Effects Of Hepatitis B Virus On AKR1C1 Gene Expression In Hepatoma Cells

The HBV infection ranks second among all kinds of infectious diseases and its death rate ranks third. Currently, there are approximately 350,000,000 HBV carriers all over the world. The infection of HBV may cause different types of acute and chronical viral hepatitis and cirrhosis and it is closely related to hepatic cancer. However, the detail mechanism of HBV infection is now still debatable and no final conclusion has yet been reached on the mechanism of inducing cytopathic effects.The products encoded by HBV genome play an important role in its life cycle and the process of causing diseases, the X protein from the products is considered to be a multifunctional regulatory protein. It is associated with the gene transcription, protein degradation and apoptosis process. AKR1C1 gene encodes aldo-keto reductase 1C1 and expresses excessively in many tumors, which is related to the drug resistance of antineoplastic drugs. Some researchers found that the expression of AKR1C1 in hepatoma carcinoma cell which expresses HBx stablely is higher than that in the HBx-untransfected hepatic cancer cells by using genechip. This result shows that HBV gene products may play a regulatory role in AKR1C1 expression of the hepatic cancer cells. This thesis analyzed the influence of HBV on the gene expression of AKR1C1 in hepatic cancer cells and studied the regulatory mechanism of HBV.AKR1C1 gene expression on mRNA level in HepG2 and HepG2.2.15 cell lines was detected by RT-PCR and Real-time PCR. According to the results, the AKR1C1 gene expression in HepG2.2.15 cells was 1.5 times higher than that in HepG2 cells. On this basis, we successfully constructed AKR1C1 promoter luciferase reporter plasmid and transiently co-transfected respectively with the HBV expression plasmid and the expression plasmids of four proteins that the HBV encode: HBx, HBs, HBc and HBp in HepG2 cells. Through the dual-luciferase detection system, we detected the luciferase activity. As the result suggested, in the HepG2 cells, which were co-transfected with the HBV expression plasmids and the AKR1C1 promoter luciferase reporter plasmids, the luciferase activity has enhanced greatly, which was 3.37 times higher than the control group. Compared with HBs,HBp and HBc,the relative luciferase activity in HepG2 cells transfected with HBx expression plasmids was much higher.Our research showed that HBV can up-regulate AKR1C1 expression in hepatoma cells, its mechanism may be achieved by effect on the AKR1C1 gene's promoter, and HBx plays an important role in the transcriptional activation. The results provide us a new way to explore the pathogenic mechanism of HBV induced liver cancer.