Abstract
Background: Mutations in DNA Damage Response (DDR) genes, including those resulting in loss of Ataxia-Telangiectasia, Mutated (ATM) expression are common in advanced prostate cancers (PC). Poly (ADP-ribose) polymerase (PARP) inhibitors are approved in this setting but demonstrate limited clinical efficacy in ATM-mutant PCs. In this project, we sought to define the impact of ATM loss on DDR pathways in PC, with the goal of identifying alternate therapeutic vulnerabilities. Methods: ATM-KO PC cell lines were generated via CRISPR-Cas9. ATM loss and attenuation of downstream kinase activity were confirmed via western blot. Phosphoproteomic evaluation in parental and ATM-KO cells was performed following ionizing radiation (IR). Clonogenic survival assays were performed after treatment with inhibitors and/or IR. Kinetics of DDR foci recruitment and resolution were interrogated with immunofluorescence (IF). DNA fiber assays were utilized to assess replication stress. Results: ATM-KO PC cells were able to effectively repair DNA damage following IR, as measured by resolution of yH2ax, 53BP1, and MDC1 foci. Phosphoproteomic studies indicated that ATM-KO cells maintained canonical DDR pathways through activation of ATR and DNA-PKcs kinases. Treatment of ATM-KO cells with either the ATR inhibitor VX970 or the DNA-PKcs inhibitor M3814 incrementally affected DDR in ATM-KO cells compared to ATM-proficient parental control cells. Importantly, combination treatment with VX970 and M3814 was needed to prevent downstream DDR foci recruitment in ATM-KO cells and was more effective in radiosensitizing ATM-KO PC than either parental control cells or single drug treatment. These data indicate that the activity of any one of the trinities of these kinases is sufficient to mediate DDR and that blockade of both ATR and DNA-PKcs is needed to effectively prevent DDR in ATM-KO PC. Further, DNA fiber assays showed significantly decreased fork length with dual treatment compared to control or single drug, indicating increased replication stress. We then leveraged a RUVBL1 ATPase inhibitor Compound B, which affects the expression of these three kinases. In ATM-KO PC cells, Compound B attenuated ATR and DNA-PKcs expression and radiosensitized the cells as shown by clonogenic survival assays. DNA fiber assays indicated that Compound B induced replication stress in ATM-KO PC cells to the same extent as combination therapy. In combination with IR, Compound B also significantly attenuated the growth of ATM-KO PC xenografts in vivo. Conclusions: Our unbiased phosphoproteomic approach indicated that ATR and DNA-PKCs mediate DDR following IR in ATM-KO PC cells, and that dual targeting of both ATR and DNA-PKcs is necessary to block DDR in ATM-KO PC cells. We have identified that Compound B effectively depletes ATR and DNA-PKcs, sensitizes to DNA damage, and induces replication stress in ATM-KO PCs. Our studies suggest that Compound B may be a novel therapeutic strategy in ATM-mutant PC.
Citation Format: Mia E. Hofstad, Lan Yu, Andrea Woods, Zoi E. Sychev, Alice Mazzagatti, Xiaofang Huo, Ralf Kittler, Peter Ly, Justin M. Drake, Ganesh V. Raj. Deciphering DNA damage repair in ATM mutant prostate cancers [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: DNA Damage Repair: From Basic Science to Future Clinical Application; 2024 Jan 9-11; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2024;84(1 Suppl):Abstract nr A020.
Need a simple solution for managing your BibTeX entries? Explore CiteDrive!
- Web-based, modern reference management
- Collaborate and share with fellow researchers
- Integration with Overleaf
- Comprehensive BibTeX/BibLaTeX support
- Save articles and websites directly from your browser
- Search for new articles from a database of tens of millions of references
Try out CiteDrive More from our Archive
-
DOI: 10.1158/1940-6207.capr-23-0359 2024
Acceptability of Personalized Lung Cancer Screening Program Among Primary Care Providers
Paul J. Resong, Jiangong Niu, Gabrielle F. Duhon, Lewis E. Foxhall, Sanjay Shete, Robert J. Volk, Iakovos Toumazis
-
DOI: 10.1146/annurev-cancerbio-061421-014236 2024
Next-Generation Therapies for Multiple Myeloma
Erin W. Meermeier, P. Leif Bergsagel, Marta Chesi
-
DOI: 10.1146/annurev-cancerbio-062822-110356 2024
Therapeutic Discovery for Chromatin Complexes: Where Do We Stand?
Dominic D.G. Owens, Matthew E.R. Maitland, Cheryl H. Arrowsmith, Dalia Barsyte-Lovejoy
-
DOI: 10.1146/annurev-cancerbio-062722-012209 2024
Small-Molecule Approaches to Target Transcription Factors
Huarui Cui, Morgan Stilgenbauer, Angela N. Koehler
-
DOI: 10.1200/jco.23.01796 2024
Improved Cardiomyopathy Risk Prediction Using Global Longitudinal Strain and N-Terminal-Pro-B-Type Natriuretic Peptide in Survivors of Childhood Cancer Exposed to Cardiotoxic Therapy
Matthew J. Ehrhardt, Qi Liu, Daniel A. Mulrooney, Isaac B. Rhea, Stephanie B. Dixon, John T. Lucas, Yadav Sapkota, Kyla Shelton, Kirsten K. Ness, Deo Kumar Srivastava, Aaron McDonald, Leslie L. Robison, Melissa M. Hudson, Yutaka Yasui, Gregory T. Armstrong
-
DOI: 10.1200/po.23.00257 2024
Use of Neoadjuvant Vandetanib in Aggressive Pediatric Medullary Thyroid Carcinoma
Ronik Kothari, Sara Kreimer, Helen Nadel, Hilary Seeley, Gary Hartman, Kara D. Meister
-
DOI: 10.1200/po.23.00296 2024
Validity and Efficiency of Progression-Free Survival-2 as a Surrogate End Point for Overall Survival in Advanced Cancer Randomized Trials
Rachel Woodford, Deborah Zhou, Peey-Sei Kok, Sally J. Lord, Michael Friedlander, Ian Marschner, R. John Simes, Chee Khoon Lee
-
DOI: 10.1200/po.23.00333 2024
Somatic Versus Germline: A Case Series of Three Children With <i>ATM</i>-Mutated Medulloblastoma
Lydia T. Tam, Bonnie Cole, Shannon M. Stasi, Vera A. Paulson, Jason N. Wright, Corrine Hoeppner, Susan Holtzclaw, Erin E. Crotty, Richard G. Ellenbogen, Amy Lee, Ralph P. Ermoian, Christina M. Lockwood, Sarah E.S. Leary, Rebecca Ronsley
-
DOI: 10.1200/po.23.00117 2024
Precision Medicine for Childhood Cancer: Current Limitations and Future Perspectives
Martin G. McCabe, Birgit Geoerger, Louis Chesler, Darren Hargrave, D. Williams Parsons, Cornelis M. van Tilburg, Gudrun Schleiermacher, John A. Hickman, Sally L. George
-
DOI: 10.1200/po.23.00196 2024
Modifiable Risk Factors and Risk of Colorectal and Endometrial Cancers in Lynch Syndrome: A Systematic Review and Meta-Analysis
Robert F. Power, Damien E. Doherty, Imelda Parker, David J. Gallagher, Maeve A. Lowery, Karen A. Cadoo