Effects Of Pentabrominated Diphenyl Ethers On Proliferation And Apoptosis And Mechanism In Breast Cancer MCF-7 Cells

Objective: To study The molecular mechanisms of proliferation and apoptosis in breast cancer lines MCF-7 cells by penta-brominated Diphenyl EthersMethods: Human breast cancer lines MCF-7 cells were grown in DMEM medium . MTT assay was employed to investigate the proliferation of human breast cancer lines MCF-7 cell. The cell cycle of Human breast cancer lines MCF-7 cells was analyzed by flow cytometry(FCM). Immunocytochemistry was performed to determine protein expression of C-Myc and p53 , The transcription of C-Myc gene , p53 gene , Bcl-2 gene and Bax gene were determined by reverse transcription-polymerase chain reaction(RT-PCR). The protein expression of Bcl-2 and Bax was determined by Western blot.Results: Compared with the ethanol control , 1×10-8mol/L,1×10^-7mol/L,1×10^-6mol/L,1×10^-5mol/L,1×10-4mol/L BDE-99 stimulated proliferation in human breast cancer lines MCF-7 cells by MTT assay with a dose-dependent and time-dependent fashion at 48h,72h,96h (P﹤0.01); FCM analyses revealed that treatment with 1×10^-6mol/L,1×10^-5mol/L,1×10-4mol/L BDE-99 for 72h Promoted the G0/G1 phase to S phase and enhance cell proliferation index;Immunocytochemistry analyses revealed that treatment with 1×10-8mol/L,1×10-7mol/L,1×10^-6mol/L,1×10^-5mol/L,1×10-4mol/L BDE-99 for 72h resulted in increased protein expression of C-Myc and inhibited protein expression of p53(P﹤0.01); RT-PCR analyses revealed that treatment with 1×10-8mol/L,1×10-7mol/L,1×10^-6mol/L,1×10^-5mol/L,1×10-4mol/L BDE-99 for 72h resulted in increased mRNA expression of C-Myc and Bcl-2 and inhibited mRNA expression of p53 and Bax(P﹤0.01); Western blot analyses revealed that treatment with 1×10-8mol/L,1×10-7mol/L,1×10^-6mol/L,1×10^-5mol/L,1×10-4mol/L BDE-99 for 72h resulted in increased protein expression of Bcl-2 and inhibited protein expression of Bax with a dose-dependent fashion.Conclusions: BDE-99 possessed estrogenic activity and could markedly stimulate proliferation in estrogen responsive breast cancer MCF-7 cells. Up-regulation of C-Myc,Bcl-2 mRNA and protein expression was suggested to be involved in this biological effect. p53,C-Myc,Bax,Bcl-2 pathway might be involved in cell proliferation and apoptosis events regulated by BDE-99 in breast cancer MCF-7 cells.