USP8 positively regulates hepatocellular carcinoma tumorigenesis and confers ferroptosis resistance through ß-catenin stabilization.

ABSTRACT

Hepatocellular carcinoma (HCC) is the most common type of primary hepatic carcinoma, which is a growing public health problem worldwide. One of the main genetic alterations in HCC is the deregulated Wnt/ß-catenin signaling, activation of ß-catenin is associated with the progression of HCC. In the present study, we aimed to identify novel modulators in controlling ß-catenin ubiquitination and stability. USP8 was overexpressed in HCC tissues and correlated with ß-catenin protein level. High expression of USP8 indicated poor prognosis of HCC patients. USP8 depletion significantly decreased ß-catenin protein level, ß-catenin target genes expression and TOP-luciferase activity in HCC cells. Further mechanistic study revealed that the USP domain of USP8 interacted with the ARM domain of ß-catenin. USP8 stabilized ß-catenin protein via inhibiting K48-specific poly-ubiquitination process on ß-catenin protein. In addition, USP8 depletion inhibited the proliferation, invasion and stemness of HCC cells and conferred ferroptosis resistance, which effects could be further rescued by ß-catenin overexpression. In addition, the USP8 inhibitor DUB-IN-3 inhibited the aggressive phenotype and promoted ferroptosis of HCC cells through degradation of ß-catenin. Thus, our study demonstrated that USP8 activated the Wnt/beta-catenin signaling through a post-translational mechanism of ß-catenin. High expression of USP8 promoted the progression and inhibited ferroptosis of HCC. Targeting the USP8 may serve as a promising strategy for patients with HCC.