The Study Of Hepatitis B Virus PreS1 Gene Promoting The Appearance And Self-Renewal Of Liver Cancer Stem Cells

Hepatocellular carcinoma (HCC) is one of the most common primary malignant tumors.Hepatitis B virus(HBV)is one of the major causes of hepatocellular carcinoma.However,the molecular mechanism by which HBV infection contributes to the pathogenesis of HCC is still not fully understood.We learned from the literature that cancer stem cells as a source of cancer produced,and cancer stem cells can directly promote the occurrence of cancer,so we want to study the causes of HBV-mediated HCC from cancer stem cells.In order to study the difference between hepatocarcinoma cells and normal hepatocytes,we detected the mRNA expression levels of stem cell-related factors(Klf4,c-Myc,Nanog,Oct4 and Sox2)and hepatocellular stem cells surface markers(CD90,CD117 and CD133)expression levels of hepatoma cell line HepG2 and liver cell line L02.HepG2 cell line is a cancer cell line,and its stem cell-related factor mRNA levels and expression of cancer stem cells markers is much higher than the L02 cell line.This finding tells us that the process of transformation of hepatocytes into hepatocarcinoma cells is closely related to cell dedifferentiation and cancer stem cell-related factor.Then we compared the hepatocarcinoma cell line HepG2 and HepG2.2.15(derived from HepG2 but carrying the HBV genome).We found that the mRNA expression levels of stem cell-related factor in HepG2.2.15 cells was significantly higher than that in HepG2 cells.The expression levels of CD90,CD117 and CD 133 in HepG2.2.15 cells were also significantly higher than those in HepG2 cell lines.We also found that the proliferation and migration ability of HepG2.2.15 cells was stronger than that of HepG2 cells in cell growth experiments.These results indicated that liver cancer cell line HepG2.2.15 have higher liver cancer stem cell level than HepG2 cell line.According to the previous literature,HBx and preS/S protein,which is generated in hepatitis B virus life cycle,may be involved in hepatocellular carcinoma.It also been reported that HBx and preS2 may be associated with the occurrence of hepatocellular stem cells.So in this study some experiments were designed to verify the ability of the relevant proteins HBx,preS1 and preS2 to transform hepatocytes into hepatocarcinoma stem cells.We stably expressed HBx,preS1 and preS2 genes in hepatocyte cell line L02 and HCC cell line HepG2,respectively.Before we examined the cancer stem cell markers of the constructed cell lines,we surprisedly found that the growth and cell morphology of L02 which stable expressed pre-S1 protein changed dramatically.Then we examined the cancer stem cell related factors of preS1 stably expression cell lines and found that preS1 significantly increased the level of cancer stem cells in the corresponding cell lines.PreS1 not only increased the mRNA expression level of stem cell-related factor but also increased surface marker expression level of cancer stem cells.Other experiments also confirmed that preS1 gene could promote the self-renewal and proliferation of L02 liver cell line.All these results indicated that PreS1 protein of hepatitis B virus was an important factor leading to the appearance and development of liver cancer stem cells.