Objective: To investigate the effects of miR-671-3p on the proliferation and invasion of breast cancer cells and explore the possible mechanism.
Methods: We examined the expressions of miR-671-3p in human normal epithelial cells (MCF-10A) and breast cancer cell lines (MCF-7, MDA-MB-231, and SK-BR3) using RT-PCR. The effects of transfection with a miR-671-3p mimic or inhibitor on the proliferation, migration and invasion of MCF-7 cells were evaluated using CCK-8 assay and Transwell chamber assay. The target gene of miR-671-3p was predicated with Targetscan and validated by a dual luciferase reporter system and Western blotting.
Results: The expression of miR-671-3p was significantly lower in breast cancer cells than in normal breast epithelial cells. Compared with negative control group, MCF-7 cells with miR-671-3p overexpression exhibited significantly reduced proliferation and invasion, whereas inhibition of miR-671-3p obviously promoted the cell proliferation and invasion. Luciferase reporter assay demonstrated that DEPTOR was the target gene of miR-671-3p, and miR-671-3p overexpression caused significant down-regulation of the protein expression of DEPTOR.
Conclusions: MiR-671-3p suppresses the proliferation and invasion of breast cancer cell line MCF-7 by directly targeting DEPTOR protein.
目的: 研究miR-671-3p对乳腺癌细胞增殖、侵袭生物学功能的影响及其可能的作用机制。
方法: 以实时荧光定量PCR方法检测正常乳腺上皮细胞（MCF-10A）与乳腺癌细胞（MCF-7、MDA-MB-231、SK-BR3）中miR-671-3p表达情况；检测miR-671-3p在MCF-7细胞中的转染效率；通过CCK-8法检测miR-671-3p对MCF-7细胞增殖的影响；通过Transwell实验、划痕实验检测miR-671-3p对MCF-7细胞侵袭迁移能力的影响；Targetscan预测miR-671-3p的靶基因，并通过双荧光素酶法和Western blot法对靶基因DEPTOR进行验证，并检测DEPTOR的表达。
结果: miR-671-3p在乳腺癌细胞系MCF-7、MDA-MB-231、SK-BR3的表达量低于乳腺正常上皮细胞MCF-10A的表达。通过mimics、inhibitor分别促进、抑制miR-671-3p在MCF-7细胞中的表达后，结果显示miR-671-3p对乳腺癌细胞的增殖有抑制作用（P < 0.05），对肿瘤细胞的侵袭和迁移有抑制作用（P < 0.05）。双荧光素酶结果显示DEPTOR蛋白为miR-671-3p的直接作用靶点，过表达miR-671-3p可直接抑制DEPTOR蛋白的表达。
结论: miR-671-3p直接靶向作用于DEPTOR蛋白从而抑制乳腺癌细胞的增殖和侵袭。
Keywords: DEPTOR; breast cancer; cell proliferation; miR-671-3p; neoplasm invasiveness.