSCs and erythroid progenitors in the local hematopoietic microenvironment.

    View details for DOI 10.1016/j.cell.2012.01.051

    View details for Web of Science ID 000302235400010

    View details for PubMedID 22464323

    View details for PubMedCentralID PMC3408231

  • A central role for hypoxic signaling in cartilage, bone, and hematopoiesis. Current osteoporosis reports Rankin, E. B., Giaccia, A. J., Schipani, E. 2011; 9 (2): 46-52


    Hypoxic signaling plays an essential role in maintaining oxygen homeostasis and cell survival. Hypoxia-inducible transcription factors HIF-1 and HIF-2 are central mediators of the cellular response to hypoxia by regulating the expression of genes controlling metabolic adaptation, oxygen delivery, and survival in response to oxygen deprivation. Recent studies have identified an important role for HIF-1 and HIF-2 in the regulation of skeletal development, bone formation, and regeneration, as well as joint formation and homeostasis. In addition, overexpression of HIF-1 and HIF-2 is clinically associated with osteosarcoma and osteoarthritis. Together, these findings implicate hypoxic signaling as a central regulator of bone biology and disease.

    View details for DOI 10.1007/s11914-011-0047-2

    View details for PubMedID 21360287

  • AXL Is an Essential Factor and Therapeutic Target for Metastatic Ovarian Cancer CANCER RESEARCH Rankin, E. B., Fuh, K. C., Taylor, T. E., Krieg, A. J., Musser, M., Yuan, J., Wei, K., Kuo, C. J., Longacre, T. A., Giaccia, A. J. 2010; 70 (19): 7570-7579


    The receptor tyrosine kinase AXL is thought to play a role in metastasis; however, the therapeutic efficacy of an AXL-targeting agent remains largely untested in metastatic disease. In this study, we defined AXL as a therapeutic target for metastatic ovarian cancer. AXL is primarily expressed in metastases and advanced-stage human ovarian tumors but not in normal ovarian epithelium. Genetic inhibition of AXL in human metastatic ovarian tumor cells is sufficient to prevent the initiation of metastatic disease in vivo. Mechanistically, inhibition of AXL signaling in animals with metastatic disease results in decreased invasion and matrix metalloproteinase activity. Most importantly, soluble human AXL receptors that imposed a specific blockade of the GAS6/AXL pathway had a profound inhibitory effect on progression of established metastatic ovarian cancer without normal tissue toxicity. These results offer the first genetic validation of GAS6/AXL targeting as an effective strategy for inhibition of metastatic tumor progression in vivo. Furthermore, this study defines the soluble AXL receptor as a therapeutic candidate agent for treatment of metastatic ovarian cancer, for which current therapies are ineffective.

    View details for DOI 10.1158/0008-5472.CAN-10-1267

    View details for Web of Science ID 000282647700021

    View details for PubMedID 20858715

    View details for PubMedCentralID PMC3408227

  • Regulation of the Histone Demethylase JMJD1A by Hypoxia-Inducible Factor 1 alpha Enhances Hypoxic Gene Expression and Tumor Growth MOLECULAR AND CELLULAR BIOLOGY Krieg, A. J., Rankin, E. B., Chan, D., Razorenova, O., Fernandez, S., Giaccia, A. J. 2010; 30 (1): 344-353


    The hypoxia-inducible transcription factors (HIFs) directly and indirectly mediate cellular adaptation to reduced oxygen tensions. Recent studies have shown that the histone demethylase genes JMJD1A, JMJD2B, and JARID1B are HIF targets, suggesting that HIFs indirectly influence gene expression at the level of histone methylation under hypoxia. In this study, we identify a subset of hypoxia-inducible genes that are dependent on JMJD1A in both renal cell and colon carcinoma cell lines. JMJD1A regulates the expression of adrenomedullin (ADM) and growth and differentiation factor 15 (GDF15) under hypoxia by decreasing promoter histone methylation. In addition, we demonstrate that loss of JMJD1A is sufficient to reduce tumor growth in vivo, demonstrating that histone demethylation plays a significant role in modulating growth within the tumor microenvironment. Thus, hypoxic regulation of JMJD1A acts as a signal amplifier to facilitate hypoxic gene expression, ultimately enhancing tumor growth.

