Compound A inhibits bladder cancer growth predominantly via glucocorticoid receptor transrepression.

Recent evidence indicates that glucocorticoids (GCs) suppress bladder cancer cell invasion throughthe GC receptor (GR) pathway, whereas androgen-mediated androgen receptor (AR) signals inducebladder tumor progression. In this study, we assessed the effects of 2-(4-acetoxyphenyl)-2-chloro-N-methyl-ethylammonium chloride (compound A [CpdA]), which was shown to function asnot only a GR modulator but also an AR antagonist, on the growth of bladder cancer. In GR/ARpositivecells, CpdA strongly inhibited cell proliferation and colony formation as well as increasedG1 phase-arrested cell population and apoptosis. Specifically, CpdA at 1?Mdecreased cell viabilityof TCCSUP/UMUC3-control-short hairpin RNA (shRNA), TCCSUP/UMUC3-GR-shRNA, and TCCSUP/UMUC3-AR-shRNA by 50%/67%, 25%/26%, and 38%/58%, respectively. CpdA also inhibited cellmigration and invasion of GR/AR-positive (up to 61% decrease) and GR-positive/AR-silencing (upto 51% decrease) lines and, less strongly, those of GR-silencing/AR-positive lines (up to 35%decrease). Additionally, in UMUC3-control xenograft-bearing male mice, CpdA more stronglysuppressed tumor growth than dexamethasone or hydroxyflutamide. In reporter gene assays,CpdA failed to induce GR transactivation, whereas it antagonized dihydrotestosterone-enhancedAR transactivation. In contrast, CpdA reduced nuclear factor (NF)-?B and activator protein 1transcriptional activities, indicating induction of GR-mediated transrepression. Correspondingly,the expression of NF-?B-related molecules, matrix metalloproteinase-2, matrix metalloproteinase-9, interleukin-6, and vascular endothelial growth factor, was significantly down-regulatedby CpdA in control lines but not in GR-silencing cells. Moreover, coimmunoprecipitation showedthat CpdA promoted the interactions between GR and NF-?B. Thus, CpdA likely inhibits bladdercancer growth predominantly via inducing GR transrepression and at least partially mediatedthrough the AR pathway, suggesting its effects more beneficial than GCs/pure GR ligands or ARantagonists. (Molecular Endocrinology 29: 1486–1497, 2015)