Honors & Awards
NCI R37 MERIT Award, National Cancer Institute (2020-2025)
Society for Basic Urologic Research (SBUR) Young Investigator Award, Society for Basic Urologic Research (2020)
Idea Development Award, Department of Defense, Prostate Cancer Research Program (2018-2021)
McCormick and Gabilan Faculty Award, Stanford University (2016-2018)
K99/R00 Pathway to Independence Award, National Institutes of Health/National Cancer Institute (2014-2019)
2014 Stewart Rahr Prostate Cancer Foundation Young Investigator Award, Prostate Cancer Foundation (2014-2017)
2014 Department of Pharmacology Retreat Award, University of California, Los Angeles, CA (2014)
Chancellor's Award for Postdoctoral Research, University of California, Los Angeles, CA (2014)
Postdoctoral Fellowship. Prostate Cancer Research Program, Department of Defense (2012-2014)
Postdoctoral Fellowship, California Institute for Regenerative Medicine (2010-2012)
SIGMA Xi Student Research Forum Award for Graduate and Professional Students 2008, University of Illinois, Chicago, IL (2008)
SIGMA Xi Student Research Forum Award for Graduate and Professional Students 2007, University of Illinois, Chicago, IL (2007)
Sally Frost Mason Outstanding Woman Student in Biological Sciences 2003, University of Kansas, Lawrence, KS (2003)
Sally K. Frost Mason and Kenneth A. Mason Outstanding Senior 2003. Division of Biological Sciences, University of Kansas, Lawrence, KS (2003)
Ruben Zadigan Environmental Studies Scholarship, University of Kansas, Lawrence, KS (2001-2003)
Postdoctoral Fellowships, University of California, Los Angeles, CA, USA, Stem cell and Cancer Biology (2015)
PhD, University of Illinois, Chicago, IL, USA, Biochemistry and Molecular Genetics (2009)
BS, University of Kansas, Lawrence, KS, USA, Genetics (2003)
BS, Technical University of Varna, Varna, Bulgaria, Ecology and Protection of the Environment (2002)
Meghan A. Rice, Vineet Kumar, Dhanir Tailor , Sanjay V. Malhotra and Tanya Stoyanova. "United States Patent 17/307,699 Methoxychalcone Derivative and Uses Thereof", Leland Stanford Junior University
Current Research and Scholarly Interests
Stoyanova lab develops new early cancer detection methods and therapeutic strategies for late stage cancers. The current research focus is on protein-based biomarkers for early cancer detection as well as development of new small molecule inhibitors and antibody-based therapies for prostate and other epithelial cancers. The ultimate goals of the laboratory are to improve the early diagnosis and prognosis of clinically significant cancers and guide the development of novel and effective therapeutic strategies for metastatic prostate and other epithelial cancers.
- Analytical Methods in Biotechnology
EE 235A (Win)
- Analytical Methods in Biotechnology II
EE 235B (Spr)
Independent Studies (8)
- Directed Reading in Radiology
RAD 299 (Win, Spr)
- Early Clinical Experience in Radiology
RAD 280 (Win, Spr)
- Graduate Research
RAD 399 (Win, Spr)
- Medical Scholars Research
RAD 370 (Win, Spr)
- Out-of-Department Advanced Research Laboratory in Bioengineering
BIOE 191X (Aut, Spr)
- Out-of-Department Undergraduate Research
BIO 199X (Spr)
- Readings in Radiology Research
RAD 101 (Win, Spr)
- Undergraduate Research
RAD 199 (Aut, Win, Spr)
- Directed Reading in Radiology
- Prior Year Courses
Graduate and Fellowship Programs
- Volbots: Volvox Microalgae-Based Robots for Multimode Precision Imaging and Therapy ADVANCED FUNCTIONAL MATERIALS 2022
Metastasis Model to Test the Role of Notch Signaling in Prostate Cancer.
Methods in molecular biology (Clifton, N.J.)
2022; 2472: 221-233
Distant metastasis is the main cause of death in prostate cancer patients. Notch signaling plays an important role in driving prostate cancer aggressiveness and metastasis. In this chapter, we describe a protocol to measure prostate cancer metastatic colonization, incidences of metastasis, accurately quantify the burden of metastasis, and test the role of NOTCH1 receptor on prostate cancer metastatic colonization and homing to distant sites. The metastasis model presented here is established by intracardiac injection of control human prostate cancer cells and NOTCH1 downregulated cells. The cells are engineered to express both red fluorescent protein (RFP) and luciferase. In this model, whole body bioluminescence imaging, high-resolution, and quantitative fluorescence imaging are utilized for quantitative assessment of metastatic colonization and metastasis burden. Further, histopathology analyses of diverse metastatic organs are performed. This model is a powerful and versatile tool to investigate the mechanisms underlying the function of NOTCH receptors in metastatic colonization in prostate cancer.
View details for DOI 10.1007/978-1-0716-2201-8_18
View details for PubMedID 35674904
Acoustic Fabrication of Living Cardiomyocyte-based Hybrid Biorobots.
Organized assemblies of cells have demonstrated promise as bioinspired actuators and devices; still, the fabrication of such "biorobots" has predominantly relied on passive assembly methods that reduce design capabilities. To address this, we have developed a strategy for the rapid formation of functional biorobots composed of live cardiomyocytes. We employ tunable acoustic fields to facilitate the efficient aggregation of millions of cells into high-density macroscopic architectures with directed cell orientation and enhanced cell-cell interaction. These biorobots can perform actuation functions both through naturally occurring contraction-relaxation cycles and through external control with chemical and electrical stimuli. We demonstrate that these biorobots can be used to achieve controlled actuation of a soft skeleton and pumping of microparticles. The biocompatible acoustic assembly strategy described here should prove generally useful for cellular manipulation in the context of tissue engineering, soft robotics, and other applications.
View details for DOI 10.1021/acsnano.2c01908
View details for PubMedID 35671037
Molecular Mechanisms Underlying the Development of Neuroendocrine Prostate Cancer.
Seminars in cancer biology
Prostate cancer is the most common non-cutaneous cancer and the second leading cause of cancer-associated deaths among men in the United States. Androgen deprivation therapy (ADT) is the standard of care for advanced prostate cancer. While patients with advanced prostate cancer initially respond to ADT, the disease frequently progresses to a lethal metastatic form, defined as castration-resistant prostate cancer (CRPC). After multiple rounds of anti-androgen therapies, 20-25% of metastatic CRPCs develop a neuroendocrine (NE) phenotype. These tumors are classified as neuroendocrine prostate cancer (NEPC). De novo NEPC is rare and accounts for less than 2% of all prostate cancers at diagnosis. NEPC is commonly characterized by the expression of NE markers and the absence of androgen receptor (AR) expression. NEPC is usually associated with tumor aggressiveness, hormone therapy resistance, and poor clinical outcome. Here, we review the molecular mechanisms underlying the emergence of NEPC and provide insights into the future perspectives on potential therapeutic strategies for NEPC.
View details for DOI 10.1016/j.semcancer.2022.05.007
View details for PubMedID 35597438
Correlation of 68Ga-RM2 PET with Post-Surgery Histopathology Findings in Patients with Newly Diagnosed Intermediate- or High-Risk Prostate Cancer.
Journal of nuclear medicine : official publication, Society of Nuclear Medicine
Rationale: 68Ga-RM2 targets gastrin-releasing peptide receptors (GRPR), which are overexpressed in prostate cancer (PC). Here, we compared pre-operative 68Ga-RM2 PET to post-surgery histopathology in patients with newly diagnosed intermediate- or high-risk PC. Methods: Forty-one men, 64.0+/-6.7-year-old, were prospectively enrolled. PET images were acquired 42 - 72 (median+/-SD 52.5+/-6.5) minutes after injection of 118.4 - 247.9 (median+/-SD 138.0+/-22.2)MBq of 68Ga-RM2. PET findings were compared to pre-operative mpMRI (n = 36) and 68Ga-PSMA11 PET (n = 17) and correlated to post-prostatectomy whole-mount histopathology (n = 32) and time to biochemical recurrence. Nine participants decided to undergo radiation therapy after study enrollment. Results: All participants had intermediate (n = 17) or high-risk (n = 24) PC and were scheduled for prostatectomy. Prostate specific antigen (PSA) was 8.8+/-77.4 (range 2.5 - 504) ng/mL, and 7.6+/-5.3 (range 2.5 - 28.0) ng/mL when excluding participants who ultimately underwent radiation treatment. Pre-operative 68Ga-RM2 PET identified 70 intraprostatic foci of uptake in 40/41 patients. Post-prostatectomy histopathology was available in 32 patients in which 68Ga-RM2 PET identified 50/54 intraprostatic lesions (detection rate = 93%). 68Ga-RM2 uptake was recorded in 19 non-enlarged pelvic lymph nodes in 6 patients. Pathology confirmed lymph node metastases in 16 lesions, and follow-up imaging confirmed nodal metastases in 2 lesions. 68Ga-PSMA11 and 68Ga-RM2 PET identified 27 and 26 intraprostatic lesions, respectively, and 5 pelvic lymph nodes each in 17 patients. Concordance between 68Ga-RM2 and 68Ga-PSMA11 PET was found in 18 prostatic lesions in 11 patients, and 4 lymph nodes in 2 patients. Non-congruent findings were observed in 6 patients (intraprostatic lesions in 4 patients and nodal lesions in 2 patients). Both 68Ga-RM2 and 68Ga-PSMA11 had higher sensitivity and accuracy rates with 98%, 89%, and 95%, 89%, respectively, compared to mpMRI at 77% and 77%. Specificity was highest for mpMRI with 75% followed by 68Ga-PSMA11 (67%), and 68Ga-RM2 (65%). Conclusion: 68Ga-RM2 PET accurately detects intermediate- and high-risk primary PC with a detection rate of 93%. In addition, it showed significantly higher specificity and accuracy compared to mpMRI and similar performance to 68Ga-PSMA11 PET. These findings need to be confirmed in larger studies to identify which patients will benefit from one or the other or both radiopharmaceuticals.
View details for DOI 10.2967/jnumed.122.263971
View details for PubMedID 35552245
SU086, an inhibitor of HSP90, impairs glycolysis and represents a treatment strategy for advanced prostate cancer.
Cell reports. Medicine
2022; 3 (2): 100502
Among men, prostate cancer is the second leading cause of cancer-associated mortality, with advanced disease remaining a major clinical challenge. We describe a small molecule, SU086, as a therapeutic strategy for advanced prostate cancer. We demonstrate that SU086 inhibits the growth of prostate cancer cells invitro, cell-line and patient-derived xenografts invivo, and exvivo prostate cancer patient specimens. Furthermore, SU086 in combination with standard of care second-generation anti-androgen therapies displays increased impairment of prostate cancer cell and tumor growth invitro and invivo. Cellular thermal shift assay reveals that SU086 binds to heat shock protein 90 (HSP90) and leads to a decrease in HSP90 levels. Proteomic profiling demonstrates that SU086 binds to and decreases HSP90. Metabolomic profiling reveals that SU086 leads to perturbation of glycolysis. Our study identifies SU086 as a treatment for advanced prostate cancer as a single agent or when combined with second-generation anti-androgens.
View details for DOI 10.1016/j.xcrm.2021.100502
View details for PubMedID 35243415
Protein signatures to distinguish aggressive from indolent prostate cancer.
Distinguishing men with aggressive from indolent prostate cancer is critical to decisions in the management of clinically localized prostate cancer. Molecular signatures of aggressive disease could help men overcome this major clinical challenge by reducing unnecessary treatment and allowing more appropriate treatment of aggressive disease.We performed a mass spectrometry-based proteomic analysis of normal and malignant prostate tissues from 22 men who underwent surgery for prostate cancer. Prostate cancer samples included Grade Groups (3-5), with 8 patients experiencing recurrence and 14 without evidence of recurrence with a mean of 6.8 years of follow-up. To better understand the biological pathways underlying prostate cancer aggressiveness, we performed a systems biology analysis and gene enrichment analysis. Proteins that distinguished recurrent from nonrecurrent cancer were chosen for validation by immunohistochemical analysis on tissue microarrays containing samples from a larger cohort of patients with recurrent and nonrecurrent prostate cancer.In all, 24,037 unique peptides (false discovery rate < 1%) corresponding to 3,313 distinct proteins were identified with absolute abundance ranges spanning seven orders of magnitude. Of these proteins, 115 showed significantly (p < 0.01) different levels in tissues from recurrent versus nonrecurrent cancers. Analysis of all differentially expressed proteins in recurrent and nonrecurrent cases identified several protein networks, most prominently one in which approximately 24% of the proteins in the network were regulated by the YY1 transcription factor (adjusted p < 0.001). Strong immunohistochemical staining levels of three differentially expressed proteins, POSTN, CALR, and CTSD, on a tissue microarray validated their association with shorter patient survival.The protein signatures identified could improve understanding of the molecular drivers of aggressive prostate cancer and be used as candidate prognostic biomarkers.
View details for DOI 10.1002/pros.24307
View details for PubMedID 35098564
Identifying a novel glycolytic inhibitor for treatment of aggressive prostate cancer.
