Roles of circulating microRNA(s) in human breast cancer

miRNAs are short non-coding RNA molecules that regulate the expression of mRNA post-transcriptionally. MiRNAs that are secreted into the circulation, also termed circulating miRNAs, have been studied extensively for their roles in diagnosis, treatment and prognosis of human breast cancer. Breast cancer is the most prevalent female cancer and is associated with key cancer hallmarks including sustained proliferation, evasion of apoptosis, increased invasion, enhanced metastases, initation of inflammation, induction of angiogenesis, metabolic derangement and immune dysregulation. This review aimed to explore the relationships between circulating miRNAs and different breast cancer hallmarks. Besides, the advantages, challenges and clinical application of using circulating miRNAs in human breast cancer management were also discussed.