Activation of YAP1 by STK25 contributes to the progression of hepatocellular carcinoma

A pathogenic role of serine/threonine protein kinase 25 (STK25) has been observed in several chronic liver diseases. However, whether STK25 participates in hepatocellular carcinoma (HCC) remains unexplored. The current work aimed to explore the role and mechanism of STK25 in HCC. A high STK25 level was found in HCC tissue, which was associated with reduced overall survival. HCC cells with STK25 silencing displayed a marked decrease in proliferative and invasive ability, but were highly sensitive to apoptosis induced by the chemotherapy drug sorafenib. Reciprocally, HCC cells with forced expression of STK25 displayed the opposite effects. Further data unveiled that STK25 silencing restrained the activation of Yes-associated protein 1 (YAP1) associated with regulation of mammalian STE20-like protein kinase 1/2 (MST1/2). Forced expression of constitutively active YAP1 abolished STK25 silencing-induced antitumor effects, while repression of YAP1 reversed STK25 upregulation-induced protumor effects. Additionally, HCC cells with STK25 silencing exhibited reduced tumorigenic potential in vivo. Collectively, the results show that STK25 exerts a protumor function in HCC by enhancing YAP1 activation via regulation of MST1/2. These findings propose STK25 as a viable target for the development of anti-HCC therapy.