中文摘要：

目的筛选雌激素受体阴性（ER-）雄激素受体阳性（AR＋）乳腺癌细胞中AR相关的微小RNA（miRNA），并研究其细胞功能学。方法选择MDA—MB-453乳腺癌细胞，雄激素二氢睾酮作用后miRNA芯片杂交筛选出明显上调的miRNA，对其中的let-7a采用实时定量逆转录-聚合酶链反应（RT—qPCR）进行验证；通过转染let-7a特异性反义寡核苷酸使let-7a下调4倍，通过构建质粒和细胞转染实验使let-7a上调〉8倍；噻唑蓝（MTT）和流式细胞术检测转染后细胞增殖和细胞周期的变化。结果miRNA芯片筛选出明显上调的miRNA只有let-7a、b、c、d4个，RT—qPCR结果显示1et-7a上调近13倍；细胞转染后，在let-7a低表达组，MTT检测结果显示，细胞增殖活性增高，至第4天之后与对照组比较差异有统计学意义（P〈0．05），流式细胞术检测结果显示对照组和实验组细胞G，期分别为（72．30±3．16）％和（63．24±3．63）％，S期分别为（19．12±4．45）％和（31．00±4．56）％，G，期细胞比例减少，S期细胞比例增加，差异有统计学意义（P〈0．05），在let-7a高表达组，则出现相反的结果。结论let-7a能够抑制ER—AR＋乳腺癌细胞增殖、使细胞周期阻滞在G1-S期，可能在雄激素抑制ER-AR＋乳腺癌细胞生长过程中发挥主要作用。

英文摘要：

Objective To screen the androgen receptor-related microRNA （miRNA） in estrogen receptor negative but androgen receptor positive （ER - AR ＋ ） MDA-MB-453 breast cancer cell line and study the function. Methods The MDA-MB-453 breast cancer cells were cultured in vitro, and treated with dihydrotestosterone （DHT）. MiRNA array hybridization technique was used to screen the differentially expressed miRNAs. The significantly up-regulated miRNA, let-Ta was selected and checked by using real- time quantitative reverse transcriptase polymerase chain reaction （RT-qPCR）. The MDA-MB-453 cells were transiently transfected with specific antisense oligonucleotide or vector. Cell proliferation was deter- mined by MTr assay and cell cycle was analyzed by flow cytometry ＇after transfection. Results Let-7a was significantly up-regulated in DHT-treated cells as compared with control group. After the cells was trans- fected with oligonucleotide or vector, cells proliferation was inhibited （P 〈 0. 05 ） , and the number of ceils in the G1 phase was significantly increased [ （72. 30 ±3. 16）% vs （63.24±3.63）% ] and that in S phase was significantly decreased [ （ 19. 12 ± 4. 45 ） % vs （ 31.00± 4. 56 ） % ] in let-7a-overexpressed group （P 〈0. 05）. Meanwhile, in let-7a-blocked group, there were the opposite results. Conclusion Let-7a may play an important role in the process of DHT inhibiting ER-AR ＋ breast cancer growth probably by in- hibiting the cell proliferation and causing cell cycle arrest at the G1-S phases.