Inhibitory effect of HCPT on expression of HIF-1α and downstream genes in hypoxic human cervical SiHa cancer cells

Abstract

The hypoxic model to simulate hypoxic microenvironment in solid tumors was established and the effect of hydrocamptothecin (HCPT) on the hypoxia-induced over-expression of HIF-1alpha and VEGF genes was explored. Human cervical cancer SiHa cells were cultured in vitro under hypoxic conditions (37 degrees C, 5% CO(2), 1% O(2)) and treated with different concentrations of HCPT for 24 h. The mRNA and protein expression levels of HIF-1alpha, VEGF and Glut1 in SiHa cells were detected by semi-quantitative RT-PCR and Western blot respectively. Normoxic control groups were exposed to normoxic conditions for 24 h. Under normoxic conditions, HCPT had no obvious effects on the HIF-1alpha and VEGF gene expression. Hypoxia induced the up-regulation of HIF-1alpha protein and downstream VEGF gene, and HCPT showed a dose-dependently inhibitory effect on the hypoxia-induced over-expression of HIF-1alpha protein and VEGF gene expression in SiHa cells, whereas HCPT had no significant effect on the HIF-1alpha mRNA expression. No difference in HCPT cytotoxicity was observed between hypoxic groups and normoxic control groups. It was suggested that HCPT could inhibit the expression of HIF-1alpha protein and downstream VEGF gene in hypoxic SiHa cells in a dose-dependent manner, and the inhibitory effect was not related with HCPT cytotoxicity.