MiR-34a对乳腺癌Mcf-7／ADR细胞株多柔比星敏感性影响研究

目的：探讨乳腺癌细胞株MCF7和耐药株MCF7／ADR中miR-34a的表达差异及miR-34a对于多柔比星化疗敏感性的影响。方法：采用实时定量PCR技术检测MCF-7细胞及MCF-7／ADR细胞中miR-34a的表达差异。采用转染技术，以脂质体为载体，在MCF_7／ADR细胞株中过表达miR-34a后，检测其对于多柔比星耐药活性的影响，同时采用实时定量PCR技术和蛋白质印迹法技术检测靶基因的表达变化。结果：MCF-7细胞株和耐药株MCF-7／ADR中miR-34a的相对表达量分别为1．01±0．03和0．76±0．04，在耐药细胞株中呈现下调表达，P=0．007。MTT结果显示，MCF7及其耐药株MCF-7／ADR细胞多柔比星半数抑制浓度Ic5。分剐为（0，22±0．02）和（18．7±0．09）ftmol／L。对耐药株MCF-7／ADR过表达miR34a后，MCF-7／ADR细胞对多柔比星的ICso降低为（10．7士0．11）mol／L，明显增强此细胞株对于多柔比星的耐药敏感性。实时定量PCR结果显示，与转染阴性对照RNA相比，于耐药株MCF7／ADR细胞中转染miR--34a后耐药相关靶基因Bcl-2和CCNDl的mRNA水平分别降低了0．46±0．02（P=0．002）和0．33±0．02（P=0．008）。蛋白质印迹结果显示，过表达miR-34a后，可明显下调靶基因Bcl-2和CCNDl的表达。结论：上调表达miR34a可以增加耐药细胞株MCF-7／ADR对于多柔比星的耐药敏感性。

Effect of Mir-34a on sensitivity of breast cancer cells MCF-7/ADR to adriamycin

OBJECTIVE：To evaluate the expression level, of miR-34a and further investigate the potential influence on chemotherapy sensitivity by treating with adriamycin in MCF7 cells and MCR-7/ADR cells. METHODS： Mir-a4a expres- sion level was determined by using Real-time PCR. Synthetic miR-34a was transfected into MCF-7/ADR cells with lipo fectamine 2000 vector. Drug resistance of cells was detected by MTT assay. The target genes expression of miR-34a was e valuating by Real-time PCR and western blot.. RESULTS ： Comparing with MCF-7 cells （1.01±4 0.03）, the expression level of miR-34a in MCF-7/ADR cells was 0.76±0.04 （P=0. 007） and which was lower than that of MCF-7 cells. The ICs0 of ADM in MCF-7 and MCF-7/ADR cells was （0.22±0.02） btmol/L and （18.7±0.09）mot/L,respectively. Up-regulation of miR-34a,the ICs0 value of ADM in MCF-7/ADR cells decreased to （10.7 ±0.11） ptmoI/L. Moreover, compared with NC RNA transfection group,transfeetion of miR-34a could significantly down-regulate the mRNA level of Bcl-2 （values were 0. 46±0. 02,P=0. 002） and CCND1 （values were 0. 33±0. 02,P=0. 008） in MCF-7/ADR cells. Besides,western blot results showed that over-expression of miR-34a could significantly down-regulate the expression of Bcl-2 and CCND1. CONCLUSION： The resistance on ADM of MCF-7/ADR cells is inhibited by miR-34a gene up-regulating.