All Publications

  • Characterizing Moral Injury and Distress in US Military Surgeons Deployed to Far-Forward Combat Environments in Afghanistan and Iraq. JAMA network open Ryu, M. Y., Martin, M. J., Jin, A. H., Tabor, H. K., Wren, S. M. 2023; 6 (2): e230484


    Importance: Moral injury and distress (MID), which occurs when individuals have significant dissonance with their belief system and overwhelming feelings of being powerless to do what is believed to be right, has not been explored in the unique population of military surgeons deployed far forward in active combat settings. Deployed military surgeons provide care to both injured soldiers and civilians under command-driven medical rules of engagement (MROE) in variably resourced settings. This practice setting has no civilian corollary for comparison or current specific tool for measurement.Objective: To characterize MID among military surgeons deployed during periods of high casualty volumes through a mixed-methods approach.Design, Setting, and Participants: This qualitative study using convergent mixed methods was performed from May 2020 to October 2020. Participants included US military surgeons who had combat deployments to a far-forward role 2 treatment facility during predefined peak casualty periods in Iraq (2003-2008) and Afghanistan (2009-2012), as identified by purposeful snowball sampling. Data analysis was performed from October 2020 to May 2021.Main Outcomes and Measures: Measure of Moral Distress for Healthcare Professionals (MMD-HP) survey and individual, semistructured interviews were conducted to thematic saturation.Results: The total cohort included 20 surgeons (mean [SD] age, 38.1 [5.2] years); 16 (80%) were male, and 16 (80%) had 0 or 1 prior deployment. Deployment locations were Afghanistan (11 surgeons [55%]), Iraq (9 surgeons [45%]), or both locations (3 surgeons [15%]). The mean (SD) MMD-HP score for the surgeons was 104.1 (39.3). The primary thematic domains for MID were distressing outcomes (DO) and MROE. The major subdomains of DO were guilt related to witnessing horrific injuries; treating pregnant women, children, and US soldiers; and second-guessing decisions. The major subdomains for MROE were forced transfer of civilian patients, limited capabilities and resources, inexperience in specialty surgical procedures, and communication with command. Postdeployment manifestations of MID were common and affected sleep, medical practice, and interpersonal relationships.Conclusions and Relevance: In this qualitative study, MID was ubiquitous in deployed military surgeons. Thematic observations about MID, specifically concerning the domains of DO and MROE, may represent targets for further study to develop an evaluation tool of MID in this population and inform possible programs for identification and mitigation of MID.

    View details for DOI 10.1001/jamanetworkopen.2023.0484

    View details for PubMedID 36821112

  • Therapeutic targeting of LCK tyrosine kinase and mTOR signaling in T-cell acute lymphoblastic leukemia BLOOD Laukkanen, S., Veloso, A., Yan, C., Oksa, L., Alpert, E. J., Do, D., Hyvarinen, N., McCarthy, K., Adhikari, A., Yang, Q., Iyer, S., Garcia, S. P., Pello, A., Ruokoranta, T., Moisio, S., Adhikari, S., Yoder, J. A., Gallagher, K., Whelton, L., Allen, J. R., Jin, A. H., Loontiens, S., Heinaniemi, M., Kelliher, M., Heckman, C. A., Lohi, O., Langenau, D. M. 2022; 140 (17): 1891-1906


    Relapse and refractory T-cell acute lymphoblastic leukemia (T-ALL) has a poor prognosis, and new combination therapies are sorely needed. Here, we used an ex vivo high-throughput screening platform to identify drug combinations that kill zebrafish T-ALL and then validated top drug combinations for preclinical efficacy in human disease. This work uncovered potent drug synergies between AKT/mTORC1 (mammalian target of rapamycin complex 1) inhibitors and the general tyrosine kinase inhibitor dasatinib. Importantly, these same drug combinations effectively killed a subset of relapse and dexamethasone-resistant zebrafish T-ALL. Clinical trials are currently underway using the combination of mTORC1 inhibitor temsirolimus and dasatinib in other pediatric cancer indications, leading us to prioritize this therapy for preclinical testing. This combination effectively curbed T-ALL growth in human cell lines and primary human T-ALL and was well tolerated and effective in suppressing leukemia growth in patient-derived xenografts (PDX) grown in mice. Mechanistically, dasatinib inhibited phosphorylation and activation of the lymphocyte-specific protein tyrosine kinase (LCK) to blunt the T-cell receptor (TCR) signaling pathway, and when complexed with mTORC1 inhibition, induced potent T-ALL cell killing through reducing MCL-1 protein expression. In total, our work uncovered unexpected roles for the LCK kinase and its regulation of downstream TCR signaling in suppressing apoptosis and driving continued leukemia growth. Analysis of a wide array of primary human T-ALLs and PDXs grown in mice suggest that combination of temsirolimus and dasatinib treatment will be efficacious for a large fraction of human T-ALLs.

