Hepatitis B Virus-X Protein Promoting The Malignant Activity Of Liver Cancer Cells Via Inducing The Expression Of Alpha-Fetoprotein

Objective The hepatitis B virus (HBV)-X protein (HBx) induces malignant transformation of liver cells, and elevated expression of alpha-fetoprotein (AFP), which is a significant biomarker of hepatocarcinogenesis. Alpha-fetoprotein (AFP) governs the expression of some malignancy-related genes such as stromal cell-derived factor-la(SDF-la) receptor CXCR4. However, the role of AFP in HB V-related hepatocarcinogenesis is unclear.Methods Immunohistochemistry was used to detect the expression of AFP, pAKT, p-mTOR and CXCR4 in human HCC tissues; eukaryotic expression vector pcDNA3.1-HBx was transfected into human normal liver cells CHL and L02 and pc DNA3.1-afp was transfected into human liver cancer cell HLE and that the interfering vector AFP-si RNA was transfected into CHL-X, L02-X and PLC/PRF/5; Western Blot was used to analysis the expression of AFP, PTEN, pAKT (Ser473), p-mTOR (Ser2448), Src, Ras, and CXCR4 in liver tissues and liver cells; Co-IP was used to investigate the interaction of AFP with PTEN in liver cells; wound healing assay was used to study the wound healing ability of liver cancer cells; and transwell migaration assay was used to investigate the migaration ability of liver cancer cells.Results Our results indicated that HBV induced the expression of AFP prior to that of oncogenes, e.g., Src, Ras and chemokine (C-X-C motif) receptor 4 (CXCR4) and AFP activated protein kinase B (AKT) in HBV-related HCC tissues, AFP-related HCC tissues and in human liver cells transfected with HBx or AFP. Cytoplasmic AFP interacted with and inhibited phosphatase and tensin homolog deleted on chromosome 10 (PTEN), activating the phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway and upregulating the expression of Src, Ras and CXCR4, and promoting the migatation of HLE cells. On the contrary, interfering the expression of AFP by siRNA in liver cells transfected with HBx and in PLC/PRF/5 cell which producing HBx and AFP resulted in the repression of p-mTOR, pAKT, Src, CXCR4 and Ras in human maliganant liver cells and the inhibiton of migaration of PLC/PRF/5 cell.Conclusions Taken together, our study indicated that HBx could induce the expression of AFP, which could induce the expression of CXCR4 and promote the malignant activity via activating PI3K/AKT signaling pathway...