Abstract 1663: Single-cell signaling analysis reveals that major vault protein facilitates RasG12C inhibitor resistance

Abstract Covalent inhibitors of RasG12C are the first clinically-approved drugs for targeting mutant Ras-driven cancers. However, the rapid development of clinical resistance to current Ras G12C inhibitors is common. It has been demonstrated that a subpopulation of cancer cells facilitate drug resistance but the mechanistic basis of this heterogenous response is not well understood. Here, we utilized recently developed Ras sensors to profile the environment of active Ras and to measure the activity of endogenous Ras to pair structure (Ras signalosome) to function (Ras activity), respectively, at a single-cell level. With this approach, we found that a subpopulation of KRasG12C cells treated with RasG12C-GDP inhibitors underwent oncogenic signaling and metabolic changes driven by WT Ras at the golgi and mutant Ras at mitochondria, respectively. Our Ras sensors identified Major Vault Protein (MVP) as a mediator of Ras activation at both subcellular locations by scaffolding Ras signaling pathway components and metabolite channels. We found that recently developed RasG12C-GTP inhibitors also led to MVP-mediated WT Ras signaling at the golgi, demonstrating that this a general mechanism of RasG12C inhibitor resistance. Overall, single-cell analyses enabled the discovery of a RasG12C inhibitor-resistant subpopulation driven by MVP, providing insight into the complex and heterogenous rewiring that confers drug resistance in cancer. Citation Format: Jason Z. Zhang, Shao-En Ong, David Baker, Dustin J. Maly. Single-cell signaling analysis reveals that major vault protein facilitates RasG12C inhibitor resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1663.