The oncogenic role of MST3 in human gastric cancer.

MST3 (mammalian STE20-like kinase) is one of the protein kinase of the GCK III subfamily STE 20, and is known to play a role in cell growth and apoptosis. Our laboratory has demonstrated that MST3 promotes tumorigenicity through the VAV2/Rac1 signal axis in breast cancer. In this report, we further investigated the potential oncogenic role of MST3 in gastric cancer. Examination of tissue samples from 101 gastric cancer patients revealed that higher expression of MST3 was observed in tumor part with immunohistochemistry. Furthermore, high expression of MST3 predicts poor prognosis in gastric cancer patients. To investigate the function of MST3 in vitro, MKN45 and NCI-N87 cell lines were transfected with the MST3 shRNA and stable clones were established. Downregulation of MST3 inhibited cell proliferation. The p21 expression was enhanced by MST3 shRNA in MKN45 gastric cancer cell line. Finally, downregulation of MST3 attenuated the anchorage-independent growth in soft agar and tumor growth in NOD/SCID mice. Altogether, our results indicate that MST3 potentially plays an oncogenic role in gastric cancer.