AMER ASSOC CANCER RESEARCH. 2021
View details for Web of Science ID 000680263506119
Trop2 regulates prostate cancer growth and metastasis through distinct molecular mechanisms.
AMER ASSOC CANCER RESEARCH. 2021
View details for Web of Science ID 000680263502050
MCM2-7 complex is a novel druggable target for neuroendocrine prostate cancer.
AMER ASSOC CANCER RESEARCH. 2021
View details for Web of Science ID 000680263504261
A novel oncogene mediated metabolic gene signature predicts breast cancer outcome.
AMER ASSOC CANCER RESEARCH. 2021
View details for Web of Science ID 000680263505341
Ferroptosis inducers are a novel therapeutic approach for advanced prostate cancer.
Ferroptosis is a type of programmed cell death induced by the accumulation of lipid peroxidation and lipid reactive oxygen species (ROS) in cells. It has been recently demonstrated that cancer cells are vulnerable to ferroptosis inducers (FIN). However, the therapeutic potential of ferroptosis inducers in prostate cancer in pre-clinical settings has not been explored. In this study, we demonstrate that mediators of ferroptosis SLC7A11, SLC3A2 and GPX4 are expressed in treatment-resistant prostate cancer. We further demonstrate that treatment-resistant prostate cancer cells are sensitive to two ferroptosis inducers, erastin and RSL3. Treatment with erastin and RSL3 led to a significant decrease in prostate cancer cell growth and migration in vitro and significantly delayed the tumor growth of treatment-resistant prostate cancer in vivo, with no measurable side effects. Combination of erastin or RSL3 with standard-of-care second-generation anti-androgens for advanced prostate cancer halted prostate cancer cell growth and migration in vitro and tumor growth in vivo. These results demonstrate the potential of erastin or RSL3 independently and in combination with standard-of-care second-generation anti-androgens as novel therapeutic strategies for advanced prostate cancer.
View details for DOI 10.1158/0008-5472.CAN-20-3477
View details for PubMedID 33483372
Engineering Polysaccharide-Based Hydrogel Photonic Constructs: From Multiscale Detection to the Biofabrication of Living Optical Fibers.
Advanced materials (Deerfield Beach, Fla.)
Solid-state optics has been the pillar of modern digital age. Integrating soft hydrogel materials with micro/nanooptics could expand the horizons of photonics for bioengineering. Here, wet-spun multilayer hydrogel fibers are engineered through ionic-crosslinked natural polysaccharides that serve as multifunctional platforms. The resulting flexible hydrogel structure and reversible crosslinking provide tunable design properties such as adjustable refractive index and fusion splicing. Modulation of the optical readout via physical stimuli, including shape, compression, and multiple optical inputs/outputs is demonstrated. The unique permeability of the hydrogels is also combined with plasmonic nanoparticles for molecular detection of SARS-CoV-2 in fiber-coupled biomedical swabs. A tricoaxial 3D printing nozzle is then employed for the continuous fabrication of living optical fibers. Light interaction with living cells enables the quantification and digitalization of complex biological phenomena such as 3D cancer progression and drug susceptibility. These fibers pave the way for advances in biomaterial-based photonics and biosensing platforms.
View details for DOI 10.1002/adma.202105361
View details for PubMedID 34617338
Quantifying the invasion and migration ability of cancer cells with a 3D Matrigel drop invasion assay.
Biology methods & protocols
2021; 6 (1): bpab014
Metastasis is the main cause of cancer-associated morbidity which will account for ∼ 600,000 deaths in the USA in 2021. Defining new mechanisms that drive cancer metastasis is vital for developing new therapeutic strategies and improving clinical outcomes for cancer patients. Herein, we describe a recently established 3D Matrigel drop invasion assay to measure cancer cell invasion and migration capability in vitro. This assay is a versatile and simple tool to test the ability of cells to invade and migrate, test the functional role of genes of interest in cell invasion and migration, analyze the localization of the target proteins at the cell invasion edge in situ, and screen drug effects on cancer cell invasion and migration.
View details for DOI 10.1093/biomethods/bpab014
View details for PubMedID 34377838
View details for PubMedCentralID PMC8346651
MCM2-7 complex is a novel druggable target for neuroendocrine prostate cancer.
2021; 11 (1): 13305
Neuroendocrine prostate cancer (NEPC) is a lethal subtype of prostate cancer that rarely develops de novo in primary tumors and is commonly acquired during the development of treatment resistance. NEPC is characterized by gain of neuroendocrine markers and loss of androgen receptor (AR), making it resistant to current therapeutic strategies targeting the AR signaling axis. Here, we report that MCM2, MCM3, MCM4, and MCM6 (MCM2/3/4/6) are elevated in human NEPC and high levels of MCM2/3/4/6 are associated with liver metastasis and poor survival in prostate cancer patients. MCM2/3/4/6 are four out of six proteins that form a core DNA helicase (MCM2-7) responsible for unwinding DNA forks during DNA replication. Inhibition of MCM2-7 by treatment with ciprofloxacin inhibits NEPC cell proliferation and migration in vitro, significantly delays NEPC tumor xenograft growth, and partially reverses the neuroendocrine phenotype in vivo. Our study reveals the clinical relevance of MCM2/3/4/6 proteins in NEPC and suggests that inhibition of MCM2-7 may represent a new therapeutic strategy for NEPC.
View details for DOI 10.1038/s41598-021-92552-x
View details for PubMedID 34172788
Oncogene-mediated metabolic gene signature predicts breast cancer outcome.
NPJ breast cancer
2021; 7 (1): 141
Breast cancer remains the second most lethal cancer among women in the United States and triple-negative breast cancer is the most aggressive subtype with limited treatment options. Trop2, a cell membrane glycoprotein, is overexpressed in almost all epithelial cancers. In this study, we demonstrate that Trop2 is overexpressed in triple-negative breast cancer (TNBC), and downregulation of Trop2 delays TNBC cell and tumor growth supporting the oncogenic role of Trop2 in breast cancer. Through proteomic profiling, we discovered a metabolic signature comprised of TALDO1, GPI, LDHA, SHMT2, and ADK proteins that were downregulated in Trop2-depleted breast cancer tumors. The identified oncogene-mediated metabolic gene signature is significantly upregulated in TNBC patients across multiple RNA-expression clinical datasets. Our study further reveals that the metabolic gene signature reliably predicts poor survival of breast cancer patients with early stages of the disease. Taken together, our study identified a new five-gene metabolic signature as an accurate predictor of breast cancer outcome.
View details for DOI 10.1038/s41523-021-00341-6
View details for PubMedID 34711841
Ultra-high-frequency radio-frequency acoustic molecular imaging with saline nanodroplets in living subjects.
