MicroRNA-126-5p Inhibits the Migration of Breast Cancer Cells by Directly Targeting CNOT7

BACKGROUND: To assess the effect of microRNA-126-5p (miR-126-5p) on the migration of the breast cancer MCF7 cell line. METHODS: GSE143564 was downloaded from the Gene Expression Omnibus (GEO; http://www.ncbi.nlm.nih.gov/geo) to identify the differentially expressed miRNAs between breast cancer and adjacent tissues. Quantitative reverse transcription PCR (RT-qPCR) was used to assess miR-126-5p levels in the normal 184A1 breast cell line and the breast cancer MCF7 cell line. The MCF7 cell line was then transfected with miR-126-5p mimics or corresponding negative control (NC-mimic). The proliferation and migration abilities of the MCF7 cell line were measured by methyl thiazolyl tetrazolium (MTT), Transwell and scratch healing assays. CCR4-NOT transcription complex and subunit 7 (CNOT7) expression levels in the NC-mimic and miR-126-5p mimic groups were measured by Western blot analysis. Bioinformatic analysis and a dual-luciferase reporter assay were performed to identify the miR-126-5p target gene. RESULTS: One hundred forty-eight differentially expressed miRNAs (downregulated = 55, upregulated = 93) were identified. MiR-126-5p expression in the MCF7 cell line was significantly downregulated relative to that of 184A1 cell line (P < 0.05). Compared with that observed in the control and NC-mimic groups, cell proliferation in the miR-126-5p mimic group was significantly decreased at 48 and 72 h posttransfection (P < 0.05). In addition, the scratch healing rate and number of membrane-piercing cells in the miR-126-5p overexpression group were lower than those detected in the control and NC groups (P < 0.05). Furthermore, miR-126-5p could reduce the luciferase activity for the wild-type CNOT7 gene 3’-untranslated region (UTR) reporter (P < 0.05) but had no effect on the mutant 3’UTR reporter (P > 0.05). Compared with that observed in the NC and control groups, the levels of CNOT7 in the miR-126-5p overexpression group decreased (P < 0.05). CONCLUSION: Upregulation of miR-126-5p can inhibit the migration of the breast cancer MCF7 cell line, which may involve its direct targeting of the 3’UTR of CNOT7.