A summary for molecular regulations of miRNAs in breast cancer

• The current review highlights the molecular evidence of miRNA involvement in cancer progression, metastasis, and drug resistance.
• Based on this role of miRNA in breast cancer, we could suggest a combination of many miRNAs to be used in targeting different breast cancer pathways.
• This combination could also be used in conjunction with standard treatments to increase their efficiency. Such a protocol might have the advantage of preserving patients from chemotherapy-mediated injury.

BackgroundBreast cancer is the most frequently diagnosed cancer and the leading cause of cancer-related death among women worldwide. MicroRNAs (miRNAs) are naturally-occurring, non-coding small RNA molecules that can modulate protein coding-genes, which makes it contributing to nearly all the physiological and pathological processes. Progression of breast cancer and resistance to endocrine therapies have been attributed to the possibility of hormone-responsive miRNAs involved in the regulation of certain signaling pathways.MethodologyThis review introduces better understanding of miRNAs to provide promising advances for treatment. miRNAs have multiple targets, and they were found to regulate different signaling pathways; consequently it is important to characterize their mechanisms of action and their cellular targets in order to introduce miRNAs as novel and promising therapies.ResultsThis review summarizes the molecular mechanisms of miRNAs in TGF-beta signaling, apoptosis, metastasis, cell cycle, ER-signaling, and drug resistance.ConclusionFinally, miRNAs will be introduced as promising molecules to be used in the fight against breast cancer and its developed drug resistance.