Molecular imaging is a crucial technique in clinical diagnostics but it relies on radioactive tracers or strong magnetic fields that are unsuitable for many patients, particularly infants and pregnant women. Ultra-high-frequency radio-frequency acoustic (UHF-RF-acoustic) imaging using non-ionizing RF pulses allows deep-tissue imaging with sub-millimetre spatial resolution. However, lack of biocompatible and targetable contrast agents has prevented the successful in vivo application of UHF-RF-acoustic imaging. Here we report our development of targetable nanodroplets for UHF-RF-acoustic molecular imaging of cancers. We synthesize all-liquid nanodroplets containing hypertonic saline that are stable for at least 2 weeks and can produce high-intensity UHF-RF-acoustic signals. Compared with concentration-matched iron oxide nanoparticles, our nanodroplets produce at least 1,600 times higher UHF-RF-acoustic signals at the same imaging depth. We demonstrate in vivo imaging using the targeted nanodroplets in a prostate cancer xenograft mouse model expressing gastrin release protein receptor (GRPR), and show that targeting specificity is increased by more than 2-fold compared with untargeted nanodroplets or prostate cancer cells not expressing this receptor.
View details for DOI 10.1038/s41565-021-00869-5
View details for PubMedID 33782588
The role of Trop2 in prostate cancer: an oncogene, biomarker, and therapeutic target
AMERICAN JOURNAL OF CLINICAL AND EXPERIMENTAL UROLOGY
2021; 9 (1): 73–87
View details for Web of Science ID 000627038200007
- Increasing Diversity in Radiology and Molecular Imaging: Current Challenges Molecular Imaging and Biology 2021
Discovery of CASP8 as a potential biomarker for high-risk prostate cancer through a high-multiplex immunoassay.
2021; 11 (1): 7612
Prostate cancer remains the most common non-cutaneous malignancy among men in the United States. To discover potential serum-based biomarkers for high-risk prostate cancer, we performed a high-multiplex immunoassay utilizing patient-matched pre-operative and post-operative serum samples from ten men with high-grade and high-volume prostate cancer. Our study identified six (CASP8, MSLN, FGFBP1, ICOSLG, TIE2 and S100A4) out of 174 proteins that were significantly decreased after radical prostatectomy. High levels of CASP8 were detected in pre-operative serum samples when compared to post-operative serum samples and serum samples from patients with benign prostate hyperplasia (BPH). By immunohistochemistry, CASP8 protein was expressed at higher levels in prostate cancer tissues compared to non-cancerous and BPH tissues. Likewise, CASP8 mRNA expression was significantly upregulated in prostate cancer when compared to benign prostate tissues in four independent clinical datasets. In addition, mRNA levels of CASP8 were higher in patients with recurrent prostate cancer when compared to patients with non-recurrent prostate cancer and high expression of CASP8 was associated with worse disease-free survival and overall survival in renal cancer. Together, our results suggest that CASP8 may potentially serve as a biomarker for high-risk prostate cancer and possibly renal cancer.
View details for DOI 10.1038/s41598-021-87155-5
View details for PubMedID 33828176
In vivo imaging of methionine aminopeptidase II for prostate cancer risk stratification.
Prostate cancer is one of the most common malignancies worldwide, yet limited tools exist for prognostic risk stratification of the disease. Identification of new biomarkers representing intrinsic features of malignant transformation and development of prognostic imaging technologies are critical for improving treatment decisions and patient survival. In this study, we analyzed radical prostatectomy specimens from 422 patients with localized disease to define the expression pattern of methionine aminopeptidase II (MetAP2), a cytosolic metalloprotease that has been identified as a druggable target in cancer. MetAP2 was highly expressed in 54% of low-grade and 59% of high-grade cancer. Elevated levels of MetAP2 at diagnosis were associated with shorter time to recurrence. Controlled self-assembly of a synthetic small molecule enabled design of the first MetAP2-activated positron emission tomography (PET) imaging tracer for monitoring MetAP2 activity in vivo. The nanoparticles assembled upon MetAP2 activation were imaged in single prostate cancer cells with post-click fluorescent labeling. The fluorine-18 labeled tracers successfully differentiated MetAP2 activity in both MetAP2 knockdown and inhibitor-treated human prostate cancer xenografts by micro-PET/CT scanning. This highly sensitive imaging technology may provide a new tool for non-invasive early risk stratification of prostate cancer and monitoring the therapeutic effect of MetAP2 inhibitors as anti-cancer drugs.
View details for DOI 10.1158/0008-5472.CAN-20-2969
View details for PubMedID 33637565
Plectin is a regulator of prostate cancer growth and metastasis.
Prostate cancer is responsible for over 30,000 US deaths annually, attributed largely to incurable metastatic disease. Here, we demonstrate that high levels of plectin are associated with localized and metastatic human prostate cancer when compared to benign prostate tissues. Knock-down of plectin inhibits prostate cancer cell growth and colony formation in vitro, and growth of prostate cancer xenografts in vivo. Plectin knock-down further impairs aggressive and invasive cellular behavior assessed by migration, invasion, and wound healing in vitro. Consistently, plectin knock-down cells have impaired metastatic colonization to distant sites including liver, lung, kidney, bone, and genitourinary system. Plectin knock-down inhibited number of metastases per organ, as well as decreased overall metastatic burden. To gain insights into the role of plectin in prostate cancer growth and metastasis, we performed proteomic analysis of prostate cancer plectin knock-down xenograft tissues. Gene set enrichment analysis shows an increase in levels of proteins involved with extracellular matrix and laminin interactions, and a decrease in levels of proteins regulating amino acid metabolism, cytoskeletal proteins, and cellular response to stress. Collectively these findings demonstrate that plectin is an important regulator of prostate cancer cell growth and metastasis.
View details for DOI 10.1038/s41388-020-01557-9
View details for PubMedID 33219316
Trop2 is a driver of metastatic prostate cancer with neuroendocrine phenotype via PARP1.
Proceedings of the National Academy of Sciences of the United States of America
Resistance to androgen deprivation therapy, or castration-resistant prostate cancer (CRPC), is often accompanied by metastasis and is currently the ultimate cause of prostate cancer-associated deaths in men. Recently, secondary hormonal therapies have led to an increase of neuroendocrine prostate cancer (NEPC), a highly aggressive variant of CRPC. Here, we identify that high levels of cell surface receptor Trop2 are predictive of recurrence of localized prostate cancer. Moreover, Trop2 is significantly elevated in CRPC and NEPC, drives prostate cancer growth, and induces neuroendocrine phenotype. Overexpression of Trop2 induces tumor growth and metastasis while loss of Trop2 suppresses these abilities in vivo. Trop2-driven NEPC displays a significant up-regulation of PARP1, and PARP inhibitors significantly delay tumor growth and metastatic colonization and reverse neuroendocrine features in Trop2-driven NEPC. Our findings establish Trop2 as a driver and therapeutic target for metastatic prostate cancer with neuroendocrine phenotype and suggest that high Trop2 levels could identify cancers that are sensitive to Trop2-targeting therapies and PARP1 inhibition.
