MicroRNAs in the development and neoplasia of the mammary gland [version 1; referees: 1 approved, 2 approved with reservations]

• Main Author: Manoj Kumar Jena
• Format: Article
• Language: English
• Published: F1000 Research Ltd 2017-06-01
• Series: F1000Research
• Subjects: Breast Diseases: Benign & Malignant; Control of Gene Expression
• Online Access: https://f1000research.com/articles/6-1018/v1

Study on the role of microRNAs (miRs) as regulators of gene expression through posttranscriptional gene silencing is currently gaining much interest,due to their wide involvement in different physiological processes. Understanding mammary gland development, lactation, and neoplasia in relation to miRs is essential. miR expression profiling of the mammary gland from different species in various developmental stages shows their role as critical regulators of development. miRs such as miR-126, miR-150, and miR-145 have been shown to be involved in lipid metabolism during lactation. In addition, lactogenic hormones influence miR expression as evidenced by overexpression of miR-148a in cow mammary epithelial cells, leading to enhanced lactation. Similarly, the miR-29 family modulates lactation-related gene expression by regulating DNA methylation of their promoters. Besides their role in development, lactation and involution, miRs are responsible for breast cancer development. Perturbed estrogen (E2) signaling is one of the major causes of breast cancer. Increased E2 levels cause altered expression of ERα, and ERα-miR cross-talk promotes tumour progression. miRs, such as miR-206, miR-34a, miR-17-5p, and miR-125 a/b are found to be tumour suppressors; whereas miR-21, miR-10B, and miR-155 are oncogenes.Studies using an ACI rat model showed similar findings of miR dysregulation due to excess E2, and a natural phenol antioxidant ellagic acid showed therapeutic properties by reversing the miR dysregulation. This review focuses on the recent findings concerning the role of miRs in developmental stages of the mammary gland (mainly lactation and involution stages) and their involvement in breast cancer progression. Further studies in this area will help us understand the molecular details of mammary gland biology,as well as miRs that could be therapeutic targets of breast cancer.