Abstract
MicroRNAs (miRNAs) are a class of small non-coding RNAs with a length of 21-25 nucleotides and play an essential role in the regulation of cancer initiation, development and progression. Breast cancer (BC) is the most commonly detected malignancy in women and one of the leading causes of death worldwide. In this study, the effects of transfection of microRNA-451a-5p and miR-34a-5p (tumor suppressors), individually and in combination on apoptosis, proliferation and migration of breast cancer cells in vitro were investigated. For this study, malignant breast cancer cells (MDA-MB-231) were transfected with the miR-451a-5p and miR-34a-5p mimics. Subsequently cytotoxicity, apoptosis, proliferation, migration protein and gene expression of caspase-3, caspase-8, MMP9, ROCK, vimentin and c-Myc of the cancer cells were analyzed by MTT, flow cytometry, q-RT-PCR (expression level of caspase-3, caspase-8, MMP9, ROCK, vimentin and c-Myc genes), wound healing and Western blot assays. The results showed that miR-34a-5p and miR-451a-5p could additionally induce apoptosis and cell cycle arrest in the sub-G1phase, suppress proliferation and migration in breast cancer cells, and also decrease the expression of β- catenin and ERK/P-ERK proteins . The present data document that restoration of the tumor suppressor miR-451/miR-34 strongly induces programmed cell death in vitro and apparently inhibits cell proliferation and migration in human breast cancer cells. In summary, miR-451a and miR-34a play an important role in breast cancer cell proliferation and migration via the Wnt/β-catenin and ERK/P-ERK signaling pathways. Therefore, the simultaneous restoration of the presented tumor suppressor miRNAs can be proposed as a valuable and potential therapeutic strategy in the treatment of breast cancer. However, further studies should be useful.