USP24 promotes hepatocellular carcinoma tumorigenesis through deubiquitinating and stabilizing TRAF2

Ubiquitin-specific peptidase 24 (USP24), a member of the deubiquitinase family, plays an important role in tumor regulation. However, the role of USP24 in Hepatocellular carcinoma(HCC)is unknown. The aim of our study was to explore the role of USP24 in HCC to seek new therapeutic targets for HCC. In this study, we found that USP24 was aberrantly upregulated in HCC tissues and predicted poor prognosis. USP24 markedly promoted HCC proliferation and progression in vitro and in vivo. Mechanistically, USP24 binds to tumor necrosis factor receptor-associated factor 2(TRAF2) and inhibits its degradation, thereby promoting the accumulation of TRAF2. Upregulation of TRAF2 activated protein kinase B/nuclear factor kappa-B (AKT/ NF-kappa B) signaling pathway and promoted HCC cell survival. In addition, USP24 positively correlated with programmed cell death ligand 1(PDL1) expression in HCC, highlighting the clinical significance of USP24 activation in tumor immune evasion. Deletion of USP24 enhanced the tumor-killing ability of CD8+ T cells. Deletion of USP24 combined with anti-PD1 antibody significantly enhanced the efficacy of HCC immunotherapy. Taken together, USP24 can be employed as a promising target to restrain tumor growth and increase the efficacy of HCC immunotherapy.