Abstract A32: Screening for synthetic lethal interactions using customized epigenetic CRISPR-Cas9 libraries

Abstract

Abstract Identification of synthetic lethal (SNL) interactions provides a framework for exploring novel treatment options to cancer based on biomarker analysis. Recent research in this field has been powered up by the latest CRISPR-Cas9 gene editing technology, which allows for single gene manipulation or genome-scale knockout/activation screens. Typically, any non-essential gene can be inactivated in a cell line to generate an isogenic mutant cell line, and single-guide RNA (sgRNA) sequences against any list of genes of interest can be constructed to lentiviral Cas9 vectors to interrogate the isogenic cell lines for SNL interactions. Here we demonstrated two alternative types of SNL screens using customized epigenetic CRISPR-Cas9 libraries. In one screen, we built two sgRNA libraries targeting the N terminus or functional domains of 710 human epigenetic regulators. The libraries were infected to a pomalidomide-resistant multiple myeloma (MM) cell line, which was then followed by pomalidomide treatment. Deep sequencing of the sgRNAs from these cells identified potential targets which when inactivated would re-sensitize the cells to pomalidomide. In the other screen, we built a sgRNA library targeting the functional domains of 116 mouse methyltransferases and demethylases, which was infected to a mouse melanoma cell line Cloudman S91. Syngeneic mouse tumor model derived from the infected cells was treated with anti-mPD-1 monoclonal antibody. Deep sequencing of the tumors would identify potential druggable targets to sensitize or antagonize the tumors to anti-PD-1 immunotherapy. In summary, SNL screens combining CRISPR-Cas9 library with targeted therapeutics or with single gene editing in isogenic cell lines can enable discovery of novel targets for precision cancer treatment. Citation Format: Wenrong Zhou, Min Long, Xi Li, Zhengang Peng, Qunsheng Ji, Yong Cang. Screening for synthetic lethal interactions using customized epigenetic CRISPR-Cas9 libraries [abstract]. In: Proceedings of the AACR Precision Medicine Series: Opportunities and Challenges of Exploiting Synthetic Lethality in Cancer; Jan 4-7, 2017; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2017;16(10 Suppl):Abstract nr A32.