Association of YAP1 activation with poor patient prognosis and effect on chemoresistance in gastric cancer.

4113 Background: Clinical heterogeneity in gastric cancer is likely due to biological differences among patients. Molecular subtypes and their associated biomarkers need to be established to improve treatment of this disease. We aimed to uncover subgroups of gastric cancer that have distinct biological characteristics associated with clinical outcome and to identify potential best treatments or therapeutic targets for each subgroup. Methods: We analyzed gene expression profiling data from gastric cancer cell lines and 267 patients with gastric cancer to uncover tumor subtypes and identify a gene expression signature associated with prognosis and response to adjuvant chemotherapy. The association of the signature with prognosis was validated in an independent cohort of 200 patients, and its association with response to adjuvant therapy was validated by cell culture experiments. Results: We identified an expression signature of 88 genes that specifically reflected activation of the oncogene YAP1. Compared w...