Abstract B09: Combining proteomics and genetic screens to identify KRAS synthetic lethal interactions

Abstract

Abstract KRAS is a member of the RAS superfamily of small GTPases, proteins that act as molecular switches regulating cellular pathways such as growth, survival, and membrane trafficking. Activating point mutations in KRAS are found in approximately 15% of all cancers and contribute to a malignant phenotype through deregulation of normal cell proliferation. Despite discovering RAS mutations in cancer over three decades ago and strong evidence that RAS mutations drive cancer progression and response to therapy, there have been limited advances in targeting RAS directly. In lieu of direct inhibitors, identifying synthetic lethal (SL) partners with mutant KRAS would reveal putative drug targets. This strategy has been employed previously but with limited success. We hypothesize that using tools such as novel conditional mutant KRAS isogenic cell lines and CRISPR-based loss-of-function screening will uncover pathways whose depletion selectively impairs mutant KRAS cells. Additionally, approaching this from a multi-omics angle, where we combine proteomics and CRISPR screening, will allow us to prioritize targets from each screen. We used CRISPR/Cas9-mediated genome engineering to generate a KRAS WT colon cancer cell line with conditional expression of mutant KRAS. Characterization of our isogenic cell lines confirms that KRAS G12D expression upregulates KRAS activity and enhances tumorigenicity. We used a CRISPR library targeting druggable genes and screened these isogenic cells in vitro, and additionally performed mass spectrometry on the isogenic pair to look at the differential regulation of proteins and phospho-proteins upon KRAS G12D expression. We plan to determine if the overlap of these datasets can provide us with a prioritized list of hits to validate, arguing for a multi-omics approach to better understand synthetic lethal interactions. Citation Format: Shikha S. Sheth, Danielle R. Cook, Samantha D. Strasser, Timothy D. Martin, Sneha Menon, Olesja Popow, Joao A. Paulo, Steve J. Elledge, Kevin M. Haigis. Combining proteomics and genetic screens to identify KRAS synthetic lethal interactions [abstract]. In: Proceedings of the AACR Special Conference on Targeting RAS-Driven Cancers; 2018 Dec 9-12; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(5_Suppl):Abstract nr B09.