Abstract 968: β-catenin plays an important role in lung tumor development induced by EGFR mutations

Abstract

Abstract The discovery of somatic mutations in epidermal growth factor receptor (EGFR) and the development of EGFR tyrosine kinase inhibitors (TKIs), such as gefitinib and erlotinib, have revolutionized treatment for non-small cell lung cancer (NSCLC). Resistance to TKIs emerges in almost all patients, but currently no effective treatment is available.Therefore, novel strategies to either prevent or overcome resistance are sorely needed. Here we show that β-catenin is essential for development of EGFR mutated lung cancers. We found that β-catenin was upregulated, translocated to the nucleus, and subsequently activated in both EGFR mutated lung cancer cell lines and EGFR mutation driven lung tumors. We demonstrated that mutant EGFR preferentially bound to β-catenin and caused tyrosine-phosphorylation of β-catenin. Tyrosine-phosphorylation of β-catenin led to stabilization, nuclear translocation, and transcriptional activity particularly in cells harboring EGFR-L858R (LR)-T790M (TM). Pharmacological β-catenin inhibition using ICG-001, which specifically blocks the CBP-β-catenin interaction, suppressed growth of both H1975 cells harboring EGFR-LR-TM and lung tumors in EGFR-LR-TM transgenic mice. To further examine whether β-catenin plays an important role in lung tumorigenesis, we generated an EGFR-LR-TM lung cancer mouse model in which the β-catenin gene (Ctnnb1) can be conditionally deleted. Genetic deletion of Ctnnb1 dramatically reduced lung tumor formation and showed significantly longer survival. Taken together, our data suggest that β-catenin plays an important role in mutant EGFR-driven lung tumorigenesis and that targeting the β-catenin pathway may provide novel strategies to prevent lung cancer development and/or overcome resistance to EGFR TKIs. Citation Format: Sohei Nakayama, Natasha J. Sng, Julian Carretero, Robert Welner, Yuichiro Hayashi, Mihoko Yamamoto, Tan J. Alistair, Norihiro Yamaguchi, Hiroyuki Yasuda, Li Danan, Kenzo Soejima, Soo A. Ross, Costa B. Daniel, Kwok-Kin Wong, Susumu S. Kobayashi. β-catenin plays an important role in lung tumor development induced by EGFR mutations. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 968. doi:10.1158/1538-7445.AM2014-968