Effects of siRNA-mediated HIF-lα gene silencing on angiogenesis in osteosarcoma

Objective: To explore angiogenesis in osteosarcoma under the condition of hypoxia-inducible factor (HIF)-1 alpha gene silenced by small interference RNA (siRNA). Methods: The SaOS-2 osteosarcoma cells, transfected with the recombinant plasmid pSilencer2.1-HIF-1 alpha or pSilencer2.1-SCR, were classified as HIF-1 alpha/siRNA group or SCR/siRNA group, respectively. In which, vascular endothelial growth factor (VEGF) immunohistochemistry were performed. HIF-1 alpha and VEGF protein contents were detected by western blot. Gene expressions of HIF-l alpha and VEGF were quantified by qPCR. Then the transfected SaOS-2 cells were inoculated in nude mice and transplantation tumor were checked via HE staining, VEGF and CD34 immunohistochemistry, and calculation of microvascular density (MVD). Results: In vitro, VEGF immunohistochemistry stains, HIF-1 alpha and VEGF protein contents, and the relative expressions of HIF-1 alpha mRNA and VEGF mRNA in HIF-1 alpha/siRNA group were obviously reduced. In vivo, morphological observation illustrated that heteromorphism were not obvious in the cells of HIF-1 alpha/siRNA group and vascular systems were sparse in its transplantation tumor tissue, and immunohistochemistry revealed that both VEGF and CD34 stains were significantly decreased in HIF-1 alpha/siRNA group, and MVD in HIF-1 alpha/siRNA group (7.3 +/- 1.1) were obviously less than that in SCR/siRNA group (17.2 +/- 3.2) (P<0.05). Conclusion: Angiogenesis in osteosarcoma can be inhibited by siRNA-mediated HIF-1 alpha gene silencing, which is expected to provide a novel and attractive target of therapeutic strategies of osteosarcoma.