miRNA as regulators of prostate carcinogenesis and endocrine and chemoresistance.

More therapy options are available for advanced prostate cancer, including novel inhibitors of androgen synthesis, anti-androgens, chemotherapeutics and targeted therapies. Although patients´ survival has been improved, management of castration therapy-resistant prostate cancer remains a challenge. Regulation of cellular events in cancer by small non-coding miRNAs is therefore an area of special interest. Overexpression of selected miRNA may lead to androgen independence and prostate cancer progression. miRNA may be considered also a biomarker in patients with prostate cancer. In contrast, diminished expression of tumor-suppressive miRNA in prostate cancer leads to enhanced proliferation, reduced apoptosis, increased migration, invasion and epithelial-to-mesenchymal transition. miRNA may be directly involved in regulation of chemosensitivity in prostate cancer. Experimental overexpression of selected miRNA in chemoresistant prostate cancer leads to inhibition of cellular stemness and epithelial-to-mesenchymal transition. Reduction of tumorsuppressive miRNA may also lead to hyperactivity of signaling pathways such as that of the epidermal growth factor receptor and mitogen-activated protein kinase. Although a considerable progress on miRNA research in prostate cancer has been achieved, therapeutic effects could be improved on the basis of development of novel delivery methods.