Research of signaling pathway of vascular endothelial growth factor regulating by hepatitis B virus X protein

Abstract

To study the function of nuclear factor-kappaB (NF-kappaB) signaling pathway in regulating vascular endothelial growth factor (VEGF) by hepatitis B virus X protein (HBx). After the establishment of L02-HBx cell line with stable transfected HBx gene, NF-kappaB signaling pathway blocker PDTC was introduced to cut off its signal transduction. Double immunofluorescent staining and laser scanning confocal microscopy were applied to study the activation and deactivation of NF-kappaB signaling pathway. Real-time PCR and Western blot were used to observe the expression of VEGF gene before and after the HBx transfection, as well as the treatment with PDTC. The NF-kappaB signaling pathway of L02-HBx cells was activated after transfection with HBx gene as compared to the control L02 cells without treatment. The mRNA and protein levels of VEGF in L02-HBx cells increased 4.07 +/- 0.31 and 4.34 +/- 0.64 times respectively. The difference was of statistical significance (P < 0.05) in comparison with the control cells. The mRNA levels of VEGF decreased to 2.33 +/- 0.22 and 1.86 +/- 0.18(P < 0.05) and at the same time the expression of VEGF also reduced to 2.52 +/- 0.29 and 2.17 +/- 0.34 (P < 0.05), after treatment with 25.0 micromol/L and 50.0 micromol/L PDTC for 24 h respectively when the NF-kappaB signaling pathway was blocked. There was no significant difference in VEGF mRNA and protein levels when treated with 12.5 micromol/L PDTC for 24 h. NF-kappaB signaling pathway maybe one of the routes through which HBx up-regulate the expression of VEGF to promote angiogenesis in hepatocellular carcinoma.