Department of Urology and Cancer Center, University of California at Davis, Sacramento, California; Graduate Program of Pharmacology and Toxicology, University of California at Davis, Sacramento, California.
Prostate. 2013 Nov;73(15):1614-22. doi: 10.1002/pros.22615. Epub 2013 Aug 6.
Treatment of primary prostate cancer (CaP) is the withdrawal of androgens. However, CaP eventually progresses to grow in a castration-resistant state due to aberrant activation of androgen receptor (AR). Understanding the mechanisms leading to the aberrant activation of AR is critical to develop effective therapy. We have previously identified Rho GDP Dissociation Inhibitor alpha (GDIα) as a novel suppressor in prostate cancer. In this study, we examine the effect of GDIα on AR signaling in prostate cancer cells.
GDIα was transiently or stably transfected into several prostate cancer cell lines including LNCaP, C4-2, CWR22Rv1, and DU145. The regulation of AR expression by GDIα was analyzed by qRT-PCR and Western blot. AR activity was measured by luciferase reporter assays and electrophoretic mobility shift analysis (EMSA). Immunofluorescence assay was performed to study AR nuclear translocation. The interaction between GDIα and AR was examined by co-immunoprecipitation assays.
In this study, we have identified GDIα as a negative regulator of AR signaling pathway. Overexpression of GDIα downregulates AR expression at both mRNA and protein levels. Overexpression of GDIα is able to prevent AR nuclear translocation and inhibit transactivation of AR target genes. Co-immunoprecipitation assays showed that GDIα physically interacts with the N-terminal domain of AR.
GDIα suppresses AR signaling through inhibition of AR expression, nuclear translocation, and recruitment to androgen-responsive genes. GDIα regulatory pathway may play a critical role in regulating AR signaling and prostate cancer growth and progression.
治疗原发性前列腺癌（CaP）的方法是去除雄激素。然而，由于雄激素受体（AR）的异常激活，CaP 最终会发展为去势抵抗状态。了解导致 AR 异常激活的机制对于开发有效的治疗方法至关重要。我们之前已经确定 Rho GDP 解离抑制剂 alpha（GDIα）是前列腺癌的一种新型抑制物。在这项研究中，我们研究了 GDIα 对前列腺癌细胞中 AR 信号的影响。
将 GDIα 瞬时或稳定转染到包括 LNCaP、C4-2、CWR22Rv1 和 DU145 在内的几种前列腺癌细胞系中。通过 qRT-PCR 和 Western blot 分析 GDIα 对 AR 表达的调节。通过荧光素酶报告基因检测和电泳迁移率变动分析（EMSA）测量 AR 活性。通过免疫荧光测定研究 AR 核易位。通过共免疫沉淀测定检查 GDIα 和 AR 之间的相互作用。
在这项研究中，我们确定 GDIα 是 AR 信号通路的负调节剂。GDIα 的过表达在 mRNA 和蛋白水平下调 AR 表达。GDIα 的过表达能够阻止 AR 核易位并抑制 AR 靶基因的转录激活。共免疫沉淀测定表明，GDIα 与 AR 的 N 端结构域物理相互作用。
GDIα 通过抑制 AR 表达、核易位和募集到雄激素反应基因来抑制 AR 信号。GDIα 调节途径可能在调节 AR 信号和前列腺癌的生长和进展中发挥关键作用。