    View details for DOI 10.1128/MCB.00444-09

    View details for Web of Science ID 000272569200028

    View details for PubMedID 19858293

    View details for PubMedCentralID PMC2798291

  • Hypoxia-Inducible Factor 2 Regulates Hepatic Lipid Metabolism MOLECULAR AND CELLULAR BIOLOGY Rankin, E. B., Rha, J., Selak, M. A., Unger, T. L., Keith, B., Liu, Q., Haase, V. H. 2009; 29 (16): 4527-4538


    In mammals, the liver integrates nutrient uptake and delivery of carbohydrates and lipids to peripheral tissues to control overall energy balance. Hepatocytes maintain metabolic homeostasis by coordinating gene expression programs in response to dietary and systemic signals. Hepatic tissue oxygenation is an important systemic signal that contributes to normal hepatocyte function as well as disease. Hypoxia-inducible factors 1 and 2 (HIF-1 and HIF-2, respectively) are oxygen-sensitive heterodimeric transcription factors, which act as key mediators of cellular adaptation to low oxygen. Previously, we have shown that HIF-2 plays an important role in both physiologic and pathophysiologic processes in the liver. HIF-2 is essential for normal fetal EPO production and erythropoiesis, while constitutive HIF-2 activity in the adult results in polycythemia and vascular tumorigenesis. Here we report a novel role for HIF-2 in regulating hepatic lipid metabolism. We found that constitutive activation of HIF-2 in the adult results in the development of severe hepatic steatosis associated with impaired fatty acid beta-oxidation, decreased lipogenic gene expression, and increased lipid storage capacity. These findings demonstrate that HIF-2 functions as an important regulator of hepatic lipid metabolism and identify HIF-2 as a potential target for the treatment of fatty liver disease.

    View details for DOI 10.1128/MCB.00200-09

    View details for Web of Science ID 000268310000016

    View details for PubMedID 19528226

  • Bringing H2AX into the Angiogenesis Family CANCER CELL Rankin, E. B., Giaccia, A. J., Hammond, E. M. 2009; 15 (6): 459-461


    The cell's ability to sense and respond to DNA damage is critical to maintain homeostasis and prevent the development of cancer. Paradoxically, Economopoulou et al. recently reported that a DNA damage response protein, H2AX, promotes tumor growth and angiogenesis.

    View details for DOI 10.1016/j.ccr.2009.05.004

    View details for Web of Science ID 000266686500003

    View details for PubMedID 19477424

    View details for PubMedCentralID PMC3408225

  • Stable expression of HIF-1 alpha in tubular epithelial cells promotes interstitial fibrosis AMERICAN JOURNAL OF PHYSIOLOGY-RENAL PHYSIOLOGY Kimura, K., Iwano, M., Higgins, D. F., Yamaguchi, Y., Nakatani, K., Harada, K., Kubo, A., Akai, Y., Rankin, E. B., Neilson, E. G., Haase, V. H., Saito, Y. 2008; 295 (4): F1023-F1029


    Chronic hypoxia accelerates renal fibrosis. The chief mediator of the hypoxic response is hypoxia-inducible factor 1 (HIF-1) and its oxygen-sensitive component HIF-1alpha. HIF-1 regulates a wide variety of genes, some of which are closely associated with tissue fibrosis. To determine the specific role of HIF-1 in renal fibrosis, we generated a knockout mouse in which tubular epithelial expression of von Hippel-Lindau tumor suppressor (VHL), which acts as a ubiquitin ligase to promote proteolysis of HIF-1alpha, was targeted. We investigated the effect of VHL deletion (i.e., stable expression of HIF-1alpha) histologically and used the anti-HIF-1alpha agent [3-(5'-hydroxymethyl-2'-furyl)-1-benzyl indazole] (YC-1) to test whether inhibition of HIF-1alpha could represent a novel approach to treating renal fibrosis. The area of renal fibrosis was significantly increased in a 5/6 renal ablation model of VHL-/- mice and in all VHL-/- mice at least 60 wk of age. Injection of YC-1 inhibited the progression of renal fibrosis in unilateral ureteral obstruction model mice. In conclusion, HIF-1alpha appears to be a critical contributor to the progression of renal fibrosis and could be a useful target for its treatment.

