Effects of siRNA-mediated HIF-1α gene silencing on angiogenesis in osteosarcoma

OBJECTIVE To explore angiogenesis in osteosarcoma under the condition of hypoxia-inducible factor (HIF)-1α gene silenced by small interference RNA (siRNA). METHODS The SaOS-2 osteosarcoma cells, transfected with the recombinant plasmid pSilencer2.1-HIF-1α or pSilencer2.1-SCR, were classified as HIF-1α/siRNA group or SCR/siRNA group, respectively. In which, vascular endothelial growth factor (VEGF) immunohistochemistry were performed. HIF-1α and VEGF protein contents were detected by western blot. Gene expressions of HIF-1α 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-1α and VEGF protein contents, and the relative expressions of HIF-1α mRNA and VEGF mRNA in HIF-1α/siRNA group were obviously reduced. In vivo, morphological observation illustrated that heteromorphism were not obvious in the cells of HIF-1α/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-1α/siRNA group, and MVD in HIF-1α/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-1α gene silencing, which is expected to provide a novel and attractive target of therapeutic strategies of osteosarcoma.