Effects and related mechanisms of serotonin on malignant biological behavior of hepatocellular carcinoma via regulation of Yap

5-hydroxytryptamine (5-HT, serotonin) and Yes-associated protein (Yap), which act as a mitogen and an oncogene, respectively, play an important role in tumors. Here, we investigated whether 5-HT could affect the hepatocarcinogenic process via promoting the activation and expression of Yap, as well as the possible underlying molecular mechanisms. We found that 5-HT promoted hepatoma cell proliferation, invasion and metastasis via regulating Yap expression in vitro and in vivo, and Yap knockdown had opposite effects. Furthermore, 5-HT activated 5-5-HT_2BR to promote Yap expression via upregulating the pERK level. Inhibitors of 5-5-HT_2BR and ERK attenuated the overexpression of Yap and promotional effects of 5-HT in vitro and in vivo. As a result, 5-HT affected the malignant biological behavior of hepatoma cells via the 5-HT-5-HT_2BR-pERK-Yap axis. Therefore, 5-HT and Yap may be prognostic predictors and potential therapeutic targets for HCC patients in the future.