    View details for DOI 10.1152/ajprenal.90209.2008

    View details for Web of Science ID 000259913000019

    View details for PubMedID 18667485

  • Hypoxia-inducible factor-2 regulates vascular tumorigenesis in mice ONCOGENE Rankin, E. B., Rha, J., Unger, T. L., Wu, C. H., Shutt, H. P., Johnson, R. S., Simon, M. C., Keith, B., Haase, V. H. 2008; 27 (40): 5354-5358


    The von Hippel-Lindau tumor suppressor pVHL regulates the stability of hypoxia-inducible factors (HIF)-1 and -2, oxygen-sensitive basic helix-loop-helix transcription factors, which mediate the hypoxic induction of angiogenic growth factors such as vascular endothelial growth factor. Loss of pVHL function results in constitutive activation of HIF-1 and HIF-2 and is associated with the development of highly vascularized tumors in multiple organs. We have used a conditional gene-targeting approach to investigate the relative contributions of HIF-1 and HIF-2 to VHL-associated vascular tumorigenesis in a mouse model of liver hemangiomas. Here we demonstrate genetically that conditional inactivation of HIF-2alpha suppressed the development of VHL-associated liver hemangiomas and that angiogenic gene expression in hepatocytes is predominantly regulated by HIF-2 and not by HIF-1. These findings suggest that HIF-2 is the dominant HIF in the pathogenesis of VHL-associated vascular tumors and that pharmacologic targeting of HIF-2 may be an effective strategy for their treatment.

    View details for DOI 10.1038/onc.2008.160

    View details for Web of Science ID 000259096100008

    View details for PubMedID 18490920

  • The role of hypoxia-inducible factors in tumorigenesis CELL DEATH AND DIFFERENTIATION Rankin, E. B., Giaccia, A. J. 2008; 15 (4): 678-685


    Hypoxia-inducible factors (HIFs) are essential mediators of the cellular oxygen-signaling pathway. They are heterodimeric transcription factors consisting of an oxygen-sensitive alpha subunit (HIF-alpha) and a constitutive beta subunit (HIF-beta) that facilitate both oxygen delivery and adaptation to oxygen deprivation by regulating the expression of genes that control glucose uptake, metabolism, angiogenesis, erythropoiesis, cell proliferation, and apoptosis. In most experimental models, the HIF pathway is a positive regulator of tumor growth as its inhibition often results in tumor suppression. In clinical samples, HIF is found elevated and correlates with poor patient prognosis in a variety of cancers. In summary, HIF regulates multiple aspects of tumorigenesis, including angiogenesis, proliferation, metabolism, metastasis, differentiation, and response to radiation therapy, making it a critical regulator of the malignant phenotype.

    View details for DOI 10.1038/cdd.2008.21

    View details for Web of Science ID 000254041800010

    View details for PubMedID 18259193

    View details for PubMedCentralID PMC3050610

  • Regulation of iron homeostasis by the hypoxia-inducible transcription factors (HIFs) JOURNAL OF CLINICAL INVESTIGATION Peyssonnaux, C., Zinkernagel, A. S., Schuepbach, R. A., Rankin, E., Vaulont, S., Haase, V. H., Nizet, V., Johnson, R. S. 2007; 117 (7): 1926-1932


