ABSTRACT
Abstract Objective: MicroRNAs play crucial roles in the pathogenesis of cancers. MiRNA-218-5p may act as either an oncogene or a tumor suppressor, but its role in the pathogenesis of Breast Cancer (BC) remains unclear. Methods: Infiltrative breast ductal carcinoma as well as corresponding adjacent normal samples were collected from 30 patients. Mimics and inhibitors of miRNA-218-5p or corresponding negative controls were transfected into BC cells. miRNA-218-5p expression was detected by quantitative PCR. The effects of miRNA-218-5p on the malignant behaviors of BC were assessed. Dual-luciferase reporter assay was employed to evaluate the binding of miRNA-218-5p to LRIG1. Results: BC tissues showed higher miRNA-218-5p expression as compared to the adjacent normal tissues. Ectopic miRNA-218-5p expression accelerated the cell cycle, cell growth and migration of BC, while repressed cell apoptosis. Interestingly, ectopic miRNA-218-5p expression down-regulated LRIG1 expression, and miRNA-218-5p could bind to LRIG1. Also, our study indicated that miRNA-218-5p up-regulated ErbB2 and EGFR expression by targeting LRIG1, suggesting that the LRIG1-mediated signaling pathway contributed to the pro-tumor effects of miRNA-218-5p on BC. Conclusion: MiRNA-218-5p up-regulates ErbB2 and EGFR expression by suppressing LRIG1 expression, thus promoting the malignant behaviors of BC. miRNA-218-5p may exert a pro-tumor effect on BC and serve as a therapeutic target for BC treatment.