HBV Facilitated Hepatocellular Carcinoma Cells Proliferation by Up-Regulating Angiogenin Expression Through IL-6

Abstract

Background/Aims: Patients with hepatitis B virus (HBV) infection are at a high risk of developing hepatocellular carcinoma (HCC). In this study, we aim to investigate the roles of HBV on angiogenin (ANG), as well as the effects on cell proliferation in presence of ANG down-regulation. Methods: Serum ANG was determined by ELISA. The expression of ANG mRNA and protein in HCC cell lines with or without HBV/HBx were determined. Western blot and ELISA were conducted to determine the effects of HBV/HBx on IL-6 expression. The role of IL-6 on ANG was evaluated by IL-6 recombinant protein or IL-6 neutralizing antibody. Immunofluorescence staining was used to detect the nuclear translocation of ANG. MTT was performed to evaluate the relative inhibition ratio. Result: In vivo experiments showed elevation of serum ANG in patients infected with HBV. In vitro experiments showed HBV and HBx contributed to the transcription and translation of ANG. ANG expression showed increase after IL-6 stimulation, and ANG protein decreased in the presence of IL-6 blocking with its antibody. HBV promoted nuclear translocation of ANG. Inhibiting ANG expression or blocking of nuclear transfer of ANG attenuated the 45S rRNA synthesis and cell proliferation. Conclusion: HBV and HBx protein can increase the level of ANG through IL-6. HBV and HBx contributed to the nuclear translocation of ANG. Cell proliferation was inhibited after inhibiting the expression or nuclear transfer of ANG.