    Iron is essential for many biological processes, including oxygen delivery, and its supply is tightly regulated. Hepcidin, a small peptide synthesized in the liver, is a key regulator of iron absorption and homeostasis in mammals. Hepcidin production is increased by iron overload and decreased by anemia and hypoxia; but the molecular mechanisms that govern the hepcidin response to these stimuli are not known. Here we establish that the von Hippel-Lindau/hypoxia-inducible transcription factor (VHL/HIF) pathway is an essential link between iron homeostasis and hepcidin regulation in vivo. Through coordinate downregulation of hepcidin and upregulation of erythropoietin and ferroportin, the VHL-HIF pathway mobilizes iron to support erythrocyte production.

    View details for DOI 10.1172/JCI31370

    View details for Web of Science ID 000247837700024

    View details for PubMedID 17557118

  • Hypoxia-inducible factor-2 (HIF-2) regulates hepatic erythropoietin in vivo JOURNAL OF CLINICAL INVESTIGATION Rankin, E. B., Biju, M. P., Liu, Q., Unger, T. L., Rha, J., Johnson, R. S., Simon, M. C., Keith, B., Haase, V. H. 2007; 117 (4): 1068-1077


    Erythropoiesis is critically dependent on erythropoietin (EPO), a glycoprotein hormone that is regulated by hypoxia-inducible factor (HIF). Hepatocytes are the primary source of extrarenal EPO in the adult and express HIF-1 and HIF-2, whose roles in the hypoxic induction of EPO remain controversial. In order to define the role of HIF-1 and HIF-2 in the regulation of hepatic EPO expression, we have generated mice with conditional inactivation of Hif-1alpha and/or Hif-2alpha (Epas1) in hepatocytes. We have previously shown that inactivation of the von Hippel-Lindau tumor suppressor pVHL, which targets both HIFs for proteasomal degradation, results in increased hepatic Epo production and polycythemia independent of Hif-1alpha. Here we show that conditional inactivation of Hif-2alpha in pVHL-deficient mice suppressed hepatic Epo and the development of polycythemia. Furthermore, we found that physiological Epo expression in infant livers required Hif-2alpha but not Hif-1alpha and that the hypoxic induction of liver Epo in anemic adults was Hif-2alpha dependent. Since other Hif target genes such phosphoglycerate kinase 1 (Pgk) were Hif-1alpha dependent, we provide genetic evidence that HIF-1 and HIF-2 have distinct roles in the regulation of hypoxia-inducible genes and that EPO is preferentially regulated by HIF-2 in the liver.

    View details for DOI 10.1172/JCI30117

    View details for Web of Science ID 000245451700029

    View details for PubMedID 17404621

  • Rend cyst development in mice with conditional inactivation of the von Hippel-Lindau tumor suppressor CANCER RESEARCH Rankin, E. B., Tomaszewski, J. E., Haase, V. H. 2006; 66 (5): 2576-2583


    Inactivation of the von Hippel-Lindau tumor suppressor, pVHL, is associated with both hereditary and sporadic renal cysts and renal cell carcinoma, which are commonly thought to arise from the renal proximal tubule. pVHL regulates the protein stability of hypoxia-inducible factor (HIF)-alpha subunits and loss of pVHL function leads to HIF stabilization. The role of HIF in the development of VHL-associated renal lesions remains to be determined. To investigate the functional consequences of pVHL inactivation and the role of HIF signaling in renal epithelial cells, we used the phosphoenolpyruvate carboxykinase (PEPCK) promoter to generate transgenic mice in which Cre-recombinase is expressed in the renal proximal tubule and in hepatocytes. We found that conditional inactivation of VHL in PEPCK-Cre mutants resulted in renal cyst development that was associated with increased erythropoietin levels and polycythemia. Increased expression of the HIF target gene erythropoietin was limited to the liver, whereas expression of carbonic anhydrase 9 and multidrug resistance gene 1 was up-regulated in the renal cortex of mutant mice. Inactivation of the HIF-alpha binding partner, arylhydrocarbon receptor nuclear translocator (Arnt), but not Hif-1alpha, suppressed the development of renal cysts. Here, we present the first mouse model of VHL-associated renal disease that will provide a basis for further genetic studies to define the molecular events that are required for the progression of VHL-associated renal cysts to clear cell renal cell carcinoma.

