Hepatitis B Surface Antigen Promotes the Invasion of Hepatitis B Virus-Related Hepatocellular Carcinoma Cells by Upregulation of Toll-Like Receptor 2

Hepatitis B virus (HBV) infection is one of the major risk factors leading to the development of hepatocellular carcinoma (HCC). Hepatitis B surface antigen (HBsAg) plays a pivotal role in HBV-related HCC pathogenesis, and Toll-like receptor (TLR) 2 is also considered to mediate tumor progression. However, the interaction between HBsAg and TLR2 in HCC progression remains unclear. Thus, the aim of the study was to explore the effect of HBsAg-TLR2 pathway on growth and invasion of HBV-related HCC cells and examine the potential mechanisms been involved. The expression of TLR2 was measured in two different HCC cell lines (HepG2 and HepG2.2.15) with or without recombinant HBsAg by real-time reverse polymerase chain reaction and Western blot. Cellular proliferation, invasion, cytokine productions, and downstream signaling pathways were also measured in TLR2-silencing HepG2.2.15 cells in response to HBsAg stimulation. The mRNA and protein levels of TLR2 were significantly elevated in HepG2.2.15 cells than those in HepG2 cells. HBsAg simulation increased proinflammatory cytokine production and invasion of HepG2.2.15 cells, while this process was inhibited by TLR2 silence. However, TLR2 siRNA transfection alone did not affect the bioactivities of tumor cells. Moreover, HBsAg increased expression of MyD88 and phosphorylation of NF-κB p50 and p38MAPK. Downregulation of TLR2 inhibited HBsAg-induced MyD88 and p-NF-κB, but not p-p38MAPK in HepG2.2.15 cells. In conclusion, HBsAg stimulation promotes the invasion of HBV-related HCC cells. TLR2/MyD88/NF-κB signaling pathway may be involved in this procession by upregulation of cytokine production. The interaction between TLR2 and HBsAg may contribute to the poor prognosis of HBV-related HCC.