LAUSR

The RAS family genes encode small GTP-binding cytoplasmic proteins that are important signaling molecules. They regulate cell growth, survival and differentiation by coupling receptor activation to downstream effector pathways. Activating mutations of oncogenic RAS pathway genes are frequently detected in human cancers. KRAS is the most frequently mutated oncogene in human cancers. Most of these tumors are addicted to KRAS signaling. However, tumors can become resistant to RAS signaling pathway inhibitors through the activation of suppressor mechanisms. A possible explanation is that these tumors carry a second genomic perturbation that can compensate for the detrimental effects of the RAS signaling inhibitors, a phenomenon referred to as suppression. In model organisms, suppression interactions are generally divided into two classes: genomic suppressors which are secondary mutations in the genome that bypass a mutant phenotype, and dosage suppression interactions in which overexpression of a suppressor gene rescues a mutant phenotype. We decided to use the latter strategy in human cancer cells to identify KRAS suppressor genes. KRAS suppressor genes can be involved in resistance mechanisms of RAS pathway inhibitors and this approach could identify new targets for drug research programs and/or novel drug combinations. In this study we performed a screen on a human Open Reading Frame library (hORFeome collection) to identify potential KRAS suppressor genes. First, we engineered a SW620 cell line with a conditional expression of KRAS G12V by replacing the KRAS endogenous promoter by the doxycycline regulated TREG3 promoter. Second, we transduced this conditional cell line with a human ORFeome collection, and we looked for suppressors among the transduced cells that lead to cell proliferation in absence of KRAS G12V protein. Then candidate suppressors have been identified by NGS and validated after individual cloning and expression in SW620 KRAS conditional cells. Finally, two transcription factors and two orphan G protein-coupled receptors have been validated as KRAS suppressor genes when they are highly expressed. Citation Format: Christophe Marcireau, Philippine Furge, Fanny Sennechael, Alice Willart, Anne-Marie Blanchet, Veeranagouda Yaligara, Michel Didier, Frederic Lacroix, Melina Meunier, Laurent Debussches. Identification of KRAS suppressor genes: an ORFeome library screening [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2623.