Hepatitis B virus X protein promotes proliferation and upregulates TGF-beta1 and CTGF in human hepatic stellate cell line, LX-2.
BACKGROUND
Chronic hepatitis B virus (HBV) infection is a major cause of liver fibrosis, but the mechanisms underlying HBV-related fibrogenesis are still unknown. Although the roles of HBV X protein (HBx) remain poorly understood, it is thought to play an important role in the regulation of cellular growth and hepatocarcinogenesis. The aim of this study was to determine the role of HBx in liver fibrogenesis by studying the effect of HBx on the proliferation and expression of fibrosis-related molecules in the human hepatic stellate cell line, LX-2.


METHODS
We established an in vitro co-culture system with LX-2 cells and a stable QSG7701-HBx cell line which had been transfected with the HBx gene. 3H-TdR incorporation and flow cytometry were used to determine the effects of HBx on the proliferation of LX-2 cells. Alpha-smooth muscle actin (alpha-SMA), transforming growth factor-beta1 (TGF-beta1), transforming growth factor-beta receptor II (TGF-betaRII), and connective tissue growth factor (CTGF) in LX-2 cells were analyzed by Western blotting. In addition, the expression levels of collagen type I (ColI) from the co-cultured media were measured by ELISA.


RESULTS
3H-TdR incorporation increased significantly in LX-2 cells co-cultured with QSG7701-HBx cells compared to those cultured with QSG7701-pcDNA3 and QSG7701 (non-tumorigenic human liver cell line). Cell cycle results revealed that HBx accelerated the progression of G1 to S in LX-2 cells. The expressions of alpha-SMA, TGF-beta1, TGF-betaRII, CTGF and ColI were significantly increased in the co-cultures of LX-2 cells with stable QSG7701-HBx cells.


CONCLUSIONS
These results suggest that HBx may facilitate liver fibrosis by promoting hepatic stellate cell proliferation and upregulating the expression of fibrosis-related molecules.
Guo
Guang-Hui
GH
Department of Infectious Diseases, Xiangya Hospital, Central South University, Changsha 410008, China. guanghuiguo2008@yahoo.cn
Tan
De-Ming
DM
Zhu
Ping-An
PA
Liu
Fei
F
D000199:Actins / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D018920:Coculture Techniques; D024042:Collagen Type I / Q000378:metabolism; D055513:Connective Tissue Growth Factor / Q000378:metabolism*; D005434:Flow Cytometry; D055166:Hepatic Stellate Cells / Q000378:metabolism / Q000473:pathology / Q000821:virology; D019694:Hepatitis B, Chronic / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D008103:Liver Cirrhosis / Q000378:metabolism / Q000473:pathology / Q000821:virology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism; D014162:Transfection; D053773:Transforming Growth Factor beta1 / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects; D054334:Viral Regulatory and Accessory Proteins / Q000235:genetics* / Q000378:metabolism
D000199:Actins; C526317:CCN2 protein, human; D024042:Collagen Type I; D018125:Receptors, Transforming Growth Factor beta; D015534:Trans-Activators; D053773:Transforming Growth Factor beta1; D054334:Viral Regulatory and Accessory Proteins; C057628:hepatitis B virus X protein; D055513:Connective Tissue Growth Factor; D017346:Protein Serine-Threonine Kinases; D000077294:Receptor, Transforming Growth Factor-beta Type II