Blocking inhibition to YAP by ActinomycinD enhances anti-tumor efficacy of Corosolic acid in treating liver cancer.

Chemotherapy is critical for the treatment of liver cancer. Despite the pro-apoptotic effects of corosolic acid (CA) have been revealed, the methods to enhance its efficacy are unclear. The aim of this study is to investigate the target that might reduce CA efficacy and figure out the way to conquer it. We found reduction of Yes-associated protein (YAP) might be a critical event that suppresses efficacy of CA. Treatment of CA accelerated degradation of YAP via enhancing its phosphorylation by LATS1. Moreover, we found CA boosts βTrCP-dependent Ubiquitination of YAP. Interestingly, the protein stability of βTrCP per se could be enhanced by CA. Notably, ActionomycinD (AD) strengthened CA-induced apoptosis of liver cancer cells via elevating YAP while down-regulating βTrCP. Importantly, combined treatment of CA and AD had much more obvious influences against transformative phenotypes of liver cancer cells than those under treatment of CA alone. Combined usage of AD successfully reduced IC50 value of CA. In summary, we have first uncovered that suppression of YAP might reduce efficacy of CA to treat liver cancer, combined treatment of AD and CA might solve this problem.