Beneficial and detrimental aspects of miRNAs as chief players in breast cancer: A comprehensive review

Breast cancer (BC) is the most common cancer in women and poses a serious threat to their health. Despite familiarity with factors affecting its etiology, initiation, progression, treatment strategies, and even resistance to therapy, it is considered a significant problem for women. However, several factors have greatly affected previous aspects affecting BC progression and treatment in the last decades. miRNAs are short non-coding RNA sequences that regulate gene expression by inhibiting the translation of the target mRNA. miRNAs play a crucial role in BC pathogenesis by promoting cancer stem cell (CSCs) proliferation, postponing apoptosis, continuing the cell cycle, and endorsing invasion, angiogenesis, and metastasis. Similarly, miRNAs influence important BC-related molecular pathways such as the PI3K/AKT/mTOR signaling pathway, the Wnt/β-catenin system, JAK/STAT signaling pathway, and the MAPK signaling pathway. Moreover, miRNAs affect the treatment response of BC to chemo and radiotherapy. Consequently, this review aims to provide an acquainted summary of oncomiRs and tumor suppressor (TS) miRNAs and their potential role in BC pathogenesis and therapy responses by focusing on the molecular pathways that drive them.