The Expression Of The Hypoxia Inducible Factor 1α In Breast Cancer And Sensitizing Effect On Anti-tumor Drugs

Objects:To study the expression of HIF-1α,GLUT1 and the relationship with clinical features in the breast cancer.To study the expression of HIF-1αin breast cancer cell lines in hypoxia and normoxia,the change of sensitivity to chemotherapeutic agents of T47D cell after HIF-1αsilencing in hypoxia and mechanisms and the cell proliferation of T47D after HIF-1αsilencing in vivo.Methods:The expression of HIF-1αand GLUT1 in tumor tissues and fibroadenoma were detected by immunohistochemistry technique in tissue of invasive ductal breast cancer and fibroadenoma.The expression of HIF-1αin MCF-7 and T47D was detected by RT-PCR and Western blot.The expression plasmid pGenesil-HIF was transfected into human breast cancer cell line T47D through lipofectamine2000^TM transfection reagent.Cells stably expressing shRNA were screened with G418.The expression of HIF-1αwas detected by RT-PCR and Western blot.T47D Cells transfected with shRNA plasmid were exposed to 150μmol/L Cocl₂ for 48 hours. Different dosages of chemotherapy agents(paclitaxel and epirubicin)added into T47D cells after shRNA transfected.The growth inhibition rates were measured by MTT,cell cycle was measured by flow cytometry and the expression of P-gp and GLUT1 was detected by Western blot and Real-time PCR.The tumor volumes and weights were measured in subcutaneous xeno-graft models.The expression of HIF-1α,GLUT1 and P-gp were detected by IHC.ResultsHIF-1αand GLUT1 was expressed in 34 of 60 cases(56.7%)and 38 of 60 cases (63.3%)in breast cancer especially.In contrast,no expression of HIF-1αand GLUT1 in fibro-adenoma.Expression of HIF-1αand GLUT1 had no relationship with ages,ER,PR and tumor sizes,but with the number of the lymph node,(P＜0.05). Western blot showed significantly increased HIF-1αprotein expression in MCF7 and T47D cells as a result of hypoxia.RT-PCR and Western blot indicated that the HIF-1αmRNA and protein were significantly depressed after the cell being transfected with the shRNA.Paclitaxel and epirubicn cause a greater increase of inhibition in the experimental group than in control.GLUT1 and P-gp protein expression in the experimental group was markly down-regulated compared with the control.Cell cycle analysis showed that the ratio of G0/G1 stage cell was decreased.No difference of these measurements was observed in cells cultured in normal oxygen concentration. The growth rates and tumor weights of HIF-1α-knockdown tumors were drastically in subcutaneous xeno-graft models,which were accompanied by reduced expression of glucose transporter protein 1 in tissue sections.Conclusions:Glycolysis is an important way to gain energy for tumor cell,especially in hypoxia.HIF-1αcould bind the site of target gene,enhance the glycosis and transportation of glucose.Inhibition HIF-1αcould enhance the effect of chemotherapy via inhibition the glycosis and transportation of glucose Our results provide further evidence that HIF-1 might be an effective molecular target for breast cancer therapy.A combination of anti-HIF-1 strategy and traditional chemotherapy may be expected to render more favorable outcomes.