Clinical Significance of Ubiquitin Specific Protease 7 (USP7) in Predicting Prognosis of Hepatocellular Carcinoma and its Functional Mechanisms

BACKGROUND Hepatocellular carcinoma (HCC) accounts for one of the most prevalent cancer types in the world. The ubiquitin specific protease 7 (USP7), a kind of deubiquitylating enzyme, has been reported to play multifaceted roles in different tumor types. The aim of this study was to investigate the expression and function of USP7 in HCC. MATERIAL AND METHODS Immunohistochemical staining and quantitative PCR were performed to explore the expression of USP7 in both HCC tissues and adjacent normal liver tissues. Chi-square test, univariate analysis, and multivariate analysis were conducted to statistically evaluate the clinical significance of USP7 in HCC. Proliferation, migration, and invasion capacities of HCC cells were assessed after overexpressing or silencing USP7. RESULTS Both the RNA and protein levels of USP7 were upregulated in HCC tissues compared to normal liver tissues. High expression of USP7 was correlated with advanced tumor stage and poor overall survival. Moreover, USP7 was identified as a novel independent prognostic factor for HCC patients. Cellular studies showed that USP7 could enhance the proliferation, migration, and invasion capacities of HCC cells, thereby promoting tumor progression. CONCLUSIONS High expression of USP7 is frequent in HCC tissues, which promotes tumor proliferation and invasion, and is correlated with a poor overall survival. Targeting USP7 may be a novel direction for the drug development of HCC therapy.