Knockdown of HBx by RNAi inhibits proliferation and enhances chemotherapy-induced apoptosis in hepatocellular carcinoma cells

The present study was designed to research on RNA interference hepatitis B virus x gene approach to hepatocellular carcinoma (HCC) therapy. Previously, we constructed and identified shRNA eukaryotic expression vectors (pshRNA-X220) specific to HBx gene, pshRNA-MOCK (control); and established HCC cell lines with stable expression shRNA eukaryotic vector targeting HBx gene-21543 cell lines (MHCC97-H of expressing shRNA against HBx), HK3 cell lines (MHCC97-H by transfected with pshRNA-MOCK). We examined the expression of HBx gene after RNA interference by semi-quantitative RT-PCR and assessed the effect of HBx knocked down on cell growth by proliferation assay using kit-8 (CCK8). As well as, we analyzed cell cycle distribution by flowcytometry and examined cell apoptosis using TUNEL assay. The HBx mRNA expression level is reduced, and cells growth was significantly stopped in 21543 cell lines. Cells with HBx knockdown were more sensitive to 5-fluorouracil/cisplatin. RNA interfering HBx induced an obvious time and dose-dependent inhibitory in comparison with the control cells. Meanwhile, RNA interferenced targeting HBx, in combination with chemotherapy can effectively induce apoptosis in hepatocellular carcinoma cells and restricts cell proliferation.

Effects of HBV X gene and arsenic trioxide on the expression of p53 in cultured HepG2 cells

BACKGROUND

Hepatitis B virus (HBV) X protein (HBx) and p53 could mutually down-regulate at transcriptional level and HBx could bind with p53 protein within its transactivation domain and inhibit the function of p53 protein. In recent years, effects of arsenic trioxide (As2O3) on the expression of p53 protein have been widely studied, while little is known about the activity of p53 protein. This study was undertaken to delineate the effect of HBV X gene and As2O3 on p53 protein expression (level and activity) in HepG2 cells by small hairpin RNA (shRNA)-mediated RNA interference (RNAi) technique.

METHODS

Cell line HepG2 and cells with stable expression of HBV X gene (HepG2-X) were treated with 2 micromol/L As2O3, with corresponding untreated cells serving as controls. Cell lysates and nuclear extracts were extracted. Total level and the relative activity of p53 protein were detected by modified enzyme-linked immunosorbent assay (ELISA). HBV X gene sequence-specific shRNA expression vector (pXi-1 and pXi-2) and sequence-unrelated control (pXi-3) were transfected into HepG2-X. Single cell clone with stable expression of shRNA was selected and exposed to propagating culture. The effect of As2O3 on p53 protein expression and activity was re-observed.

RESULTS

Total p53 protein level was up-regulated and its relative activity ratio was enhanced by As2O3 in HepG2 and HepG2-X cells. The total p53 protein level induced by As2O3 was up-regulated by HBV X gene expression, while its relative activity was significantly suppressed. The suppression was removed after HBV X gene expression was repressed by shRNA.

CONCLUSIONS

As2O3 up-regulates p53 protein expression and enhance its activity. HBV X up-regulates As2O3 induced-p53 protein expression while suppresses its activity.

[Construction of two hepatocellular carcinoma cell models for the expression of HBV X gene with different selection characteristics]

OBJECTIVE

To construct 2 hepatocellular carcinoma (HCC) cell models for the expression of HBV X gene with different selection characteristics.

METHODS

HepG2 HCC cells were infected with eukaryotic expression vectors with HBV X gene, pCEP4-X, and pcDNA3. 1 (+)-X. Single cell clone was selected by hygromycin and neomycin. After propagating culture for certain periods, the HBV X gene expression was identified by PCR, RT-PCR, and Western blot.

RESULTS

Single HCC cell clone with HBV X gene transferred resistant to hygromycin and neomycin was selectively cultured, and the cells could be propagated for certain periods. PCR, RT-PCR, and Western blot identified the expression of HBV X gene.

CONCLUSION

Two HCC cell models for the expression of HBV X gene with different selection characteristics have been successfully constructed.