View details for DOI 10.1073/pnas.1905384117
View details for PubMedID 31932422
Discovery of PTN as a serum-based biomarker of pro-metastatic prostate cancer.
British journal of cancer
Distinguishing clinically significant from indolent prostate cancer (PC) is a major clinical challenge. We utilised targeted protein biomarker discovery approach to identify biomarkers specific for pro-metastatic PC. Serum samples from the cancer-free group; Cambridge Prognostic Group 1 (CPG1, low risk); CPG5 (high risk) and metastatic disease were analysed using Olink Proteomics panels. Tissue validation was performed by immunohistochemistry in a radical prostatectomy cohort (n = 234). We discovered that nine proteins (pleiotrophin (PTN), MK, PVRL4, EPHA2, TFPI-2, hK11, SYND1, ANGPT2, and hK14) were elevated in metastatic PC patients when compared to other groups. PTN levels were increased in serum from men with CPG5 compared to benign and CPG1. High tissue PTN level was an independent predictor of biochemical recurrence and metastatic progression in low- and intermediate-grade disease. These findings suggest that PTN may represent a novel biomarker for the presence of poor prognosis local disease with the potential to metastasise warranting further investigation.
View details for DOI 10.1038/s41416-020-01200-0
View details for PubMedID 33288843
Gold Nanoclusters for NIR-II Fluorescence Imaging of Bones.
Small (Weinheim an der Bergstrasse, Germany)
Fluorescence imaging in the second near-infrared window (NIR-II, 1000-1700 nm) holds great promise for deep tissue visualization. Development of novel clinical translatable NIR-II probes is crucial for realizing the medical applications of NIR-II fluorescence imaging. Herein, the glutathione-capped gold nanoclusters (AuNCs, specifically Au25 (SG)18 ) demonstrate highly efficient binding capability to hydroxyapatite in vitro for the first time. Further in vivo NIR-II fluorescence imaging of AuNCs indicate that they accumulate in bone tissues with high contrast and signal-background ratio. AuNCs are also mainly and quickly excreted from body through renal system, showing excellent ribs and thoracic vertebra imaging because of no background signal in liver and spleen. The deep tissue penetration capability and high resolution of AuNCs in NIR-II imaging render their great potential for fluorescence-guided surgery like spinal pedicle screw implantation. Overall, AuNCs are highly promising and clinical translatable NIR-II imaging probe for visualizing bone and bone related abnormalities.
View details for DOI 10.1002/smll.202003851
View details for PubMedID 33000882
Novel Aza-podophyllotoxin derivative induces oxidative phosphorylation and cell death via AMPK activation in triple-negative breast cancer.
British journal of cancer
To circumvent Warburg effect, several clinical trials for different cancers are utilising a combinatorial approach using metabolic reprogramming and chemotherapeutic agents including metformin. The majority of these metabolic interventions work via indirectly activating AMP-activated protein kinase (AMPK) to alter cellular metabolism in favour of oxidative phosphorylation over aerobic glycolysis. The effect of these drugs is dependent on glycaemic and insulin conditions. Therefore, development of small molecules, which can activate AMPK, irrespective of the energy state, may be a better approach for triple-negative breast cancer (TNBC) treatment.Therapeutic effect of SU212 on TNBC cells was examined using in vitro and in vivo models.We developed and characterised the efficacy of novel AMPK activator (SU212) that selectively induces oxidative phosphorylation and decreases glycolysis in TNBC cells, while not affecting these pathways in normal cells. SU212 accomplished this metabolic reprogramming by activating AMPK independent of energy stress and irrespective of the glycaemic/insulin state. This leads to mitotic phase arrest and apoptosis in TNBC cells. In vivo, SU212 inhibits tumour growth, cancer progression and metastasis.SU212 directly activates AMPK in TNBC cells, but does not hamper glucose metabolism in normal cells. Our study provides compelling preclinical data for further development of SU212 for the treatment of TNBC.
View details for DOI 10.1038/s41416-020-01137-4
View details for PubMedID 33139797
- Second-Generation Antiandrogens: From Discovery to Standard of Care in Castration Resistant Prostate Cancer FRONTIERS IN ONCOLOGY 2019; 9
- Loss of Notch1 Activity Inhibits Prostate Cancer Growth and Metastasis and Sensitizes Prostate Cancer Cells to Antiandrogen Therapies MOLECULAR CANCER THERAPEUTICS 2019; 18 (7): 1230–42
- Quantitative Proteomic Profiling Reveals Key Pathways in the Anticancer Action of Methoxychalcone Derivatives in Triple Negative Breast Cancer JOURNAL OF PROTEOME RESEARCH 2018; 17 (10): 3574–85
Defining new drivers of castration- resistant prostate cancer
AMER ASSOC CANCER RESEARCH. 2018: 90
View details for Web of Science ID 000441803800135
Methionine aminopeptidase II (MetAP2) activated in situ self-assembly of small-molecule probes for imaging prostate cancer.
AMER ASSOC CANCER RESEARCH. 2018: 115–16
View details for Web of Science ID 000441803800181
Biomarkers for Diagnosis and Prognosis of Prostate Cancer
View details for DOI 10.5772
- Therapeutic inhibition of Notch1 in metastatic prostate cancer AMER ASSOC CANCER RESEARCH. 2017
The Exosome Total Isolation Chip.
Circulating tumor-derived extracellular vesicles (EVs) have emerged as a promising source for identifying cancer biomarkers for early cancer detection. However, the clinical utility of EVs has thus far been limited by the fact that most EV isolation methods are tedious, nonstandardized, and require bulky instrumentation such as ultracentrifugation (UC). Here, we report a size-based EV isolation tool called ExoTIC (exosome total isolation chip), which is simple, easy-to-use, modular, and facilitates high-yield and high-purity EV isolation from biofluids. ExoTIC achieves an EV yield ∼4-1000-fold higher than that with UC, and EV-derived protein and microRNA levels are well-correlated between the two methods. Moreover, we demonstrate that ExoTIC is a modular platform that can sort a heterogeneous population of cancer cell line EVs based on size. Further, we utilize ExoTIC to isolate EVs from cancer patient clinical samples, including plasma, urine, and lavage, demonstrating the device's broad applicability to cancers and other diseases. Finally, the ability of ExoTIC to efficiently isolate EVs from small sample volumes opens up avenues for preclinical studies in small animal tumor models and for point-of-care EV-based clinical testing from fingerprick quantities (10-100 μL) of blood.
