aYAP1-2 contributes to bFGF-induced proliferation In gastric cancer.

Gastric cancer (GC) is one of the leading causes of cancer-related deaths in humans worldwide. Fibroblast growth factor family (FGFs) and the Hippo signaling pathway play an important role in the epithelial-mesenchymal transition (EMT) process of GC. YAP1, a key mediator of the Hippo pathway, plays an important role in tumor genesis. Alternative splicing of human YAP1 mRNA results in two major isoforms: YAP1-1, which contains a single WW domain, and YAP1-2, which contains two WW domains, respectively. There are significant differences in post-transcriptional regulation and function. Basic FGF (bFGF) treatment promoted the EMT process of most GC cell lines, and the proliferation ability was enhanced. This process may be related to the upregulation of YAP1, the proliferation ability of GC was significantly alleviated upon YAP1 knockdown. bFGF treatment can induce EMT of GC through YAP1-2 and enhance their proliferative ability. In this process, bFGF may enhance the nuclear localization of YAP1-2.In the mouse model of intraperitoneal implantation tumorigenesis, it was shown that under the action of bFGF, the expressing YAP1-2 cell lines could form larger tumors than the expressing YAP1-1, but both of them were larger than the YAP1 knockdown. Our results show that YAP1-2 is the main subtype of bFGF-induced EMT and proliferation of GC cells.