Effects of silencing HIF-1 α gene by RNA interference on taxol-induced apoptosis of human esophageal squamous cell line EC9706

Objective: To study the mechanism of hypoxia-induced drug-resistance in esophageal squamous cell carcinoma and observe the effect of hypoxia inducible factor 1 alpha (HIF-1α) on the Taxol-induced apoptosis of EC9706 cells. Methods: Small interference RNA (siRNA) targeting HIF-1α was constructed and transfected into human EC9706 cells. Then EC9706 cells were cultured under chemical hypoxia conditions induced by CoCl₂, a chemical hypoxia inducer. The expression of HIF-1α in EC9706 cells were detected by Western blot before and after RNA interference. The effect of Taxol on apoptosis of EC9706 cells were determined by TUNEL assay and Annexin V/PI double staining. Results: The expression of HIF-1α protein was induced by CoCl₂ 75 μmol/L after 4 h, and was significantly inhibited by siRNA-HIF-1α. The apoptosis rate of EC9706 cells induced by hypoxia were significantly higher in siRNA-HIF-1α transfection group than those without transfection or transfected with control siRNA (P < 0.05). Conclusion: Over-expression of HIF-1α inhibited the apoptosis of EC9706 cells induced by Taxol under hypoxia. siRNA targeting HIF-1α increases the therapeutic efficacy of esophageal squamous cell carcinoma.