The regulatory role of miRNAs on VDR in breast cancer.

Triple negative breast cancer (TNBC) has been associated with the lack of three hormone receptors; estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER-2). However, a host of other steroid hormone receptors such as vitamin D receptor (VDR) is present in TNBC, and the role of these hormone receptors in breast tumorigenesis is unclear. The levels of microRNAs (miRNAs) are also expressed differently than in normal mammary epithelial cells. miRNAs are regulatory RNAs involved in various cellular functions, mainly gene silencing. Here, we reviewed the literature surrounding miRNAs in breast cancer, and performed in silico analysis to determine whether there was a correlation between levels of VDR in relation to miRNAs important in breast cancer development and tumorigenesis. We identified three miRNAs of interest, specifically, miR-23, miR-124, and miR-125. Through this research we determined the possibility that these miRNAs play an important role in controlling VDR activity and by virtue the development of breast cancer.