Abstract 2146: YAP is an important pathway downstream of EGFR that is a potential target for EGFR-TKI-resistance lung adenocarcinomas

Epidermal growth factor receptor (EGFR) mutations are found in lung adenocarcinomas leading to tumor cells proliferation and survival. EGFR tyrosine kinase inhibitors (TKIs) that block EGFR activity are effective therapeutics for EGFR-mutant lung adenocarcinoma patients, but TKI-resistance inevitably occurs. The YES-associated protein (YAP) transcription coactivator has been implicated as an oncogene and is amplified in human cancers and provides tumor cells strong proliferation and survival cues. This study investigated the roles of YAP in lung adenocarcinoma by exploring its regulation and functions mediated by EGFR signaling. Using lung adenocarcinoma cell lines, we detected enhanced YAP expression and activity mediated by EGFR signaling due to enhanced protein stability. The Src family protein YES was involved in EGFR-regulated YAP expression. The YAP/YES pathway was crucial for proliferation in EGFR-dependent cells. Small molecules that reduced YAP levels by mechanisms bypassing EGFR were effective in killing EGFR-dependent cells including EGFR T790M, the major cause of TKI-resistance. These observations unveiled the significance of YAP in EGFR mutant lung adenocarcinomas and identified YAP as an promising therapeutic target for EGFR-dependent lung adenocarcinoma patients, including those with EGFR T790M-caused TKI resistance. Citation Format: Ting-Fang Lee, Yu-Chi Tseng, Ying-Pu Liu, Yu-Rung Kao, Cheng-Wen Wu. YAP is an important pathway downstream of EGFR that is a potential target for EGFR-TKI-resistance lung adenocarcinomas. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2146.