title: Hepatitis C virus F protein inhibits cell apoptosis by activation of intracellular NF-kappaB pathway.
abstract: OBJECTIVE
  To observe the influence of HCV F protein on apoptosis of HepG2 cells, and explore the association between F protein and NF-kappaB signal pathway.
  
  
  METHODS
  HCV 1b F gene containing HepG2-F cells and HCV 1b C gene containing HepG2-C cells were treated with 100 IU/mL TNF-alpha, and analyzed by flow cytometry, Western blotting, and dual luciferase reporter assay. Empty plasmid pcDNA3.1(+) containing HepG2-3.1 cells were used as control.
  
  
  RESULTS
  (i) With the treatment of TNF-alpha for 18 h, the apoptosis rates (AR) of HepG2-F and HepG2-3.1 cells were 0.41% (+/- 0.11%) and 37.43% (+/- 2.03%) respectively, while that of HepG2-C was 4.07% (+/- 0.18%). At 36 h after TNF-alpha treatment, the AR of HepG2-F and HepG2-3.1 cells were 10.03% (+/- 0.41%) and 44.63% (+/- 3.37%), and that of HepG2-C was 14.95% (+/- 0.85%). (ii) After the treatment of TNF-alpha for 0.5-18 h, the p65 contents in the whole cells of HepG2-F and HepG2-3.1 showed no significant difference (P = 0.34, t = 1.08), while the p65 contents in the nucleus of HepG2-F and HepG2-3.1 cells were 3.8-1.9 times and 1.8-1.0 times higher than that in the non-treated cells (P = 0.013, t = 4.25). (iii) The relative luciferase unit (RLU) of the HepG2 cells, co-transfected with pcDNA3.1-F and pNF-kappaB-luc, and then treated with TNF-alpha (100 IU/mL) for 18 h, showed a pcDNA3.1-F dose-dependent increase.
  
  
  CONCLUSIONS
  HCV F protein can over-activate NF-kappaB signal pathway, which makes HepG2-F cells able to resist TNF-alpha induced apoptosis.
authors.affiliation: Department of Microbiology, Shanghai Key Laboratory of Medical Biodefense, Second Military Medical University, Shanghai, China.
authors.forename: Sheng-Wen
authors.initials: SW
authors.lastname: Shao
authors.forename: Wen-Bin
authors.initials: WB
authors.lastname: Wu
authors.forename: Zhong-Qi
authors.initials: ZQ
authors.lastname: Bian
authors.forename: Jian-Guo
authors.initials: JG
authors.lastname: Yu
authors.forename: Ping
authors.initials: P
authors.lastname: Zhao
authors.forename: Lan-Juan
authors.initials: LJ
authors.lastname: Zhao
authors.forename: Shi-Ying
authors.initials: SY
authors.lastname: Zhu
authors.forename: Zhong-Tian
authors.initials: ZT
authors.lastname: Qi