The Androgen Receptor Can Promote β-Catenin Nuclear Translocation Independently of Adenomatous Polyposis Coli

Abstract

We provide evidence that the androgen receptor (AR) can promote nuclear translocation of beta-catenin in LNCaP and PC3 prostate cancer cells. Using AR-expressing cells (LNCaP) and non-AR-expressing cells (PC3) we showed by time course cell fractionation that the AR can shuttle beta-catenin into the nucleus when exposed to exogenous androgen. Cells exposed to the synthetic androgen, R1881, show distinct, punctate, nuclear co-localization of the AR and beta-catenin. We further showed that the AR does not interact with adenomatous polyposis coli or glycogen synthase kinase-3beta and, therefore, conclude that androgen-mediated transport of beta-catenin occurs through a distinct pathway. The minimal necessary components of the AR and beta-catenin required for binding nuclear accumulation of beta-catenin nuclear import appears to be the DNA/ligand binding regions and the Armadillo repeats of beta-catenin. We also employed a novel DNA binding assay to illustrate that beta-catenin has the capacity to bind to the probasin promoter in an AR-dependent manner. The physiological relevance of AR-mediated transport of beta-catenin and binding to an AR promoter appeared to be a substantial increase in AR transcriptional reporter activity. AR-mediated import represents a novel mode of nuclear accumulation of beta-catenin.