Abstract
MicroRNAs (miRNAs) are small non-coding RNA molecules which function as critical post-transcriptional gene regulators of various biological functions. Generally, miRNAs negatively regulate gene expression by binding to their selective messenger RNAs (mRNAs), thereby leading to either mRNA degradation or translational repression, depending on the degree of complementarity with target mRNA sequences. Aberrant expression of these miRNAs has been linked etiologically with various human diseases including breast cancer. Different cellular pathways of breast cancer development such as cell proliferation, apoptotic response, metastasis, cancer recurrence and chemoresistance are regulated by either the oncogenic miRNA (oncomiR) or tumor suppressor miRNA (tsmiR). In this review, we highlight the current state of research into miRNA involved in breast cancer, with particular attention to articles published between the years 2000 to 2019, using detailed searches of the databases PubMed, Google Scholar, and Scopus. The post-transcriptional gene regulatory roles of various dysregulated miRNAs in breast cancer and their potential as therapeutic targets are also discussed.
Highlights
MicroRNAs are a family of evolutionarily conserved small, endogenous, single-stranded and non-protein coding RNAs spanning 19 to 25 nucleotides in length [1]
This review considers the role of miRNAs associated with breast cancer, explores their contributions to the etiology of the disease and discusses the prospects of miRNA-based breast cancer therapeutic strategies
Huang et al revealed that the overexpression of miR-26a-5p with miRNA mimic transfection induced proliferative growth of breast cancer cells, with a marked decreased in the expression levels of cell cycle regulators cyclin D1, CDK4, and CDK6, and increased the expression of p21, p27, and p53 tumor suppressor protein [67]
Summary
MicroRNAs are a family of evolutionarily conserved small, endogenous, single-stranded and non-protein coding RNAs spanning 19 to 25 nucleotides in length [1]. Pri-miRNAs are processed by a microprocessor complex, Drosha–DiGeorge syndrome critical region gene 8 (DGCR8), into the precursor transcripts (pre-miRNAs), which are approximately 70 nucleotides long and in hairpin form [14,15]. Breast cancer is a complex neoplastic disease, comprising the processes of tumor initiation and growth [38], metastasis and invasion [39], and angiogenesis [40], with an additional significant possibility of relapse [41]. These malignant changes occur when the cellular and molecular signaling pathways of the mammary cells are disturbed or dysregulated [42]. This review considers the role of miRNAs associated with breast cancer, explores their contributions to the etiology of the disease and discusses the prospects of miRNA-based breast cancer therapeutic strategies
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