Attenuation of the cytoprotection induced by hypoxic preconditioning upon transfection with BNIP3-siRNA in human neuroblastoma SH-SY5Y cells

Purpose The aim of this study was to investigate the functional role of hypoxic preconditioning (HPC) in human neuroblastoma cells. Methods BNIP3 small-interfering RNA (BNIP3-siRNA) sequence was synthesized and used to transfect human neuroblastoma SH-SY5Y cell lines. Thereafter, BNIP3 expression at mRNA and protein levels and its effects on the cell proliferation were analyzed. The most effective pair of siRNA was selected to knockdown the expression level of BNIP3. Moreover, the effects of HPC on oxygen-glucose deprivation/reperfusion (OGD/R)-induced apoptosis and autophagy in SH-SY5Y cells were explored to further reveal the possible mechanisms underlying HPC. Results BNIP3-siRNA attenuated the protective effects of HPC by decreasing the cell viability, increasing the enzymatic activity of caspase-3 and 9, increasing the rate of apoptosis, and increasing the protein expression level of activated caspase-3. Additionally, BNIP3-siRNA had no significant influence on the expression level of HIF-1 alpha induced by HPC, while it substantially inhibited HPC-induced BNIP3/Beclin1 and autophagy. Conclusions HPC promoted autophagy through regulating BNIP3 to reduce OGD/R.