Effects of ionizing radiation on autophagy and apoptosis in MCF-7 cells with Beclin 1 over-and low-expressions and their regulating mechanisms / 吉林大学学报(医学版)

ABSTRACT

Objective To establish the MCF-7 cell models of Beclin 1 over-and low-expressions,and to detect the autophagic and apoptotic changes after 4 Gy irradiation,and to explore their molecular regulation mechanisms. Methods MCF-7,MCF-7 + 4Gy,MCF-7-Beclin 1 + 4Gy and MCF-7-Belcin 1 RNAi+ 4Gy groups were set up. Molecular biology method was used to construct Beclin 1 over-expression vector pcDNA3.1-Beclin 1,and to estabilish the Beclin 1 over- and low-expression cell models.After the cells were irradiated with 4 Gy, the autopahgic cell percentages were measured by fluorescence microscope with MDC staining, the apoptotic cell percentages were measured by FCM with AnnexinⅤ-FITC and PI staining,and the expressions of Beclin1,P53, Bcl-2 and Bax proteins were measured by Western blotting method.Results Compared with MCF-7 group,the autophagic and apoptotic cell percentages in MCF-7+4 Gy,MCF-7 Beclin 1 +4 Gy and MCF-7-Beclin 1 RNAi+4 Gy groups were significantly increased (P <0.05 or P <0.001 ),especially in MCF-7 Beclin 1+4 Gy group which was significantly higher than those in MCF-7 + 4 Gy (P < 0.05);while there was significant difference in the necrotic cell percentages between various groups. After 4 Gy irradiation, compared with MCF-7 group, the expression levels of Beclin 1,P53 and Bax proteins in MCF-7 + 4 Gy and MCF-7-Beclin 1 + 4 Gy groups were increased,but the expression levels of Bcl-2 protein were decreased,especially in MCF-7-Beclin 1 + 4 Gy group. Conclusion The MCF-7 cell models of Beclin 1 over-and low-expressions are successfully established,and ionizing radiation could induce the autophagy and apoptosis of MCF-7 cells,which is more obvious in Beclin 1 over-expression MCF-7 cells.Beclin 1 can activate P53,inhibit Bcl-2 and activate Bax,which forms the regulation of autophagy and apoptosis by P53 .