格列美脲通过下调miRNA-34a表达抑制人乳腺癌细胞MCF-7增殖的作用研究

Inhibitory Effect of Glimepiride on the Proliferation of Human Breast Cancer Cell Line MCF-7 by Down-regulating the Expression of MicroRNA-34a

目的:研究微小RNA-34(microRNA-34,miRNA-34a)在格列美脲抑制人乳腺癌细胞MCF-7增殖过程中的作用机制。方法:体外培养人乳腺癌细胞MCF-7,用不同剂量(500,1 000,2 000 nmol·L-1)格列美脲染毒48 h后,采用MTT法测定格列美脲对人乳腺癌细胞MCF-7细胞增殖的影响,RT-PCR检测miRNA-34a、Bax、Bcl-2和caspase-3 mRNA的相对表达量,流式细胞术检测人乳腺癌细胞MCF-7的细胞凋亡率。结果:随着格列美脲剂量的增加,人乳腺癌细胞MCF-7增殖率和miRNA-34a mRNA水平显著降低,caspase-3 mRNA、Bax、Bcl-2、Bax/Bcl-2水平和细胞凋亡率显著升高,与空白组比较差异有统计学意义(P<0.05);且剂量-效应关系明显(P<0.05)。结论:格列美脲对人乳腺癌细胞MCF-7增殖具有抑制作用,其机制可能是通过调低miRNA-34a的表达水平,促进Bax、Bcl-2和caspase-3高表达,启动了细胞凋亡程序,导致了人乳腺癌细胞MCF-7细胞凋亡。

Objective: To study the mechanism of microRNA-34( microRNA-34 and microRNA-34 a) in inhibiting the proliferation of human breast cancer cell line MCF-7 by glimepiride. Methods: Human breast cancer cell line MCF-7 was cultured in vitro and treated with different doses( 500,1000,2000 nmol·L^-1) of glimepiride for 48 h. The effect of glimepiride on the proliferation of MCF-7 cells was determined by MTT assay,the relative mRNA expressions of miRNA-34 a,Bax,Bcl-2 and caspase-3 were detected by RTPCR,and the apoptosis rate of MCF-7 cells was detected by flow cytometry. Results: With the increase of glimepiride dosage,the proliferation rate of MCF-7 and the level of microRNA-34 a in human breast cancer cells decreased significantly,while the levels of caspase-3,Bax, Bcl-2 and Bax/Bcl-2 and the apoptotic rate increased significantly, there was significant difference between glimepiride groups and the blank group( P < 0. 05),and the dose-effect relationship was significant( P < 0. 05). Conclusion:Glimepiride inhibits the proliferation of human breast cancer cell line MCF-7. The mechanism may be related to reducing the expression level of miRNA-34 a,promoting the high expressions of Bax,Bcl-2 and caspase-3,and initiating the apoptosis program,which causes the apoptosis of human breast cancer cell MCF-7 cells.