Abstract 937: Dissection of KRAS-driven survival signaling networks via phosphoproteomics in lung cancer cells.

Abstract

Abstract KRAS mutation accounts for development of approximately 30% of lung adenocarcinoma yet therapeutic options remain limited. We report our efforts to explore downstream signaling proteins driven by KRAS, including TANK-binding kinase 1 (TBK1), through a mass spectrometry based phosphoproteomics approach. We hypothesized that such a search would identify key survival proteins as well as uncover potential adaptive resistance mechanisms. We identified proteins whose phosphorylation is regulated TBK1 using SILAC and mass spectrometry following RNAi-mediated TBK1 knockdown. A cohesive network view of the underlying results centered major effects on Polo-like Kinase 1 (PLK1) and decreased phosphorylation of its targets implicating TBK1 as involved in mitosis. TBK1 activity was induced especially in late G1 and M phase, and loss of TBK1 sensitized lung cancer cells to a mitotic stressor. Surprisingly, we found that TBK1 knockdown increased phosphorylation of oncogenic kinases, including EGFR, Met, and ERK1/2. We screened multiple tyrosine kinase inhibitors in combination with TBK1 loss and found the pro-apoptotic effect of TBK1 loss was enhanced by dasatinib, a Src-family kinase inhibitor, providing a mechanistic basis for rational combinatorial therapies involving TBK1. Moving upstream, we analyzed global phosphoproteome change after KRAS knockdown and identified unexpected role of KRAS involved in CDK1 regulation as well as potential adaptive resistant mechanisms that can protect cells against KRAS loss. Finally, we have started exploring changes in the programmed kinome in KRAS mutated lung cancer cells following exposure to MEK inhibitors using activity based protein profiling. Initial experiments have characterized phenotypic effects of two MEK inhibitors in a subset of KRAS mutated lung cancer cells and preliminary studies have identified increased levels of some kinases following MEK inhibition. Collectively, we expect this kinome and phosphoproteomic network based approach will provide better insights into survival signaling mechanism maintaining survival of KRAS mutant lung cancer cell as well as novel therapeutic strategies for this cancer subtype. Updated work will be presented. Supported by the SPORE in Lung Cancer (P50-CA119997) Citation Format: Jae-Young Kim, Eric A. Welsh, Bin Fang, Umut Oguz, Jiannong Li, Fumi Kinose, Crystina Bronk, Amer A. Beg, Ann Chen, Steven Eschrich, John Koomen, Eric B. Haura. Dissection of KRAS-driven survival signaling networks via phosphoproteomics in lung cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 937. doi:10.1158/1538-7445.AM2013-937