Inhibition of hypoxia-induced angiogenesis by trichostatin A via suppression of HIF-1a activity in human osteosarcoma

J Exp Clin Cancer Res. 2006 Dec;25(4):593-9.

Abstract

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.

MeSH terms

  • Bone Neoplasms / blood supply*
  • Bone Neoplasms / pathology
  • Cell Hypoxia
  • Cell Line, Tumor
  • Enzyme Inhibitors / pharmacology*
  • Humans
  • Hydroxamic Acids / pharmacology*
  • Hypoxia-Inducible Factor 1, alpha Subunit / antagonists & inhibitors*
  • Neovascularization, Pathologic / pathology*
  • Neovascularization, Pathologic / physiopathology
  • Neovascularization, Pathologic / prevention & control*
  • Osteosarcoma / blood supply*
  • Osteosarcoma / genetics
  • Osteosarcoma / pathology
  • Reverse Transcriptase Polymerase Chain Reaction
  • Vascular Endothelial Growth Factor A / biosynthesis

Substances

  • Enzyme Inhibitors
  • HIF1A protein, human
  • Hydroxamic Acids
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Vascular Endothelial Growth Factor A
  • trichostatin A