MicroRNA-21调控乳腺癌对吉西他滨耐药的机制

The underlying mechanism of microRNA-21 in gemcitabine resistant breast cancer cells

背景与目的:以吉西他滨为基础的联合用药在转移性乳腺癌中展示出很好的临床疗效和安全性,但耐药的出现导致治疗失败。MicroRNA是一类非编码小分子RNA,起到类似癌基因或抑癌基因的作用。虽然肿瘤中关于化疗药物耐药的机制报道很多,但microRNA异常表达与耐药之间的关系及机制还不十分清楚。本研究旨在探讨microRNA-21在乳腺癌吉西他滨耐药中的作用及其可能机制。方法:采用低浓度持续诱导MDA-MB-231细胞的方式构建人乳腺癌耐吉西他滨细胞株,药物敏感性差异达10倍以上,继而通过实时荧光定量PCR(real-time PCR,RT-PCR)、CCK-8、蛋白[质]印迹法(Western blot)、转染、划痕和Transwell等实验分别检测microRNA-21对药物的敏感性及上皮-间充质转化(epithelial-mesenchymal transition,EMT)标志物的影响。结果:在乳腺癌吉西他滨耐药细胞株中存在EMT现象,相比亲代细胞,microRNA-21呈高表达,并与吉西他滨敏感性呈负相关。转染microRNA-21的抑制剂和mimic可以分别下调和上调micro RNA-21表达,同时EMT现象和药物敏感性也发生了相应的变化。结论:MicroRNA-21可能通过诱导肿瘤细胞的EMT发生而介导乳腺癌对吉西他滨的耐药。

Background and purpose：Gemcitabine-based chemotherapy has been shown to have signiifcant activity and favourable safety in metastatic breast cancer patients, but the effectiveness is limited due to drug resistance. MicroRNAs are a family of small non-coding RNA molecules, acting as oncogenes or tumor suppressors. Although various mechanisms of chemoresistance have been uncovered, the aberrant microRNA expression and its relationship with drug resistance of breast cancer are still unclear. This study explored the potential role and underlying mechanism of microRNA-21 in gemcitabine resistant breast cancer. Methods：MDA-MB-231 cells were continuously exposed to the increasing concentrations of gemcitabine to induce drug resistance to gemcitabine, which was 10 times more resis-tant. Then multiple methods were used including real-time PCR （RT-PCR）, CCK-8, Western blot, transfection, wound healing and Transwell assay to observe the effect of microRNA-21 on epithelial-mesenchymal transition （EMT） and chemosensitivity. Results：The expression of microRNA-21 was up-regulated in gemcitabine resistant breast cancer cell line and inversely correlated with gemcitabine sensitivity. Manipulation of microRNA-21 status could change microR-NA-21 level, and could result in corresponding changes in EMT status and drug sensitivity. Conclusion：MicroRNA-21 induces gemcitabine resistance possibly via EMT process in breast cancer.