Decreased miR-124-3p Expression Prompted Breast Cancer Cell Progression Mainly by Targeting Beclin-1.

Abstract

Recent findings have revealed that abnormal expression of microRNAs (miRNA, miR) contributes to the malignancies of various cancers. Here, we report a novel miRNA that regulates the expression of Beclin-1 in breast cancer cells. The expression of miR-124-3p and Beclin-1 was identified in breast cancer tissues and breast cancer cell lines. To explore whether Beclin-1 was the target gene of miR-124-3p, luciferase reporter assay was applied. MIR-124-3p was overexpressed or inhibited with the corresponding mimics or inhibitors. The expression of autophagy-related proteins including Beclin-1 and LC3II were explored by western blot and quantitative real-time PCR. We first demonstrated that miR-124-3p was decreased in breast cancer tissues and breast cancer cells lines. Furthermore, we validated that miR-124-3p could negatively regulate the expression of Beclin-1. Increased miR-124-3p significantly decreased the expression of Beclin-1 and LC3I. Further study showed that overexpres- sion of miR-124-3p could partially reverse 4-hydroxytamoxifen (4-OHT)-induced autophagy in breast cancer cells. Decreased miR-124-3p expression prompted breast cancer cell progression mainly by enhancing the expression of autophagy related protein, Beclin-1.