The Effect Of HIF-1α Expression On Tumor Growth And Apoptosis In MDA-MB-231 Human Breast Cancer Cell Line

Background Hypoxia inducible factor-1(HIF-1)is transactivator in response to hypoxia and its target genes are involved in tumor growth,progression and metastasis.Aim To investigate the effect of HIF-1αprotein expression on tumor growth and apoptosis in human breast cancer cell line MDA-MB- 231 under normoxia.Methods Western Blot was used to evaluate the protein expression of HIF-1αand caspase-3,Bcl-2 and Bax. The protein expression of HIF-αwas bloeked by small interfering RNA.The cells number was counted every other day and drawn the growth curve.Cell cycle was analyzed by Flowcytometric and apoptosis was detected by both Flowcytometric and Hoechst staining method respectively.Results There was basic expression of HIF-1αprotein in human breast cancer cell lines MDA-MB-231,MDA-MB-453,SK-BR-3,T47D and MDA-MB-468 under normoxia with the highest expression in MDA-MB-231 cell line.The cell growth was significantly inhibited and the number of apoptotic cells in the middle or late stage was higher in those ceils with HIF-1αsiRNA than those with random siRNA as detected by both Flowcytometric and Hoechst staining,although the cell cycle was not influenced. The protein expression of activated caspase-3(17Kd)appeared increased much more with the time for serum deprivation elongated in the group with HIF-1αsiRNA than that with random siRNA.But protein expression of Bcl-2 and Bax was not influenced.Conclusion HIF-1αpromotes growth of tumor most probably via inhibition of apoptosis.