中文摘要：

目的探讨miR-99a对乳腺癌细胞侵袭及迁移的影响，并初步分析其影响乳腺癌细胞侵袭及迁移的可能分子机制。方法利用荧光实时定量PCR检测乳腺癌细胞系MDA—MB-231和MCF-7中miR-99a的表达。运用脂质体介导的转染方法分别将miR-99a模拟物（miR-99amimics）、miR-99a抑制物（miR-99ainhibitors）以及相应对照miRNA转染MDA—MB-231和MCF-7细胞，通过Transwell侵袭实验检测细胞的侵袭力；采用Transwell迁移实验及划痕实验检测细胞的迁移能力；利用生物信息学方法预测miR-99a的靶基因，并对靶基因进行验证。结果（1】高转移潜能的MDA—MB-231细胞中miR-99a表达明显低于低转移潜能的MCF-7细胞，划痕实验中转染miR-99amimics的与转染controlmimics的MDA—MB-231细胞比较迁移能力显著减弱（P〈O．05），而MCF-7细胞转染miR-99ainhibitors后迁移能力明显增强（P〈O．01）。（2）Transwell的侵袭及迁移实验显示，转染miR-99amimics后MDA—MB-231细胞的侵袭和迁移能力明显减弱（P〈O．01）；MCF-7细胞转染miR-99ainhibitors后迁移能力增强（P〈O．01），而侵袭能力基本不变（P〉O．05）。（3）生物信息学方法预测微管相关蛋白（MTMR3）是miR-99a的靶点，实时定量PCR和3’UTR荧光素酶报告基因实验验证了该靶点。（4）干扰了MTMR3后MDA—MB-231细胞的迁移和侵袭能力明显减弱。结论（1）miR-99a对乳腺癌细胞的侵袭及迁移发挥负向调控作用。（2）miR-99a可能通过靶向于MTMR3发挥其对乳腺癌细胞迁移和侵袭的调控作用。

英文摘要：

Objective To investigate the effect of miR-99a on invasion and migration potential of human breast cancer cells and its possible mechanism, Methods The expression level of miR-99a was detected in human breast cancer cell lines MDA-MB-231 and MCF-7 by qRT-PCR. Human breast cancer MDA-MB-231 cells were transfected with miR-99a mimics and control mimics by Lipofectamine. Cell invasion potential was evaluated by Transwell invasion assay; cell migration was detected by Transwell migration assay and wound healing assay. The possible target genes of miR-99a were forecasted by bioinformatics tools and the reliability of these genes was analyzed. Results Remarkable inhibition of cell migration was detected in MDA-MB-231 cells transfected with miR-99a mimics by wound healing and Transwell migration assay, compared to cells transfected with control mimics. MCF-7 cells transfected with miR-99a inhibitors showed increased migration, compared to cells transfected with control inhibitors. Transfection of miR-99a mimics into MDA-MB-231 cells led to a significant decrease in cell invasion as detected by Transwell invasion assay. Myotubularin related protein 3 （MTMR3） was forecasted by bioinformatics tools as a target of miR-99a, which was verified by RT-qPCR and 3＇UTR luciferase reporter assays. Knock down of MTMR3 in MDA-MB-231cells inhibited cell migration and invasion, Conclusion miR-99a negatively may regulate the invasion and migration potential of human breast cancer cells through targeting MTMR3.