Abstract: Objective This experiments aimed to explore the effects of core proteins of different quasispecies of genotype 1b hepatitis C virus (HCV) on the biological behaviors of HepG2 cells in vitro. Methods The eukaryotic plasmids of genotype 1b HCV center strain (T), para-carcinoma strain (NT) and C191 strain (HCV-J6) were constructed, and the HepG2 cells were transfected by them, e.g., pcEGFP-T, pcEGFP-NT and pcEGFP-C191 group by Lipofectamine 2000. The cells proliferation was detected by plate clone method, and the relative levels of cell proliferation related genes, such as PCNA, Ki67, Cyclin B and CDK1 mNRA were detected by fluorescent quantitative PCR. The cells were treated with tumor necrosis factor-α (TNF-α) at dose of 50 ng/mL for 8 h. The apoptosis was detected by flow cytometry. The expressions of apoptosis-related proteins Bax/Bcl-2, Caspase-3 and Caspase-9 and invasion-related proteins of MMP-3, MMP-9 and Snail were detected by Western blot. Results The clone formation rates in pcEGFP-NT-, pcEGFP-T- and pcEGFP-C191-transfected HepG2 cells were (57.3±4.2)%, (64.5±3.8)% and (49.8±3.2)%, significantly higher than [(44.3±3.4)%, P<0.05] in empty plasmid-transfected cells, while the apoptosis was significantly weaker than that in empty plasmid group; the relative levels of PCNA, Ki67, Cyclin B and CDK1 mNRA in pcEGFP-NT group were (1.5±0.0), (1.7±0.1), (1.6±0.0) and (1.8±0.1), significantly higher than [(1.0±0.1), (1.0±0.1), (1.0±0.1) and (1.0±0.1), respectively, P<0.05] in empty plasmid group, those in pcEGFP-T group were (1.9±0.1), (2.1±0.1), (2.3±0.1) and (2.6±0.1), significantly higher than in empty plasmid group (P<0.05) and those in pcEGFP-C191 group were (1.2±0.1), (1.4±0.1), (1.4±0.0) and (1.5±0.0), significantly higher than those in empty plasmid group (P<0.05); the expression levels of Bax/Bcl-2, Caspase-3 and Caspase-9 in pcEGFP-NT group, pcEGFP-T group and pcEGFP-C191 group were significantly weaker than those in empty plasmid group, while the expression levels of MMP-3, MMP-9 and Snai proteins were significantly stronger than those in empty plasmid group. Conclusion The intensified expression of HCV core protein by special quasispecies of HCV infection might improve the proliferation and anti-apoptosis abilities of HepG2 cells in intro.

Key words: HepG2 cells, Hepatitis C virus, Core protein, Cell proliferation, Apoptosis, In vitro