    View details for Web of Science ID 000922881000007

    View details for PubMedID 35544598

  • Single-cell analysis and functional characterization uncover the stem cell hierarchies and developmental origins of rhabdomyosarcoma NATURE CANCER Wei, Y., Qin, Q., Yan, C., Hayes, M. N., Garcia, S. P., Xi, H., Do, D., Jin, A. H., Eng, T. C., McCarthy, K. M., Adhikari, A., Onozato, M. L., Spentzos, D., Neilsen, G. P., Iafrate, A., Wexler, L. H., Pyle, A. D., Suva, M. L., Dela Cruz, F., Pinello, L., Langenau, D. M. 2022: 961-975


    Rhabdomyosarcoma (RMS) is a common childhood cancer that shares features with developing skeletal muscle. Yet, the conservation of cellular hierarchy with human muscle development and the identification of molecularly defined tumor-propagating cells has not been reported. Using single-cell RNA-sequencing, DNA-barcode cell fate mapping and functional stem cell assays, we uncovered shared tumor cell hierarchies in RMS and human muscle development. We also identified common developmental stages at which tumor cells become arrested. Fusion-negative RMS cells resemble early myogenic cells found in embryonic and fetal development, while fusion-positive RMS cells express a highly specific gene program found in muscle cells transiting from embryonic to fetal development at 7-7.75 weeks of age. Fusion-positive RMS cells also have neural pathway-enriched states, suggesting less-rigid adherence to muscle-lineage hierarchies. Finally, we identified a molecularly defined tumor-propagating subpopulation in fusion-negative RMS that shares remarkable similarity to bi-potent, muscle mesenchyme progenitors that can make both muscle and osteogenic cells.

    View details for DOI 10.1038/s43018-022-00414-w

    View details for Web of Science ID 000842199400001

    View details for PubMedID 35982179

  • Implementation of a clinic to facilitate the transition from pediatric to adult cancer survivorship care. Smith, S. M., Jin, A., Simon, P., Clayton, A., Benedict, C., Liedtke, M., Muffly, L. S., Schapira, L. LIPPINCOTT WILLIAMS & WILKINS. 2021
  • tp53 deficiency causes a wide tumor spectrum and increases embryonal rhabdomyosarcoma metastasis in zebrafish. eLife Ignatius, M. S., Hayes, M. N., Moore, F. E., Tang, Q., Garcia, S. P., Blackburn, P. R., Baxi, K., Wang, L., Jin, A., Ramakrishnan, A., Reeder, S., Chen, Y., Nielsen, G. P., Chen, E. Y., Hasserjian, R. P., Tirode, F., Ekker, S. C., Langenau, D. M. 2018; 7


    The TP53 tumor-suppressor gene is mutated in >50% of human tumors and Li-Fraumeni patients with germ line inactivation are predisposed to developing cancer. Here, we generated tp53 deleted zebrafish that spontaneously develop malignant peripheral nerve-sheath tumors, angiosarcomas, germ cell tumors, and an aggressive Natural Killer cell-like leukemia for which no animal model has been developed. Because the tp53 deletion was generated in syngeneic zebrafish, engraftment of fluorescent-labeled tumors could be dynamically visualized over time. Importantly, engrafted tumors shared gene expression signatures with predicted cells of origin in human tissue. Finally, we showed that tp53 del/del enhanced invasion and metastasis in kRASG12D-induced embryonal rhabdomyosarcoma (ERMS), but did not alter the overall frequency of cancer stem cells, suggesting novel pro-metastatic roles for TP53 loss-of-function in human muscle tumors. In summary, we have developed a Li-Fraumeni zebrafish model that is amenable to large-scale transplantation and direct visualization of tumor growth in live animals.

