miR-6775-3p在乳腺癌细胞中的表达及其对乳腺癌细胞生物学行为的影响

背景与目的：微小RNA（microRNA，miRNA）与肿瘤的发生、发展过程密切相关。探讨miR-6775-3p在乳腺癌细胞系中的表达及其对乳腺癌细胞生物学行为的影响。方法：通过实时荧光定量聚合酶链反应（real-time fluorescence quantitative polymerase chain reaction，RTFQ-PCR）检测4种乳腺癌细胞系MDA-MB-231、MDA-MB-453、MDA-MB-468和BT-549中miR-6775-3p的表达水平，选取miR-6775-3p表达水平最低的乳腺癌细胞系过表达miR-6775-3p后，采用细胞计数试剂盒（cell counting kit-8，CCK-8）法检测细胞的增殖情况，同时采用transwell迁移和侵袭实验分别检测细胞迁移和侵袭能力的变化。通过RTFQ-PCR和蛋白［质］印迹法（Western blot）检测miR-6775-3p过表达的乳腺癌细胞系中细胞周期蛋白依赖性蛋白激酶4（cyclin-dependent protein kinase 4，CDK4）和CDK6，以及侵袭转移标志物基质金属蛋白酶（matrix metalloproteinase，MMP）17和MMP24 mRNA以及蛋白的表达变化。结果：RTFQ-PCR结果显示，乳腺癌细胞系MDA-MB-453中miR-6775-3p的表达最低，在MDA-MB-453细胞中转染miR-6775-3p mimics后，miR-6775-3p的表达水平明显升高（P<0.001）。CCK-8实验结果显示，MDA-MB-453细胞过表达miR-6775-3p后，细胞的增殖能力明显降低（P<0.01）。Transwell迁移和侵袭实验结果显示，MDA-MB-453细胞过表达miR-6775-3p后，细胞的迁移（P<0.001）和侵袭能力（P<0.01）明显降低。RTFQ-PCR和Western blot实验结果显示，CDK4、CDK6及MMP17、MMP24的mRNA表达和蛋白水平均显著降低（P<0.01）。结论：miR-6775-3p可能抑制乳腺癌细胞的增殖、迁移和侵袭能力。

Expression of miR-6775-3p in breast cancer cells and its effect on biological behavior of breast cancer cells

Background and purpose: MicroRNA (miRNA) is closely related to the occurrence and development of tumors. This study aimed to investigate the expression of miR-6775-3p in breast cancer cells and its effect on the biological characteristics of breast cancer cells. Methods: Real-time fluorescence quantitative polymerase chain reaction (RTFQ-PCR) was used to detect the expression level of miR-6775-3p in four breast cancer cell lines MDA-MB-231, MDA-MB-453, MDA-MB-468 and BT-549. After miR-6775-3p was over-expressed in breast cancer cells with the lowest expression level of miR-6775-3p, the proliferation ofcells was detected by cell counting kit-8 (CCK-8) assay, and the migration and invasion ability of cells were detected by transwell migration and invasion assay. To further explore the molecular mechanism of miR-6775-3p in breast cancer, the expressions of cyclin-dependent protein kinase 4 (CDK4), CDK6 and invasion and metastasis markers matrix metalloproteinase 17 (MMP17) and MMP24 in miR-6775-3p overexpressing breast cancer cells were detected by RTFQ-PCR and Western blot. Results: RTFQ-PCR results showed that the expression of miR-6775-3p was the lowest in breast cancer cell line MDA-MB-453, and the expression level of miR-6775-3p was significantly increased after transfection of miR-6775-3p mimics in MDA-MB-453 cells (P<0.001). CCK-8 assay results showed that the cell proliferation activity was significantly decreased after miR-6775-3p was overexpressed in MDA-MB-453 cells (P<0.01). Transwell migration and invasion assay results showed that the cell migration (P<0.001) and invasion abilities (P<0.01) were significantly decreased after miR-6775-3p was over-expressed in MDA-MB-453 cells. RTFQ-PCR and Western blot results showed that the expressions of cyclin-dependent protein kinases CDK4 and CDK6, as well as the mRNA and protein levels of cell invasion and metastasis markers MMP17 and MMP24 were significantly decreased (P<0.01). Conclusion: miR-6775-3p may inhibit the proliferation, migration and invasion of breast cancer cells.