Oncogenic USP3 promotes hepatocellular carcinoma progression via K11/K48-specific deubiquitination and stabilization of YAP.

Hepatocellular carcinoma (HCC) has a poor prognosis, necessitating therapeutic targets, while the role of ubiquitin-specific protease 3 (USP3) in HCC remains unclear. This study aimed to elucidate the function of the deubiquitinating enzyme USP3 in HCC. USP3 was found to be highly expressed in HCC tissues and associated with poor prognosis. Functional assays in cells and animal models confirmed that USP3 promotes tumor proliferation, migration, and invasion. Mechanistically, USP3 directly binds to yes1-associated transcriptional regulator (YAP) via its ubiquitin C-terminal hydrolase (UCH) domain interacting with YAP's WW domain, removing K11/K48-linked polyubiquitin chains to stabilize the YAP protein. The screening results showed that the pan-deubiquitinating enzyme (DUB) inhibitor PR-619 could inhibit USP3 activity to a certain extent and significantly suppress the growth and metastasis of HCC. Notably, YAP overexpression partially reversed this inhibition. In conclusion, USP3 drives HCC progression by deubiquitinating and stabilizing YAP, and PR-619 demonstrates anti-tumor efficacy, establishing USP3 as a potential therapeutic target for HCC.