View details for DOI 10.1021/acsnano.7b04878
View details for PubMedID 29090896
Low CD38 Identifies Progenitor-like Inflammation-Associated Luminal Cells that Can Initiate Human Prostate Cancer and Predict Poor Outcome
2016; 17 (10): 2596-2606
Inflammation is a risk factor for prostate cancer, but the mechanisms by which inflammation increases that risk are poorly understood. Here, we demonstrate that low expression of CD38 identifies a progenitor-like subset of luminal cells in the human prostate. CD38(lo) luminal cells are enriched in glands adjacent to inflammatory cells and exhibit epithelial nuclear factor κB (NF-κB) signaling. In response to oncogenic transformation, CD38(lo) luminal cells can initiate human prostate cancer in an in vivo tissue-regeneration assay. Finally, the CD38(lo) luminal phenotype and gene signature are associated with disease progression and poor outcome in prostate cancer. Our results suggest that prostate inflammation expands the pool of progenitor-like target cells susceptible to tumorigenesis.
View details for DOI 10.1016/j.celrep.2016.11.010
View details for Web of Science ID 000390894200010
View details for PubMedID 27926864
v-Src Oncogene Induces Trop2 Proteolytic Activation via Cyclin D1
2016; 76 (22): 6723-6734
Proteomic analysis of castration-resistant prostate cancer demonstrated the enrichment of SRC tyrosine kinase activity in approximately ninety percent of patients. Src is known to induce cyclin D1, and a cyclin D1-regulated gene expression module predict poor outcome in human prostate cancer. The tumor-associated calcium signal transducer 2 [TACSTD2/Trop2/M1S1] is enriched in the prostate, promoting prostate stem cell self-renewal upon proteolytic activation via a γ-secretase cleavage complex (PS1, PS2) and TACE (ADAM17), which releases the Trop2 intracellular domain (Trop2 ICD). Herein, v-Src transformation of primary murine prostate epithelial cells increased the proportion of prostate cancer stem cells as characterized by gene expression, epitope characteristics and prostatosphere formation. Cyclin D1 was induced by v-Src, and Src kinase induction of Trop2 ICD nuclear accumulation, required cyclin D1. Cyclin D1 induced abundance of the Trop2 proteolytic cleavage activation components (PS2, TACE) and restrained expression of the inhibitory component of the Trop2 proteolytic complex (Numb). Prostate cancer patients with increased nuclear Trop2 ICD and cyclin D1, and reduced Numb, had reduced recurrence-free survival probability (hazard ratio 4.35). Cyclin D1 therefore serves as a transducer of v-Src-mediated induction of Trop2 ICD by enhancing abundance of the Trop2 proteolytic activation complex.
View details for DOI 10.1158/0008-5472.CAN-15-3327
View details for Web of Science ID 000388742100029
View details for PubMedID 27634768
Activation of Notch1 synergizes with multiple pathways in promoting castration-resistant prostate cancer
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2016; 113 (42): E6457-E6466
Metastatic castration-resistant prostate cancer (CRPC) is the primary cause of prostate cancer-specific mortality. Defining new mechanisms that can predict recurrence and drive lethal CRPC is critical. Here, we demonstrate that localized high-risk prostate cancer and metastatic CRPC, but not benign prostate tissues or low/intermediate-risk prostate cancer, express high levels of nuclear Notch homolog 1, translocation-associated (Notch1) receptor intracellular domain. Chronic activation of Notch1 synergizes with multiple oncogenic pathways altered in early disease to promote the development of prostate adenocarcinoma. These tumors display features of epithelial-to-mesenchymal transition, a cellular state associated with increased tumor aggressiveness. Consistent with its activation in clinical CRPC, tumors driven by Notch1 intracellular domain in combination with multiple pathways altered in prostate cancer are metastatic and resistant to androgen deprivation. Our study provides functional evidence that the Notch1 signaling axis synergizes with alternative pathways in promoting metastatic CRPC and may represent a new therapeutic target for advanced prostate cancer.
View details for DOI 10.1073/pnas.1614529113
View details for PubMedID 27694579
- Phosphoproteome Integration Reveals Patient-Specific Networks in Prostate Cancer CELL 2016
- N-Myc Drives Neuroendocrine Prostate Cancer Initiated from Human Prostate Epithelial Cells CANCER CELL 2016; 11 (29)
NEW HORIZONS IN INTACT PROTEIN ANALYSIS: OPTIMIZATION OF TOP-DOWN PROTEIN ANALYSIS
CHEMICAL & ENGINEERING NEWS
View details for Web of Science ID 000366244200004
- Notch1 as a key mediator in promoting advanced castration-resistant prostate cancer AMER ASSOC CANCER RESEARCH. 2015
- Multidisciplinary intervention of early, lethal metastatic prostate cancer: Report from the 2015 Coffey-Holden Prostate Cancer Academy Meeting PROSTATE 2015
- Distinct phases of human prostate cancer initiation and progression can be driven by different cell-types CANCER CELL MICROENVIRON 2014
Metastatic castration-resistant prostate cancer reveals intrapatient similarity and interpatient heterogeneity of therapeutic kinase targets
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2013; 110 (49): E4762-E4769
In prostate cancer, multiple metastases from the same patient share similar copy number, mutational status, erythroblast transformation specific (ETS) rearrangements, and methylation patterns supporting their clonal origins. Whether actionable targets such as tyrosine kinases are also similarly expressed and activated in anatomically distinct metastatic lesions of the same patient is not known. We evaluated active kinases using phosphotyrosine peptide enrichment and quantitative mass spectrometry to identify druggable targets in metastatic castration-resistant prostate cancer obtained at rapid autopsy. We identified distinct phosphopeptide patterns in metastatic tissues compared with treatment-naive primary prostate tissue and prostate cancer cell line-derived xenografts. Evaluation of metastatic castration-resistant prostate cancer samples for tyrosine phosphorylation and upstream kinase targets revealed SRC, epidermal growth factor receptor (EGFR), rearranged during transfection (RET), anaplastic lymphoma kinase (ALK), and MAPK1/3 and other activities while exhibiting intrapatient similarity and interpatient heterogeneity. Phosphoproteomic analyses and identification of kinase activation states in metastatic castration-resistant prostate cancer patients have allowed for the prioritization of kinases for further clinical evaluation.
