Identification of microRNAs dysregulated in TNBC 3. Functional evidence of microRNAs in TNBC 4. MicroRNAs as prognostic markers in TNBC

Triple-negative breast cancer (TNBC) is defined by the absence of expression of the estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2). TNBC exhibits a more aggressive phenotype and a poorer clinical outcome compared to other breast cancer subgroups, accounting for 15-20% of total breast cancer cases. To date, the treatment strategies for TNBC are limited to surgery, chemotherapy and radiation, owing to the lack of effective therapeutic targets. Therefore, it is important to identify specific targets for TNBCs. MicroRNAs (miRNAs), a family of small non-coding RNAs regulating gene expression, are an emerging class of regulators of various biological processes, including cell proliferation, invasion, epithelialmesenchymal transition (EMT) and drug resistance. Actually, miRNAs may serve as a novel therapeutic target in TNBC, and here we review current correlated researches and provide our own profiling results for the miRNAs expressed in TNBC cell lines. The present study offers an additional insight into the potential miRNAs involved in the regulation of TNBC.