Hepatitis B virus X protein inhibits hepatoma cell growth in vitro through p14(ARF)-dependent and p14(ARF)-independent pathways.
- Author:
Dang-Hui YU
1
;
Jing LIN
;
Jian-Hui QU
;
Zhi ZHU
;
Fang-Mei LI
;
Can-Rong NI
;
Ming-Hua ZHU
Author Information
- Publication Type:Journal Article
- MeSH: Carcinoma, Hepatocellular; genetics; pathology; virology; Cell Line, Tumor; Cell Proliferation; Cyclin-Dependent Kinase Inhibitor p21; genetics; Humans; Liver Neoplasms; genetics; pathology; virology; Promoter Regions, Genetic; Trans-Activators; genetics; Transfection; Tumor Suppressor Protein p14ARF; genetics; Tumor Suppressor Protein p53; genetics
- From: Journal of Southern Medical University 2009;29(6):1089-1093
- CountryChina
- Language:Chinese
-
Abstract:
OBJECTIVETo explore the effects of hepatitis B virus X protein (HBx) on hepatoma cell growth through p14(ARF)-dependent and p14(ARF)-independent pathways.
METHODSHBx and p14(ARF) were transfected either separately or in combination into HepG2 cells containing wt-p53 but not expressing p14(ARF). The cells were divided into 4 groups, namely pcDNA3 (control), pcDNA3HBx, pcDNA3p14(ARF), and pcDNA3HBx + pcDNA3p14(ARF) groups. Flow cytometry was used to examine the apoptosis rates and cell cycle progression of HepG2 cells in different groups. The expression of p14(ARF), MDM2, p53, and p21(WAF1) proteins were investigated by detecting the activity of p21(WAF1) promoter-luciferase and using Western blotting.
RESULTSThe apoptosis rates of HepG2 cells in pcDNA3HBx and pcDNA3p14(ARF) groups were significantly higher than that in the control group (14.11%, 13.72% vs 10.66%). Compared with the control group, pcDNA3HBx and pcDNA3p14(ARF) groups also showed significantly higher cell percentages arrested at G(0)/G(1) phase (63.62%, 61.75% vs 57.42%), luciferase activity of p21 promoter (1.25-/+0.05, 1.09-/+0.06 vs 0.77-/+0.03) and expressions of p53 and p21(WAF1). The cell apoptosis rate, percentage of cells in G(0)/G(1) phase and expression level of p14(ARF) were even higher in pcDNA3HBx+pcDNA3p14(ARF) group (18.61%, 66.74%, and 3.53-/+0.43, respectively) than in either p14(ARF) or HBx group.
CONCLUSIONHBx induces p53 expression through p14(ARF)-dependent and independent pathways to activate p21(WAF1) promoter, leading to G(0)/G(1) arrest and apoptosis of HepG2 cells.