    View details for DOI 10.1158/0008-5472.CAN-05-3241

    View details for Web of Science ID 000235826400014

    View details for PubMedID 16510575

  • Inactivation of the arylhydrocarbon receptor nuclear translocator (Arnt) suppresses von Hippel-Lindau disease-associated vascular tumors in mice MOLECULAR AND CELLULAR BIOLOGY Rankin, E. B., Higgins, D. F., Walisser, J. A., Johnson, R. S., Bradfield, C. A., Haase, V. H. 2005; 25 (8): 3163-3172


    Patients with germ line mutations in the VHL tumor suppressor gene are predisposed to the development of highly vascularized tumors within multiple tissues. Loss of pVHL results in constitutive activation of the transcription factors HIF-1 and HIF-2, whose relative contributions to the pathogenesis of the VHL phenotype have yet to be defined. In order to examine the role of HIF in von Hippel-Lindau (VHL)-associated vascular tumorigenesis, we utilized Cre-loxP-mediated recombination to inactivate hypoxia-inducible factor-1alpha (Hif-1alpha) and arylhydrocarbon receptor nuclear translocator (Arnt) genes in a VHL mouse model of cavernous liver hemangiomas and polycythemia. Deletion of Hif-1alpha did not affect the development of vascular tumors and polycythemia, nor did it suppress the increased expression of vascular endothelial growth factor (Vegf) and erythropoietin (Epo). In contrast, phosphoglycerokinase (Pgk) expression was substantially decreased, providing evidence for target gene-dependent functional redundancy between different Hif transcription factors. Inactivation of Arnt completely suppressed the development of hemangiomas, polycythemia, and Hif-induced gene expression. Here, we demonstrate genetically that the development of VHL-associated vascular tumors in the liver depends on functional ARNT. Furthermore, we provide evidence that individual HIF transcription factors may play distinct roles in the development of specific VHL disease manifestations.

    View details for DOI 10.1128/MCB.25.8.3163-3172.2005

    View details for Web of Science ID 000228138500025

    View details for PubMedID 15798202

  • Putative intestine-specific enhancers located in 5 ' sequence of the CDX1 gene regulate CDX1 expression in the intestine AMERICAN JOURNAL OF PHYSIOLOGY-GASTROINTESTINAL AND LIVER PHYSIOLOGY Rankin, E. B., Xu, W., Silberg, D. G., Suh, E. 2004; 286 (5): G872-G880


    CDX1 is a homeobox transcription factor that plays a critical role in intestinal epithelial cell growth and differentiation. CDX1 gene expression is tightly regulated in a temporal and cell-type specific manner. However, very little is known about the regulatory mechanisms that direct CDX1 gene expression in the intestine. To elucidate these mechanisms, we employed a series of transgenic mouse studies using the 5' flanking sequences of the human CDX1 gene. Transgenic mice containing nucleotides between -5667 and +68 relative to the transcription start site of the CDX1 gene demonstrated ectopic expression of the transgene in the brain and gastric smooth muscle. However, transgenic expression of the nucleotides -15601 to +68 of the CDX1 gene was restricted to the intestinal epithelium, which was identical to endogenous CDX1 gene expression. Taken together, the upstream sequences between -15601 and -5667 contain regulatory elements that direct transgene expression specifically to the intestinal epithelium. Furthermore, DNase I hypersensitivity assays revealed two active chromatin regions in the CDX1 gene (hypertensive sites 1 and 2) located at approximately -5.8 and -6.8 kb upstream of the CDX1 gene, respectively, which may function as potential intestine-specific enhancers.

