Abstract A63: Whole-genome CRISPR/CAS9 screen using patient samples reveals JunB as a unique genetic liability

Abstract

Abstract Background: Epithelial ovarian cancers are the fifth leading cause of cancer-related deaths in American women, with a five-year overall survival rate for patients diagnosed at advanced stages of less than 30%. High-grade serous ovarian cancers (HGSOCs), the most common histologic subtype, often initially responds to platinum-based chemotherapy. However, over 80% of patients experience chemoresistant recurrence in advanced-stage disease. Methods: We have established over 40 patient-derived HGSOC cell lines from ascites of patients with recurrences and hypothesized that these refractory HGSOC cell lines may each possess genetic liabilities and be dependent on unique pathways for survival that can be identified using an unbiased screening approach for the development of personalized therapies. In one such example, we identified candidate genes that are uniquely essential to a single HGSOC patient (ptD), as proof of concept, using a genome-wide lentiviral sgRNA library, containing 187,536 sgRNAs targeting 18,543 protein-coding human genes and 1,504 nontargeting control sgRNAs in a Cas9-containing vector. Results: The unbiased CRISPR screen identified BRAF (p=2E-6) as a specific susceptibility of ptD, confirming the known oncogene addiction of this primary cell line carrying a V600E mutation, as well as a significant sensitivity to JUNB deletion (p=6E-6). Knockout of the JUNB gene, using lentiviruses expressing guide RNAs and Cas9 protein targeted to JUNB, repressed cell proliferation in vitro in ptD cells but not other primary cell lines. Moreover, in a xenograft mouse model, JUNB KO ptD cells displayed slower tumor growth than control JUNB WT cells. Conclusion: We have confirmed in a single patient cell line our ability to identify and validate unique genetic liabilities, suggesting the approach can be scaled to rapidly screen primary HGSOC samples for personalized therapy. Citation Format: Nobuhiro Takahashi, Heather Keys, Raghav Mohan, Lihua Zhang, Yi Li, Hatice D. Saatcioglu, Nicholas Nagykery, Patricia K. Donahoe, David Sabatini, David Pépin. Whole-genome CRISPR/CAS9 screen using patient samples reveals JunB as a unique genetic liability [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research; 2019 Sep 13-16, 2019; Atlanta, GA. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(13_Suppl):Abstract nr A63.