Dihydrotestosterone regulates expression of CD44 via miR-328-3p in triple-negative breast cancer cells

Triple-negative breast cancer (TNBC) is an aggressive subtype that lacks effective targeted therapeutics strategy and has poor prognosis. Targeting androgen receptor (AR) in TNBC is thought to be a promising approach. We hypothesized that AR, functioning as a transcription factor, controls cell behavior via regulating the expression of microRNA molecules (miRNAs). The expression of 84 breast cancer-specific miRNAs in MDA-MB-231 cells, a highly invasive TNBC model system, was investigated using PCR arrays following treatment of cells with 5α-dihydrotestosterone (DHT). The expression of 33 miRNAs was changed by more than 2 folds including miR-328-3p, which was up-regulated by 13 folds. Transfection of cells with either miR-328-3p mimic or anti-sense molecules decreased cell motility. DHT-mediated effect on the expression and function of CD44, a target of miR-328-3p, was investigated. CD44 expression and cell adhesion to hyaluronic acid (HA) were down-regulated when cells were treated with DHT or transfection with a miR-328-3p mimic. On the other hand, the AR antagonist, bicalutamide, or transfection of cells with miR-328-3p anti-sense molecules had the opposite effect. Cells transfected with miR-328-3p anti-sense molecules reduced the negative effect of DHT on CD44 expression and cell adhesion to HA. In addition, DHT further reduced the expression of CD44 and cell adhesion to HA in cells transfected with miR-328-3p mimic. These results strongly suggest that miRNAs can mediate AR regulation of breast cancer cells and that AR controls the expression of CD44 via miRNA-dependent and independent mechanisms.