Golgi Protein 73 (GP73) is a newly identified diagnostic and prognostic marker for liver cancer. GP73 is highly expressed in liver cancer tissues, however, the mechanism of its overexpression in tumors remains unknown. In the present study, the effect of hepatitis B virus (HBV) on GP73 expression was investigated in HepG2 cells, which are negative for HBV, and in HepG2.2.12 cells, which are integrated with HBV, using reverse transcription-quantitative polymerase chain reaction and western blot analysis. In addition, the cells were transfected with plasmid constructs overexpressing hepatitis B virus protein X (HBx), hypoxia-inducible factor (HIF)-1α, or HIF-2α in order to examine their roles in GP73 expression. The results demonstrated that HBV upregulated the expression of GP73 and HIF-2α in liver cancer cells. HIF-2α induced the expression of GP73 in HepG2 cells and was positively correlated with GP73 expression in liver cancer tissues. By contrast, HBx and HIF-1α did not induce GP73 expression in liver cancer cells. In summary, HBV may upregulate the expression of GP73 by activating the HIF-2α signaling pathway. The present results may illuminate the mechanism by which GP73 is overexpressed in liver cancer tissues.
Keywords: Golgi protein 73; hepatitis B virus; hepatitis B virus protein X; hepatocellular carcinoma; hypoxia-inducible factor-1α; hypoxia-inducible factor-2α.