Hepatitis B core antigen promotes invasion of hepatocellular carcinoma cell line HepG2.2.15 via Toll-like receptor 4 / 中华肝脏病杂志

ABSTRACT

Objective@#To investigate the effect of hepatitis B core antigen (HBcAg) in promoting the invasion of hepatitis B virus (HBV)-related hepatocellular carcinoma cell line HepG2.2.15 and the role of Toll-like receptor 4 (TLR4) in the mechanism.@*Methods@#TLR4 mRNA and protein expression in HepG2 cells and HepG2.2.15 cells was measured by reverse transcription real-time PCR and Western blot analysis, respectively. HepG2.2.15 cells were transfected with TLR4 specific small interfering RNA (siRNA) to silence TLR4 expression, and stimulated by recombinant HBcAg in culture. The invasion of cells was measured by Transwell invasion assay. The expression of TLR4 signaling pathway-related proteins in the cultured cells and proinflammatory cytokines in the supernatant was also determined. The student’s t-test, one-way ANOVA, and SNK-q test were used for statistical analysis.@*Results@#TLR4 mRNA and protein expression in HepG2.2.15 cells was significantly higher than that in HepG2 cells. TLR4 siRNA transfection remarkably down-regulated TLR4 expression in HepG2.2.15 cells. Inhibiting TLR4 expression and/or HBcAg stimulation did not affect the proliferation of HepG2.2.15 cells. However, HBcAg stimulation significantly increased the invasion ability of HepG2.2.15 cells and the secretion of proinflammatory cytokines [including interferon (IFN)-γ, interleukin (IL)-6, IL-8, and tumor necrosis factor (TNF)-α]. Inhibiting TLR4 expression significantly reduced HBcAg-induced cellular invasion. Meanwhile, HBcAg stimulation elevated the expression of MyD88 and TRIF in HepG2.2.15 cells. TLR4 silencing inhibited HBcAg-induced increase in the expression of MyD88, while it showed no significant impact on TRIF expression.@*Conclusion@#HBcAg can promote the invasion of HepG2.2.15 cells. The TLR4/MyD88 signaling pathway may be involved in this process by inducing the expression of proinflammatory cytokines.