An update review of deregulated tumor suppressive microRNAs and their contribution in various molecular subtypes of breast cancer

Background: Breast cancer (BC) is histologically classified into hormone-receptor + (ER + , PR + ), human epidermal growth factor receptor-2 + (Her2 + ), and triple-negative breast cancer (TNBC) types. The important contribution of tumor-suppressive (TS) microRNAs (miRs) in BC development and treatment have been well-acknowledged in the literature. Objective: The present review focused on the contribution of recently examined TS miRs in the progression and treatment of various histological subtypes of BC. Results: In summary, various miRs have tumor-suppressive roles in BC, so that their aberrant expression leads to the abnormality in the cellular processes such as enhanced cell growth, decreased apoptosis, cell migration and metastasis, and decreased sensitivity to chemotherapy through deregulated expression of oncogene targets of TS miRs. Conclusion: TS miRs could be regarded as a proper molecular target for target therapy of BC. However, further in vitro and in vivo investigations are required to confirm the exact molecular functions of TS miRs in BC cells to offer more efficient targeted therapies.