View details for DOI 10.1073/pnas.1319948110
View details for Web of Science ID 000327744900008
View details for PubMedID 24248375
- Identification, characterization and targeting of Docetaxel-resistant prostate cancer cells ASIAN JOURNAL OF ANDROLOGY 2013; 15 (1): 83-84
Prostate cancer originating in basal cells progresses to adenocarcinoma propagated by luminal-like cells
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
View details for DOI 10.1073/pnas.1320565110
Regulated proteolysis of Trop2 drives epithelial hyperplasia and stem cell self-renewal via beta-catenin signaling
GENES & DEVELOPMENT
2012; 26 (20): 2271-2285
The cell surface protein Trop2 is expressed on immature stem/progenitor-like cells and is overexpressed in many epithelial cancers. However the biological function of Trop2 in tissue maintenance and tumorigenesis remains unclear. In this study, we demonstrate that Trop2 is a regulator of self-renewal, proliferation, and transformation. Trop2 controls these processes through a mechanism of regulated intramembrane proteolysis that leads to cleavage of Trop2, creating two products: the extracellular domain and the intracellular domain. The intracellular domain of Trop2 is released from the membrane and accumulates in the nucleus. Heightened expression of the Trop2 intracellular domain promotes stem/progenitor self-renewal through signaling via β-catenin and is sufficient to initiate precursor lesions to prostate cancer in vivo. Importantly, we demonstrate that loss of β-catenin or Trop2 loss-of-function cleavage mutants abrogates Trop2-driven self-renewal and hyperplasia in the prostate. These findings suggest that heightened expression of Trop2 is selected for in epithelial cancers to enhance the stem-like properties of self-renewal and proliferation. Defining the mechanism of Trop2 function in self-renewal and transformation is essential to identify new therapeutic strategies to block Trop2 activation in cancer.
View details for DOI 10.1101/gad.196451.112
View details for Web of Science ID 000309978500004
View details for PubMedID 23070813
Collaboration of Kras and Androgen Receptor Signaling Stimulates EZH2 Expression and Tumor-Propagating Cells in Prostate Cancer
2012; 72 (18): 4672-4681
Elevation of the chromatin repression factor enhancer of zeste homolog (EZH2) is associated with progression and poor prognosis in several human cancers including prostate cancer. However, the mechanisms driving EZH2 expression are not fully understood. In this study, we investigated the functional synergy in prostate cancers in mice resulting from activation of the androgen receptor, Kras, and Akt, which drives three of the most frequently activated oncogenic signaling pathways in prostate cancer. Although, any two of these three events were sufficient to promote the formation and progression of prostate cancer, only the synergy of androgen receptor and Kras signaling could elevate EZH2 expression and expand prostate cancer progenitor cells in vivo. Our findings have revealed a genetic mechanism resulting in enhanced EZH2 expression during the progression of aggressive prostate cancer, with important implications for understanding how to target advanced disease where cancer progenitor cells may be critical.
View details for DOI 10.1158/0008-5472.CAN-12-0228
View details for Web of Science ID 000309507900009
View details for PubMedID 22805308
Oncogene-specific activation of tyrosine kinase networks during prostate cancer progression
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2012; 109 (5): 1643-1648
Dominant mutations or DNA amplification of tyrosine kinases are rare among the oncogenic alterations implicated in prostate cancer. We demonstrate that castration-resistant prostate cancer (CRPC) in men exhibits increased tyrosine phosphorylation, raising the question of whether enhanced tyrosine kinase activity is observed in prostate cancer in the absence of specific tyrosine kinase mutation or DNA amplification. We generated a mouse model of prostate cancer progression using commonly perturbed non-tyrosine kinase oncogenes and pathways and detected a significant up-regulation of tyrosine phosphorylation at the carcinoma stage. Phosphotyrosine peptide enrichment and quantitative mass spectrometry identified oncogene-specific tyrosine kinase signatures, including activation of EGFR, ephrin type-A receptor 2 (EPHA2), and JAK2. Kinase:substrate relationship analysis of the phosphopeptides also revealed ABL1 and SRC tyrosine kinase activation. The observation of elevated tyrosine kinase signaling in advanced prostate cancer and identification of specific tyrosine kinase pathways from genetically defined tumor models point to unique therapeutic approaches using tyrosine kinase inhibitors for advanced prostate cancer.
View details for DOI 10.1073/pnas.1120985109
View details for Web of Science ID 000299731400061
View details for PubMedID 22307624
p21 Cooperates with DDB2 Protein in Suppression of Ultraviolet Ray-induced Skin Malignancies
JOURNAL OF BIOLOGICAL CHEMISTRY
2012; 287 (5): 3019-3028
Exposure to ultraviolet rays (UV) in sunlight is the main cause of skin cancer. Here, we show that the p53-induced genes DDB2 and p21 are down-regulated in skin cancer, and in the mouse model they functionally cooperate to prevent UV-induced skin cancer. Our previous studies demonstrated an antagonistic role of DDB2 and p21 in nucleotide excision repair and apoptosis. Surprisingly, we find that the loss of p21 restores nucleotide excision repair and apoptosis in Ddb2(-/-) mice, but it does not protect from UV-mediated skin carcinogenesis. In contrast, Ddb2(-/-)p21(-/-) mice are significantly more susceptible to UV-induced skin cancer than the Ddb2(-/-) or the p21(-/-) mice. We provide evidence that p21 deletion in the Ddb2(-/-) background causes a strong increase in cell proliferation. The increased proliferation in the Ddb2(-/-)p21(-/-) background is related to a severe deficiency in UV-induced premature senescence. Also, the oncogenic pro-proliferation transcription factor FOXM1 is overexpressed in the p21(-/-) background. Our results show that the anti-proliferative and the pro-senescence pathways of DDB2 and p21 are critical protection mechanisms against skin malignancies.
View details for DOI 10.1074/jbc.M111.295816
View details for Web of Science ID 000300295100009
View details for PubMedID 22167187
Cul4A is essential for spermatogenesis and male fertility
2011; 352 (2): 278-287
The mammalian Cul4 genes, Cul4A and Cul4B, encode the scaffold components of the cullin-based E3 ubiquitin ligases. The two Cul4 genes are functionally redundant. Recent study indicated that mice expressing a truncated CUL4A that fails to interact with its functional partner ROC1 exhibit no developmental phenotype. We generated a Cul4A-/- strain lacking exons 4-8 that does not express any detectable truncated protein. In this strain, the male mice are infertile and exhibit severe deficiencies in spermatogenesis. The primary spermatocytes are deficient in progression through late prophase I, a time point when expression of the X-linked Cul4B gene is silenced due to meiotic sex chromosome inactivation. Testes of the Cul4A-/- mice exhibit extensive apoptosis. Interestingly, the pachytene spermatocytes exhibit persistent double stranded breaks, suggesting a deficiency in homologous recombination. Also, we find that CUL4A localizes to the double stranded breaks generated in pre-pachytene spermatocytes. The observations identify a novel function of CUL4A in meiotic recombination and demonstrate an essential role of CUL4A in spermatogenesis.
