title: Systematic analysis of microRNAs targeting the androgen receptor in prostate cancer cells.
abstract: Androgen receptor (AR) is expressed in all stages of prostate cancer progression, including in castration-resistant tumors. Eliminating AR function continues to represent a focus of therapeutic investigation, but AR regulatory mechanisms remain poorly understood. To systematically characterize mechanisms involving microRNAs (miRNAs), we conducted a gain-of function screen of 1129 miRNA molecules in a panel of human prostate cancer cell lines and quantified changes in AR protein content using protein lysate microarrays. In this way, we defined 71 unique miRNAs that influenced the level of AR in human prostate cancer cells. RNA sequencing data revealed that the 3'UTR of AR (and other genes) is much longer than currently used in miRNA target prediction programs. Our own analyses predicted that most of the miRNA regulation of AR would target an extended 6 kb 3'UTR. 3'UTR-binding assays validated 13 miRNAs that are able to regulate this long AR 3'UTR (miR-135b, miR-185, miR-297, miR-299-3p, miR-34a, miR-34c, miR-371-3p, miR-421, miR-449a, miR-449b, miR-634, miR-654-5p, and miR-9). Fifteen AR downregulating miRNAs decreased androgen-induced proliferation of prostate cancer cells. In particular, analysis of clinical prostate cancers confirmed a negative correlation of miR-34a and miR-34c expression with AR levels. Our findings establish that miRNAs interacting with the long 3'UTR of the AR gene are important regulators of AR protein levels, with implications for developing new therapeutic strategies to inhibit AR function and androgen-dependent cell growth.
authors.affiliation: Medical Biotechnology, VTT Technical Research Centre of Finland, Turku, Finland. paivi.ostling@vtt.fi
authors.forename: Päivi
authors.initials: P
authors.lastname: Östling
authors.forename: Suvi-Katri
authors.initials: SK
authors.lastname: Leivonen
authors.forename: Anna
authors.initials: A
authors.lastname: Aakula
authors.forename: Pekka
authors.initials: P
authors.lastname: Kohonen
authors.forename: Rami
authors.initials: R
authors.lastname: Mäkelä
authors.forename: Zandra
authors.initials: Z
authors.lastname: Hagman
authors.forename: Anders
authors.initials: A
authors.lastname: Edsjö
authors.forename: Sara
authors.initials: S
authors.lastname: Kangaspeska
authors.forename: Henrik
authors.initials: H
authors.lastname: Edgren
authors.forename: Daniel
authors.initials: D
authors.lastname: Nicorici
authors.forename: Anders
authors.initials: A
authors.lastname: Bjartell
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Ceder
authors.forename: Merja
authors.initials: M
authors.lastname: Perälä
authors.forename: Olli
authors.initials: O
authors.lastname: Kallioniemi
mesh_terms: D020413:3' Untranslated Regions; D015153:Blotting, Western; D045744:Cell Line, Tumor; D015870:Gene Expression; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D035683:MicroRNAs / Q000235:genetics*; D011471:Prostatic Neoplasms / Q000235:genetics*; D040081:Protein Array Analysis; D011944:Receptors, Androgen / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D020413:3' Untranslated Regions; D035683:MicroRNAs; D011944:Receptors, Androgen