Mediwala SN, Sun H, Szafran AT, Hartig SM, Sonpavde G, Hayes TG, Thiagarajan P, Mancini MA, Marcelli M. The activity of the androgen receptor variant AR-V7 is regulated by FOXO1 in a PTEN-PI3K-AKT-dependent way.
Prostate 2013;
73:267-77. [PMID:
22821817 PMCID:
PMC3961010 DOI:
10.1002/pros.22566]
[Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2012] [Accepted: 06/27/2012] [Indexed: 11/07/2022]
Abstract
BACKGROUND
The androgen receptor (AR) AR-V7 splice isoform is a constitutively active outlaw transcription factor. Transition of prostate cancer (PC) to the castration-resistant phenotype correlates with AR-V7 accumulation, suggesting that PC progression in patients refractory to conventional therapy is due to the activity of this AR isoform. The mechanism of AR-V7 constitutive activation is not known.
METHODS
We analyzed potential signaling pathways associated with AR-V7 constitutive activation in PTEN (-) PC-3 and LNCaP cells. We used transient and stable transfection, reporter gene assay, RNAi technology together with a number of kinase inhibitors to determine if AR-V7 activation is linked to a kinase-dependent signaling pathway.
RESULTS
In these cell lines, AR-V7 transcriptional activity was inhibited by LY294002, Wortmanin, and AKT inhibitor II. Analysis of the contributing mechanisms demonstrated the involvement of the Phosphatidylinositol 3-kinase (PI3K)-AKT-FOXO1 signaling pathway, and a significant reduction of AR-V7 constitutive activity under conditions of PTEN reactivation.
CONCLUSIONS
Our study identifies a pathway regulating AR-V7 constitutive activity and potential therapeutic targets for the treatment of castration-resistant PC.
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