View details for DOI 10.1016/j.ydbio.2011.01.028
View details for Web of Science ID 000289180200009
View details for PubMedID 21291880
- SU086, a New Inhibitor of HSP90, Impairs Glycolysis and Represents a New Treatment Strategy for Advanced Prostate Cancer 2011
Primitive origins of prostate cancer: In vivo evidence for prostate-regenerating cells and prostate cancer-initiating cells
2010; 4 (5): 385-396
Tissue stem cells have been linked to cancers of epithelial origin including the prostate. There are three relevant issues concerning stem cells and cancer that rely solely on functional studies: 1. Are there tissue-regenerating stem cells in the adult organ? 2. Can tissue-regenerating cells serve as targets for transformation? 3. Do primary tumors contain tumor-propagating (cancer stem) cells? We will review the recent literature with respect to these critical issues to provide a direct link between primitive cells and prostate cancer.
View details for DOI 10.1016/j.molonc.2010.06.009
View details for Web of Science ID 000282566200003
View details for PubMedID 20688584
DDB2 (Damaged-DNA binding protein 2) in nucleotide excision repair and DNA damage response
2009; 8 (24): 4067-4071
DDB2 was identified as a protein involved in the Nucleotide Excision Repair (NER), a major DNA repair mechanism that repairs UV damage to prevent accumulation of mutations and tumorigenesis. However, recent studies indicated additional functions of DDB2 in the DNA damage response pathway. Herein, we discuss the proposed mechanisms by which DDB2 activates NER and programmed cell death upon DNA damage through its E3 ligase activity.
View details for Web of Science ID 000273232300023
View details for PubMedID 19923893
Proliferation defects and genome instability in cells lacking Cul4A
2009; 28 (26): 2456-2465
The Cul4A gene, which encodes a core component of a cullin-based E3 ubiquitin ligase complex, is overexpressed in breast and hepatocellular cancers. In breast cancers, overexpression of Cul4A strongly correlates with poor prognosis. In addition, Cul4A is required for early embryonic development. The early lethality of mouse embryos prevented a detailed analysis of the functions of Cul4A. Here, we used a strain of mice carrying floxed alleles of Cul4A to study its role in cell division, in vitro and in vivo. Embryonic fibroblasts (MEFs) show a severe deficiency in cell proliferation after deletion of Cul4A. We observed that the Cul4A protein is abundantly expressed in the brain, liver and the mammary tissue of pregnant mice. Deletion of Cul4A in the liver impairs hepatocyte proliferation during regeneration after carbon tetrachloride (CCl(4))-induced injury. The Cul4A-deleted cells are slow in entering the S phase, and are deficient in progressing through the early M phase. Several cell-cycle regulators, including p53 and p27Kip1, are deregulated in the Cul4A-deleted cells. Expression of a dominant negative mutant of p53 causes significant reversal of the proliferation defects in Cul4A-deleted cells. The Cul4A-deleted cells show an aberrant number of centrosome, multipolar spindles and micronuclei formation. Furthermore, those cells are sensitive to UV irradiation and show reduced levels of unscheduled DNA synthesis (UDS). Together, our observations indicate that Cul4A is required for efficient cell proliferation, control of centrosome amplification and genome stability.
View details for DOI 10.1038/onc.2009.86
View details for Web of Science ID 000267601400004
View details for PubMedID 19430492
DDB2 decides cell fate following DNA damage
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2009; 106 (26): 10690-10695
The xeroderma pigmentosum complementation group E (XP-E) gene product damaged-DNA binding protein 2 (DDB2) plays important roles in nucleotide excision repair (NER). Previously, we showed that DDB2 participates in NER by regulating the level of p21(Waf1/Cip1). Here we show that the p21(Waf1/Cip1) -regulatory function of DDB2 plays a central role in defining the response (apoptosis or arrest) to DNA damage. The DDB2-deficient cells are resistant to apoptosis in response to a variety of DNA-damaging agents, despite activation of p53 and the pro-apoptotic genes. Instead, these cells undergo cell cycle arrest. Also, the DDB2-deficient cells are resistant to E2F1-induced apoptosis. The resistance to apoptosis of the DDB2-deficient cells is caused by an increased accumulation of p21(Waf1/Cip1) after DNA damage. We provide evidence that DDB2 targets p21(Waf1/Cip1) for proteolysis. The resistance to apoptosis in DDB2-deficient cells also involves Mdm2 in a manner that is distinct from the p53-regulatory activity of Mdm2. Our results provide evidence for a new regulatory loop involving the NER protein DDB2, Mdm2, and p21(Waf1/Cip1) that is critical in deciding cell fate (apoptosis or arrest) upon DNA damage.
View details for DOI 10.1073/pnas.0812254106
View details for Web of Science ID 000267564300055
View details for PubMedID 19541625
The xeroderma pigmentosum group E gene product DDB2 activates nucleotide excision repair by regulating the level of p21(Waf1/Cip1)
MOLECULAR AND CELLULAR BIOLOGY
2008; 28 (1): 177-187
The xeroderma pigmentosum group E gene product DDB2, a protein involved in nucleotide excision repair (NER), associates with the E3 ubiquitin ligase complex Cul4A-DDB1. But the precise role of these interactions in the NER activity of DDB2 is unclear. Several models, including DDB2-mediated ubiquitination of histones in UV-irradiated cells, have been proposed. But those models lack clear genetic evidence. Here we show that DDB2 participates in NER by regulating the cellular levels of p21(Waf1/Cip1). We show that DDB2 enhances nuclear accumulation of DDB1, which binds to a modified form of p53 containing phosphorylation at Ser18 (p53(S18P)) and targets it for degradation in low-dose-UV-irradiated cells. DDB2(-/-) mouse embryonic fibroblasts (MEFs), unlike wild-type MEFs, are deficient in the proteolysis of p53(S18P). Accumulation of p53(S18P) in DDB2(-/-) MEFs causes higher expression p21(Waf1/Cip1). We show that the increased expression of p21(Waf1/Cip1) is the cause NER deficiency in DDB2(-/-) cells because deletion or knockdown of p21(Waf1/Cip1) reverses their NER-deficient phenotype. p21(Waf1/Cip1) was shown to bind PCNA, which is required for both DNA replication and NER. Moreover, an increased level of p21(Waf1/Cip1) was shown to inhibit NER both in vitro and in vivo. Our results provide genetic evidence linking the regulation of p21(Waf1/Cip1) to the NER activity of DDB2.
View details for Web of Science ID 000251925300015
View details for PubMedID 17967871