Expression of hypoxia inducible factor-1α in HepG2 cells cultured under hypoxia and its relationship with vascularization and apoptosis-related protein

Objective:To investigate the expression of hypoxia inducible factor-1α(HIF-1α) in HepG2 cells cultured under hypoxia for different time periods, and to assess its relationship with vascularization and cell apoptosis. Methods: HepG2 cells were cultured in a medium containing cobalt chloride (125 μmol/L) for different time periods ( 0, 1, 2, 4, 6, and 8 hours ).RT-PCR was used to measure the expression of HIF-1α mRNA,VEGF mRNA,and bcl-2 mRNA, and bax mRNA at the above time points; Western blot was used to determine the expression of Caspase-3 protein and the activity of Caspase-3 enzyme. Results: After 1-2 hour culture under hypoxia, the expression of HIF-1α mRNA,VEGF mRNA,and bcl-2 mRNA began to increase gradually, peaked at 4 h, and then decreased, but were still higher than that before culture. There was no obvious change in the expression of bax mRNA and the ratio of bcl-2 to bax mRNA expression had a similar change with that of bcl-2 mRNA expression. The changes of Caspase-3 protein/mRNA and Caspase-3 enzyme activity were contrary to that of HIF-1α. Conclusion: HIF-1α may inhibit the apoptosis of hepatic cancer cells through regulating the expression of VEGF, bcl-2, bax, and Caspase-3, and the inhibition is related to the severity of hypoxia.