Enhanced expression of vascular endothelial growth factor-A in ground glass hepatocytes and its implication in hepatitis B virus hepatocarcinogenesis.
Ground glass hepatocytes (GGH) in chronic hepatitis B virus (HBV) infection harbor HBV pre-S deletion mutants in endoplasmic reticulum (ER) and exhibit complex biologic features such as ER stress, DNA damage, and growth advantage. The presence of pre-S mutants in serum has been shown to predict the development of hepatocellular carcinoma (HCC) in HBV carriers. GGHs hence represent a potentially preneoplastic lesion. Whether a specific growth factor is overexpressed and activated in GGHs remains to be clarified. In this study, growth factor(s) up-regulated by pre-S mutants was identified using a growth factor array in HuH-7 cells. Immunohistochemistry, reverse-transcriptase polymerase chain reaction, and Western blot analysis were performed to study the participation of these genes and their signal pathways in HuH-7 cells and liver tissues. We demonstrate that vascular endothelial growth factor-A (VEGF-A) was up-regulated by pre-S mutants in HuH-7 cells and further confirmed in GGHs by immunostaining. The VEGF-A up-regulation by pre-S mutants could be suppressed by vomitoxin, an ER stress inhibitor. Furthermore, pre-S mutants-expressed HuH-7 cells exhibited activation of Akt/mTOR (mammalian target of rapamycin) signaling and increased growth advantage, which could be inhibited by VEGF-A neutralization. Consistent with this notion, enhanced expression of VEGF-A and activation of Akt/mTOR signaling, comparable to the levels of paired HCC tissues, were also detected in HBV-related nontumorous livers.


CONCLUSIONS
The enhanced expression of VEGF-A in GGHs provides potential mechanism to explain the progression from preneoplastic GGHs to HCC in chronic HBV infection.
Yang
Jui-Chu
JC
Institutes of Basic Medical Sciences, National Cheng Kung University College of Medicine, Tainan, Taiwan.
Teng
Chiao-Fang
CF
Wu
Han-Chieh
HC
Tsai
Hung-Wen
HW
Chuang
Huai-Chia
HC
Tsai
Ting-Fen
TF
Hsu
Yung-Hsiang
YH
Huang
Wenya
W
Wu
Li-Wha
LW
Su
Ih-Jen
IJ
D002460:Cell Line; D002478:Cells, Cultured; D016174:Hepacivirus / Q000472:pathogenicity*; D022781:Hepatocytes / Q000378:metabolism*; D006801:Humans; D008113:Liver Neoplasms / Q000821:virology*; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis*
D042461:Vascular Endothelial Growth Factor A