MP49-11 THE RHOA EFFECTOR PROTEIN KINASE N1 AS A TARGET FOR SELECTIVE ANDROGEN DEPRIVATION THERAPY

Abstract

You have accessJournal of UrologyProstate Cancer: Basic Research IV1 Apr 2014MP49-11 THE RHOA EFFECTOR PROTEIN KINASE N1 AS A TARGET FOR SELECTIVE ANDROGEN DEPRIVATION THERAPY Adam DePriest, Kelly Duncan, Elena Pop, James Mohler, and Hannelore Heemers Adam DePriestAdam DePriest More articles by this author , Kelly DuncanKelly Duncan More articles by this author , Elena PopElena Pop More articles by this author , James MohlerJames Mohler More articles by this author , and Hannelore HeemersHannelore Heemers More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2014.02.1112AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail Introduction and Objectives The androgen receptor (AR) is the principal target for treatment of advanced prostate cancer (CaP). Androgen deprivation therapy (ADT) inhibits systemic AR action, but is not curative and causes severe side effects. The development of more effective and selective forms of ADT requires insights in the molecular mechanisms by which AR governs CaP progression. Our group has identified a novel mode of androgen action in which effects of androgens are mediated by Serum Response Factor (SRF). This mechanism controls a very small fraction of androgen action that is associated with aggressive CaP behavior. Androgen control over SRF action is achieved via androgen activation of the small GTPase RhoA. Here, the signal transduction that conveys androgen-responsiveness from RhoA to SRF, and its potential for selective inhibition of SRF-mediated androgen action, is identified. Methods An siRNA screen was performed to identify the RhoA effector protein(s) that mediates signaling from androgen-activated RhoA to SRF. qRT-PCR, custom oligoarray, promoter-reporter transfection and Western blotting approaches were used to study androgen-responsiveness of Androgen Response Element (ARE)-driven AR target genes or CArG box-driven SRF target genes. Androgen-stimulated (AS) and castration-recurrent (CR) CaP cells were treated with siRNAs targeting the RhoA effector Protein Kinase N1 (PKN1) or the PKN1 inhibitor lestaurtinib. Validation studies involved CaP cell lines that (over)express wild-type RhoA, dominant-active RhoA, dominant-negative RhoA, wild-type PKN1, or PKN1 forms mutated in its kinase domain or RhoA-interacting regions. Results The RhoA effector PKN1 was isolated as key mediator of androgen-responsive SRF action. PKN1 is overexpressed in CaP, where its overexpression has been correlated with CaP dedifferentiation. Loss of PKN1 decreased the androgen-responsiveness of SRF target genes, but affected androgen regulation of only 12 of 452 (or 2.6%) of ARE-driven genes. PKN1-dependent androgen regulation of SRF target genes was maintained in AS and CR CaP cells and in CaP cells that overexpress wild-type or dominant-active RhoA. Mutation of PKN1’s kinase domain or RhoA interaction sites attenuated androgen regulation of SRF target genes. PKN1 inhibitor lestaurtinib preferentially impeded androgen regulation of SRF target genes over that of ARE-driven genes. Conclusions PKN1 inhibitors may represent more selective forms of ADT that affect only androgen-dependent events that underlie CaP progression. © 2014FiguresReferencesRelatedDetails Volume 191Issue 4SApril 2014Page: e506 Peer Review Report Advertisement Copyright & Permissions© 2014MetricsAuthor Information Adam DePriest More articles by this author Kelly Duncan More articles by this author Elena Pop More articles by this author James Mohler More articles by this author Hannelore Heemers More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...