Vascular endothelial growth factor protects hepatoma cells against oxidative stress-induced cell death.
BACKGROUND
The aim of the present study was to examine coordination of the vascular endothelial growth factor (VEGF) and VEGF receptor (Flk-1) system and to study control of VEGF expression by oxidative stress, which is considered a model for chronic liver disease.


METHODS
Cell viability was determined by test method with 3-[4, 5-dimethylthiazol-2-yl]-2, 5-dephenyl tetrazolium bromide (MTT). Expressions of cellular proteins were evaluated by western blot analysis.


RESULTS
The c-Met tyrosine phosphorylation in PLC/PRF/5 hepatoma cells was increased by treatment with 20 ng/mL hepatocyte growth factor (HGF), and extracellular signal-regulated kinase (ERK) was also activated. Although Flk-1 was phosphorylated in response to VEGF (>50 ng/mL), phosphorylated ERK was not detected at these concentrations. A total of 5.0 and 10 micromol/L hydrogen peroxide (H(2)O(2)) caused cell death in a dose-dependent manner after 24 h. On western blot analysis at 1 h with H(2)O(2), rapid phosphorylation of both ERK1/2 and c-Jun NH(2)-terminal kinase (JNK) was observed. In the first 6 h, H(2)O(2) induced cell death for 58.4 +/- 6.8%, whereas the presence of 100 ng/mL VEGF improved the survival rate to 77.2 +/- 4.2%. The VEGF significantly decreased H(2)O(2)-induced cell death after 12 h, whereas HGF (20 ng/mL) did not have a similar effect. When cells were incubated with 5 micromol/L H(2)O(2), expression of VEGF protein was detected. Furthermore, H(2)O(2)-induced phosphorylation of ERK and JNK was also reduced by VEGF (100 ng/mL). In contrast, HGF did not induce phosphorylation of ERK and JNK.


CONCLUSIONS
Hepatoma cells might be able to survive under continuous oxidative stress through expression of VEGF.
Osada
Shinji
S
Surgical Oncology, Gifu University School of Medicine, 1-1 Yanagido, Gifu City 501-1194, Japan. sting@cc.gifu-u.ac.jp
Imai
Hisashi
H
Tomita
Hiroyuki
H
Tokuyma
Yasuharu
Y
Okumura
Naoki
N
Sakashita
Fumio
F
Nonoka
Kenichi
K
Sugiyama
Yasuyuki
Y
D006528:Carcinoma, Hepatocellular / Q000378:metabolism*; D016923:Cell Death; D017228:Hepatocyte Growth Factor / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000633:toxicity; D008113:Liver Neoplasms / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008954:Models, Biological; D018384:Oxidative Stress / Q000187:drug effects; D010766:Phosphorylation; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism; D014407:Tumor Cells, Cultured; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism* / Q000494:pharmacology; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism*
D042461:Vascular Endothelial Growth Factor A; D017228:Hepatocyte Growth Factor; D006861:Hydrogen Peroxide; D019859:Proto-Oncogene Proteins c-met; D040301:Vascular Endothelial Growth Factor Receptor-2; D020928:Mitogen-Activated Protein Kinases