miR-141 and miR-375 induction and release are different from PSA mRNA and PCA3 upon androgen stimulation of LNCaP cells

Recent studies have demonstrated the differential expression of miR-141 and miR-375 in circulation of patients with advanced/metastatic prostate cancer (PCa). The aim of this study was to investigate the regulation of miR-141 and miR-375 by androgens and their release into the incubation medium in relation to prostate-specific antigen (PSA) mRNA and prostate cancer antigen 3 (PCA3). Plasma levels of these molecules were measured in a small cohort of patients with localized PCa. As an in vitro cell model we used androgen-sensitive LNCaP cells exposed to an androgen ablation of 48 h, and then treated with dihydrotestosterone (DHT) for 24 h. Expression of the four RNA molecules was measured by quantitative polymerase chain reaction (qPCR). miR-141 and miR-375 were induced in a dose-dependent manner where the median stimulation reached only 1.5-fold at maximum. The effect of DHT on PSA mRNA (up to 30-fold) and PCA3 (up to 195-fold) was much more evident. With regard to the release into the incubation medium, similar results were obtained with the exception of PCA3. At the highest DHT dose (100 nM), median miR-141 and miR-375 release was increased 1.7- and 1.4-fold (P= 0.07), respectively. DHT treatment led to a significant release of PSA mRNA (up to 12-fold) into the medium while PCA3 could not be amplified from the incubation medium. In plasma only PCA3 differed significantly between localized PCa patients and healthy subjects. In conclusion, our study provides evidence that miR-141 and miR-375 are increasingly released into incubation medium from androgen-stimulated cells. However, the extent of their induction was weaker than PSA mRNA or PCA3, suggesting differential regulation by androgens.