Abstract 5522: Cell state modulates the KRASG12C proximal proteome

Abstract Background: KRAS mutations occur in ∼25% of lung adenocarcinomas (LUAD), with KRASG12C being the most common. There has been limited clinical success with KRAS inhibitors due intrinsic/acquired resistance. EMT is a known mechanism by which cancer cells become resistant to targeted therapy. Here, we aim to map protein interactors of KRASG12C in lung cancer cells using proximity-dependent biotin labeling (BioID) to gain insights into key regulators/effectors of oncogenic signaling and therapy resistance. Methods: Dox-inducible fusion of KRASG12C with the BirA biotin ligase was expressed in H358 LUAD cells. To determine alterations in KRASG12C interactome induced by EMT, BioID/mass spectrometry was performed on BirA-KRASG12C expressing cells, with or without chronic TGF-β treatment (to induce EMT). Transduced H358 cells treated either with Biotin or Dox alone were used as controls for the BioID experiment. Results: BioID analysis identified 144 proteins as potential proximal interactors for KRASG12C, which include known effectors of RAS signaling, such as NF1, RAF1, RASA1, MTOR, as well as novel ones, such as KEAP1, ASAP1, CRIP2, CRK, GULP1, AFDN. Pathway analysis suggests that these proximal proteins are involved in regulation of actin cytoskeleton, RAP1, PI3K-Akt, focal adhesion, and Ras signaling pathways. Our data also shows that TGF-β induced EMT reduces KRASG12C’s interaction with several of these known effectors, such as MTOR, RICTOR, and RAF1, while gaining new interactors, such as SPRED2, NOTCH2, DEPC1B and F11R. We also observe a reduction in RAS activity, RAS-RAF proximity and pERK/pRSK in TGF-β induced cells compared to parental cells. Conclusions: We show that BioID system can identify KRASG12C interactome proteins in a cell line model of LUAD. Our data suggests that upon undergoing TGF-β induced EMT, the KRASG12C interactome in these cells alter and now couple less with RAS/MTOR signaling effectors. We also observe similar change in sotorasib-resistant H358 cells showing EMT features, where KRASi no longer suppresses ERK signaling. These studies can understand variations in KRASG12C interactome under epithelial vs mesenchymal state and potentially identify new therapeutic vulnerabilities for cells that have undergone EMT. Citation Format: Anurima Majumder, Liznair Bridenstine, Denis Imbody, Kiah Bowers, Dalia Ercan, Bin Fang, Eric Haura. Cell state modulates the KRASG12C proximal proteome [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5522.