    View details for DOI 10.1152/ajpgi.00326.2003

    View details for Web of Science ID 000220693200023

    View details for PubMedID 14715525

  • An essential role of Th1 responses and interferon gamma in infection-mediated suppression of neoplastic growth CANCER BIOLOGY & THERAPY Rankin, E. B., Yu, D. N., Jiang, J., Shen, H., Pearce, E. J., Goldschmidt, M. H., Levy, D. E., Golovkina, T. V., Hunter, C. A., Thomas-Tikhonenko, A. 2003; 2 (6): 687-693


    We had previously demonstrated that in mice acute toxoplasmosis leads to systemic inhibition of angiogenesis and, consequently, strong suppression of neoplastic growth. Here we investigated the role of Th1 cytokines, in particular interferon gamma (IFN-gamma), in this phenomenon. Besides toxoplasma, neoplastic growth was readily blocked during acute infection with other Th1 response-inducing pathogens such as Listeria monocytogenes and lymphocytic choriomeningitis virus (LCMV). In contrast, chronic infection with LCMV (when Th1 responses were strongly suppressed) and acute infection with Schistosoma mansoni (when Th2 responses predominated) afforded no anti-tumor protection. To corroborate the involvement of Th1 cytokines in infection-mediated suppression of neoplastic growth, we utilized mice deficient in interleukin-10 (IL10), a suppressor of Th1 responses. When challenged with B16 cells concomitantly with toxoplasma infection, both IL10-null and wild type mice exhibited resistance to neoplastic growth. However, tumors borne by IL10-null animals were even smaller than those borne by their wild type counterparts. This enhanced resistance correlated with dramatically elevated levels of circulating IFN-gamma, a principal Th1 cytokine. Furthermore, while interleukin-12 and tumor necrosis factor a were dispensable for tumor suppression, in animals deficient in IFN-gamma production or signaling, tumor growth and neovascularization were markedly enhanced. Interestingly, the enhancement was also apparent in uninfected animals suggesting that IFN-gamma and its anti-angiogenic effects underlie both infection-dependent and -independent tumor surveillance.

    View details for Web of Science ID 000188846200017

    View details for PubMedID 14688478

  • DNA methylation down-regulates CDX1 gene expression in colorectal cancer cell lines JOURNAL OF BIOLOGICAL CHEMISTRY Suh, E. R., Ha, C. S., Rankin, E. B., Toyota, M., Traber, P. G. 2002; 277 (39): 35795-35800


    CDX1 is a homeobox protein that inhibits proliferation of intestinal epithelial cells and regulates intestine-specific genes involved in differentiation. CDX1 expression is developmentally and spatially regulated, and its expression is aberrantly down-regulated in colorectal cancers and colon cancer-derived cell lines. However, very little is known about the molecular mechanism underlying the regulation of CDX1 gene expression. In this study, we characterized the CDX1 gene structure and identified that its gene promoter contained a typical CpG island with a CpG observed/expected ratio of 0.80, suggesting that the CDX1 gene is a target of aberrant methylation. Alterations of DNA methylation in the CDX1 gene promoter were investigated in a series of colorectal cancer cell lines. Combined Bisulfite Restriction Analysis (COBRA) and bisulfite sequencing analysis revealed that the CDX1 promoter is methylated in CDX1 non-expressing colorectal cancer cell lines but not in human normal colon tissue and T84 cells, which express CDX1. Treatment with 5'-aza-2'-deoxycytidine (5-azaC), a DNA methyltransferase inhibitor, induced CDX1 expression in the colorectal cancer cell lines. Furthermore, de novo methylation was determined by establishing stably transfected clones of the CDX1 promoter in SW480 cells and demethylation by 5-azaC-activated reporter gene expression. These results indicate that aberrant methylation of the CpG island in the CDX1 promoter is one of the mechanisms that mediate CDX1 down-regulation in colorectal cancer cell lines.

    View details for DOI 10.1074/jbc.M205567200

    View details for Web of Science ID 000178275100005

    View details for PubMedID 12124393