The Influence of microRNAs in Regulation of Hormone Dependence in Prostate Cancer Cells

A spectrum of differentially expressed microRNAs was determined by the massively parallel sequencing method in normal healthy prostate tissues, in hormone-dependent prostate cancer samples, and in the LNCaP and DU145 cell lines. A set of microRNAs in tumors and prostate cancer (PCa) cell lines was identified on the basis of the changes in expression compared with that in normal prostate tissues. Twenty-seven aberrantly expressed microRNAs were detected in tumor tissues and ten of them showed significant changes in expression in LNCaP and DU145 cells. Seven of them demonstrated the change of the expression in the same direction in all the tumor samples as well as in the PCa cell lines. The expression of miR-148a changed in DU145 cells in the opposite direction compared with that in LNCaP cells and tumors. The expression of let-7c, let-7b, miR-99a, miR-125b-2, miR-100, miR-10a, and miR-31 was reversed in DU145 cells compared with LNCaP cells. However, these microRNAs exhibited no significant changes in expression in tumors. It turns out that the target of miR-148a, let-7b, and microRNAs, included in the miR-99a/let-7c/miR-125b-2 cluster, the expression of which increased in LNCaP cells and decreased in DU145 cells, is the insulin-like growth factor receptor gene 1 (IGF1R). The obtained data make it possible to assume that the differences in the effect of microRNAs in cell lines are connected with their repressive influence on IGF1R expression in hormone-sensitive LNCaP cells and an absence of such influence in the hormone-independent DU145 cell line.