[Molecular mechanism of HCV NS5A on p53's inhibition of AFP expression in hepatocellular carcinoma cells].
OBJECTIVE
To explore hepatitis C virus (HCV) non-structural protein 5A (NS5A)'s influence on inhibition of AFP expression executed by p53 protein and its possible molecular mechanism.


METHODS
Plasmid transfection and MEIA were employed to observe p53's inhibitive effect on AFP expression of Huh7 cells and the HCV NS5A's influence on p53 function. Western blot was employed to find out if HCV NS5A affects p53 protein expression and GST pull down assay was applied to examine the interaction between HCV NS5A and p53.


RESULTS
The AFP concentration in the supernatant of the culture of the Huh7 cells transfected with pRc/CMV was (14322+/-2412) ng/ml, and that of the Huh7 cells transfected with pCNS5A was (13843+/-3218) ng/ml; no significant difference existed between these two groups (t = 1.42, P > 0.05). After transfection with pC53-NS3, the AFP level was decreased to (10 241+/-1326) ng/ml, and in comparison to the above two groups it had a statistically significant difference (t values were 2.41 and 2.38, P < 0.05). When co-transfected with pCNS5A and pC53-NS3, the AFP expression (14582+/-1238) ng/ml returned to the level of pRc/CMV transfected, and there was a remarkably significant difference between this and that of the pC53-NS3 transfected cells (t = 3.12, P < 0.01). HCV NS5A had no function on the p53 protein expression with Western blot experiment. In the GST pull down assay, an HCV NS5A protein band was found after GST-p53 was added, but not detected with GST only.


CONCLUSIONS
We found that p53 has an inhibitive function on the AFP expression in Huh7 cells and HCV NS5A minimized this p53 function. HCV NS5A did not affect p53 protein expression, but was able to form a complex with p53, by which HCV NS5A inactivated this p53 function.
Gong
Guo-zhong
GZ
The Center for Liver Diseases, Second Xiangya Hospital, Central South University, Changsha 410011, China. guozhonggong@yahoo.com
Jiang
Yong-fang
YF
He
Yan
Y
Lai
Li-ying
LY
Xu
Yun
Y
Su
Xian-shi
XS
D006528:Carcinoma, Hepatocellular / Q000378:metabolism* / Q000821:virology; D016174:Hepacivirus / Q000235:genetics*; D006801:Humans; D008113:Liver Neoplasms / Q000378:metabolism* / Q000821:virology; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000494:pharmacology; D017361:Viral Nonstructural Proteins / Q000235:genetics*; D000509:alpha-Fetoproteins / Q000096:biosynthesis* / Q000235:genetics; D012324:RNA-Dependent RNA Polymerase
D016159:Tumor Suppressor Protein p53; D017361:Viral Nonstructural Proteins; D000509:alpha-Fetoproteins; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase