MST1 inhibits cell proliferation and invasion of non-small-cell lung cancer by regulating YAP phosphorylation and Hippo pathway.

Mammalian ste20-like kinase 1 (MST1) is a Ser/Thr kinase involved in cell proliferation, apoptosis, and embryonic development. MST1 is also an important member of the Hippo pathway which can regulate organ size and cell proliferation. Growing evidence indicates that MST1 influences cell proliferation through different pathways including Wnt, Akt, JNK, and Hippo pathways in different cells respectively. However, little is known about the role and mechanism of MST1 in lung cancer. In this study, we aimed to assess the biological functions of MST1 in non-small-cell lung cancer (NSCLC). We investigated expression of MST1 in lung cancer cell lines and one human bronchial epithelium cell line (HBE) by Western blot. The results confirmed that MST1 expression was higher in HBE cells, but significantly lower in NSCLC cells. Moreover, MST1 was either overexpressed or depleted in NSCLC cell lines, and the results confirmed that MST1 could markedly inhibit cell proliferation and invasion through regulating the Hippo pathway and Yes-associated protein (YAP) phosphorylation. These results indicate that MST1 may play an important role in NSCLC and may serve as a potential therapeutic target for NSCLC.