    View details for DOI 10.7554/eLife.37202

    View details for PubMedID 30192230

    View details for PubMedCentralID PMC6128690

  • Vangl2 regulates cancer stem cell self-renewal and growth in rhabdomyosarcoma Hayes, M., McCarthy, K., Jin, A., Iyer, S., Garcia, S., Oliveira, M. L., Sindiri, S., Gryder, B., Motala, Z., Nielsen, G., Borg, J., van de Rijn, M., Malkin, D., Khan, J., Ignatius, M., Langenau, D. M. AMER ASSOC CANCER RESEARCH. 2018
  • Vangl2/RhoA Signaling Pathway Regulates Stem Cell Self-Renewal Programs and Growth in Rhabdomyosarcoma CELL STEM CELL Hayes, M. N., McCarthy, K., Jin, A., Oliveira, M. L., Iyer, S., Garcia, S. P., Sindiri, S., Gryder, B., Motala, Z., Nielsen, G., Borg, J., De Rijn, M., Malkin, D., Khan, J., Ignatius, M. S., Langenau, D. M. 2018; 22 (3): 414-+


    Tumor growth and relapse are driven by tumor propagating cells (TPCs). However, mechanisms regulating TPC fate choices, maintenance, and self-renewal are not fully understood. Here, we show that Van Gogh-like 2 (Vangl2), a core regulator of the non-canonical Wnt/planar cell polarity (Wnt/PCP) pathway, affects TPC self-renewal in rhabdomyosarcoma (RMS)-a pediatric cancer of muscle. VANGL2 is expressed in a majority of human RMS and within early mononuclear progenitor cells. VANGL2 depletion inhibited cell proliferation, reduced TPC numbers, and induced differentiation of human RMS in vitro and in mouse xenografts. Using a zebrafish model of embryonal rhabdomyosarcoma (ERMS), we determined that Vangl2 expression enriches for TPCs and promotes their self-renewal. Expression of constitutively active and dominant-negative isoforms of RHOA revealed that it acts downstream of VANGL2 to regulate proliferation and maintenance of TPCs in human RMS. Our studies offer insights into pathways that control TPCs and identify new potential therapeutic targets.

    View details for PubMedID 29499154

  • The NOTCH1/SNAIL1/MEF2C Pathway Regulates Growth and Self-Renewal in Embryonal Rhabdomyosarcoma. Cell reports Ignatius, M. S., Hayes, M. N., Lobbardi, R., Chen, E. Y., McCarthy, K. M., Sreenivas, P., Motala, Z., Durbin, A. D., Molodtsov, A., Reeder, S., Jin, A., Sindiri, S., Beleyea, B. C., Bhere, D., Alexander, M. S., Shah, K., Keller, C., Linardic, C. M., Nielsen, P. G., Malkin, D., Khan, J., Langenau, D. M. 2017; 19 (11): 2304-2318


    Tumor-propagating cells (TPCs) share self-renewal properties with normal stem cells and drive continued tumor growth. However, mechanisms regulating TPC self-renewal are largely unknown, especially in embryonal rhabdomyosarcoma (ERMS)-a common pediatric cancer of muscle. Here, we used a zebrafish transgenic model of ERMS to identify a role for intracellular NOTCH1 (ICN1) in increasing TPCs by 23-fold. ICN1 expanded TPCs by enabling the de-differentiation of zebrafish ERMS cells into self-renewing myf5+ TPCs, breaking the rigid differentiation hierarchies reported in normal muscle. ICN1 also had conserved roles in regulating human ERMS self-renewal and growth. Mechanistically, ICN1 upregulated expression of SNAIL1, a transcriptional repressor, to increase TPC number in human ERMS and to block muscle differentiation through suppressing MEF2C, a myogenic differentiation transcription factor. Our data implicate the NOTCH1/SNAI1/MEF2C signaling axis as a major determinant of TPC self-renewal and differentiation in ERMS, raising hope of therapeutically targeting this pathway in the future.

    View details for DOI 10.1016/j.celrep.2017.05.061

    View details for PubMedID 28614716

    View details for PubMedCentralID PMC5563075