Identification of microRNA-93 as a functional dysregulated miRNA in triple-negative breast cancer.

MicroRNAs (miRNAs) are widely recognized as key players in cancer progression and drug resistance, but less is known about the role of miRNAs in triple-negative (estrogen receptor, progesterone receptor, and HER-2/neu) breast cancer (TNBC). The aim of the present study was to examine the expression profile of miRNAs and to explore their possible roles in TNBC. Differentially expressed miRNAs were identified by miRNA microarray and verified by quantitative real-time polymerase chain reaction. The expression of miR-93 was assessed by in situ hybridization in 119 cases of breast cancer. Cell proliferation potential was examined by MTT assay. Cell migration and invasion abilities were evaluated by a wound healing assay and transwell invasion or migration assay. Seven upregulated and ten downregulated miRNAs in TNBC were identified. The miR-93 expression level in TNBC tissues was significantly higher than that in non-triple-negative breast cancer tissues. The potentials of proliferation, invasion, and metastasis in breast cancer MCF-7 cells were promoted by ectopic transfection of miR-93. Our study found several distinct differentially expressed miRNAs in TNBC, as compared to non-triple-negative breast cancer. Among them, miR-93 may be considered as a biomarker associated with the biological and clinical characteristics of human TNBC.