The Effect of miR-34a-5p and miR-145-5p Ectopic Expression on Cell Proliferation and Target Gene Expression in the MDA-MB-231 Cell Line

Abstract

Aim: It was aimed to investigate the effect of miR-34a-5p and miR-145-5p on breast cancer cell line MDA-MB-231 and to determine the expressionof target genes of these microRNAs (miRNAs).Materials and Methods: Firstly, literature search and in silico analysis were performed to detect possible target genes of miR-34a-5p and miR-145-5p, which are known to be tumor suppressors. Mimic miR-34a-5p and miR-145-5p were transfected to the breast cancer cell line MDA-MB-231.Deregulated genes were investigated by the quantitative real-time polymerase chain reaction compared to control cells. Also, the effect of thesemiRNAs on proliferation was determined using the Water Soluble Tetrazolium Salt-8 method. Finally, the expressions of epithelial mesenchymaltransition (EMT) markers, which are known to be important in the metastatic process, are examined.Results: The proliferation of the miR-34a-5p or miR-145-5p transfected cells decreased compared to the control groups. The expression of E2Ftranscription factor 1 (E2F1) (p=0.009), mitogen activated protein kinase 1 (MEK1) (p=0.001) and cyclin dependent kinase 4 (CDK4) (p=0.005)genes, which were among the genes targeted by miR-34a-5p, were significantly reduced. EMT markers were significantly changed in miR-34a-5ptransfected cells (E-Cad increase p=0.01; Vimentin decrease p=0.008). Kruppel-like factor 4 (KLF4) (p=0.007) targeted miR-145-5p were significantlyreduced and EMT markers were significantly changed in miR-145-5p transfected cells (E-Cad increase p=0.0005; Vimentin decrease p=0.006).Conclusion: miR-34a-5p and miR-145-5p may have an impact on the breast cancer cell line MDA-MB-231 proliferation and EMT mechanism. Atthe same time, according to our study results, it was revealed that E2F1, MEK1 and CDK4 genes, whose expression level decreased after transfectionof mimic miR-34a-5p, could be targeted by miR-34a-5p in breast cancer, and that the expression level of KLF4, which decreased as a result of mimicmiR-145-5p transfection, could be the target.