Abstract:

Objective To investigate the effect of inhibiting miR-767-5p on migration， invasion and epithelial-mesenchymal transition（EMT） of breast cancer cells. Methods Breast cancer cells were cultured in vitro， and miR-767-5p inhibitor and inhibitor NC were transfected into breast cancer cells. The cells were divided into three groups： Control group， miR-767-5p inhibitor group and inhibitor-NC group. The effects of miR-767-5p inhibitor on the proliferation， invasion and migration of breast cancer cells were detected by CCK-8 assay， Transwell Migration assay and scratch test. Western blot was used to detect the expression levels of migration related proteins MMP-2 and MMP-9. The dual luciferase reporter gene experiment verifies the targeted binding effect of miR-767-5p and IGF1. RT-qPCR and Western blot experiments were used to detect the expression levels of IGF1 mRNA and protein. Western blot was used to detect the expression level of EMT related proteins. Results CCK-8 assay showed that compared with the control group and inhibitor-NC group， the miR-767-5p inhibitor group significantly inhibited the proliferation of MCF-7 cells（P < 0.05）. Transwell assay showed that the number of invasive cells of breast cancer cells in miR-767-5p inhibitor group was significantly lower than that in control group and inhibitor NC group （P < 0.05）. Scratch test showed that compared with the control group and inhibitor NC group， the migration rate of breast cancer cells in miR-767-5p inhibitor group decreased significantly （P < 0.05）. Luciferase reporter gene assay showed that miR-767-5p targeted IGF1 binding. Western blot showed that compared with the control group and inhibitor NC group， the expression level of E-cadherin protein in the miR-767-5p inhibitor group was significantly increased （P < 0.05）， while the expression levels of N-cadherin， MMP-2， and MMP-9 protein were significantly reduced （P < 0.05）. Compared with the control group and inhibitor-NC group， the mRNA and protein expression levels of IGF1 in the miR-767-5p inhibitor group were significantly reduced （P < 0.05）. Conclusion Suppressing the expression of miR-767-5p may inhibit the proliferation， invasion， migration and EMT of breast cancer cells by down-regulating IGF1.

Key words: breast cancer, miR-767-5p, insulin-like growth factor-1, epithelial-mesenchymal transition, migration and invasion