Effects of hypoxia on proliferation and apoptosis of osteosarcoma cells

Abstract

Background: Hypoxia can happen during solid tumor growth including osteosarcoma. This study investigated the relationship of hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) on osteosarcoma cell growth and apoptosis under hypoxic conditions. Materials and Methods: Human osteosarcoma cells were cultured under normal or hypoxic conditions. Inhibitors of HIF-1α and VEGF were applied to the cells separately or in combination to block the respective proteins. Cell proliferation and apoptosis were examined by MTT and TUNEL assays, and real-time PCR and ELISA were performed for mRNA and protein expression. Results: There was a dramatic decrease of cell proliferation and an elevation of apoptosis under hypoxia. Blockage of HIF-1α and VEGFR enhanced the cell growth retardation and promoted apoptotic changes. Moreover, blockage of HIF-1α significantly eliminated the expression of VEGF in the cell culture media, and vice versa. Conclusion: HIF-1α and VEGF work closely in regulating osteosarcoma cell growth under hypoxic conditions and blockage of either of them may subsequently influence the presence of the other.