Inhibition of hypoxia-induced angiogenesis by trichostatin A via suppression of HIF-1a activity in human osteosarcoma.
The purpose of this study is to determine whether trichostatin A (TSA), a HDAC specific inhibitor, inhibited the induction and functional activity of hypoxia-inducible factor-1 a(HIF-1a) and hypoxia-induced angiogenesis in vitro in human osteosarcoma. The relationship between expression of HIF-1a proteion and angiogenesis in tumor specimens was also studied. Hypoxic regulation of VEGF was studied by RT-PCR, western blotting analysis and enzyme linked immunosorbent assay. The expression of HIF-la and VEGF in human osteosarcoma specimens was studied by immunohistochemical analysis. Under hypoxia, no regulation of HIF-1a mRNA expression was found. However, HIF-1a protein levels increased dramatically in response to hypoxia. Hypoxia increased VEGF mRNA level, but it was significantly inhibited by trichostatin A in a time- and dose-dependent manner (p < 0.05). Strongly positive immunostaining for HIF-1a and VEGF were detectable in the nuclear and cytoplasm of osteosarcoma cells. HIF-1a expressing cells were prominent in areas with high MVD. Significant correlation were found between HIF-1a expression and MVD (p = 0.005, r = 0.767), as well as between VEGF and MVD (p < 0.002, r = 0.701) by Spearman's rank coefficient analysis. These results indicated that HIF-1a is a key factor responsible for angiogenesis by the induction of VEGF. TSA downregulates hypoxia-response genes and hypoxia-induced angiogenesis by the suppression of HIF-1a activity.
Yang
Q C
QC
Department of Orthopeadics, Shanghai Sixth People's Hospital, Shanghai JiaoTong University, Shanghai, China.
Zeng
B F
BF
Shi
Z M
ZM
Dong
Y
Y
Jiang
Z M
ZM
Huang
J
J
Lv
Y M
YM
Yang
C X
CX
Liu
Y W
YW
D001859:Bone Neoplasms / Q000098:blood supply* / Q000473:pathology; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000037:antagonists & inhibitors*; D009389:Neovascularization, Pathologic / Q000473:pathology* / Q000503:physiopathology / Q000517:prevention & control*; D012516:Osteosarcoma / Q000098:blood supply* / Q000235:genetics / Q000473:pathology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis
D004791:Enzyme Inhibitors; C497442:HIF1A protein, human; D006877:Hydroxamic Acids; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D042461:Vascular Endothelial Growth Factor A; C012589:trichostatin A