Liu S, Vinall R L, Tepper C, Shi X-B, Xue L R, Ma A-H, Wang L-Y, Fitzgerald L D, Wu Z, Gandour-Edwards R, deVere White R W, Kung H-J
Department of Biochemistry and Molecular Medicine, School of Medicine and Cancer Center, University of California, Sacramento, CA, USA.
Oncogene. 2008 Jan 17;27(4):499-505. doi: 10.1038/sj.onc.1210671. Epub 2007 Jul 23.
We have previously demonstrated that human H2-relaxin can mediate androgen-independent growth of LNCaP through a mechanism that involves the activation of the androgen receptor (AR) signaling pathway. The goal of the current study is to elucidate the mechanism(s) by which H2-relaxin causes activation of the AR pathway. Our data indicate that there is cross-talk between AR and components of the Wnt signaling pathway. Addition of H2-relaxin to LNCaP cells resulted in increased phosphorylation of protein kinase B (Akt) and inhibitory phosphorylation of glycogen synthase kinase-3beta (GSK-3beta) with subsequent cytoplasmic accumulation of beta-catenin. Immunoprecipitation and immunocytochemical studies demonstrated that the stabilized beta-catenin formed a complex with AR, which was then translocated into the nucleus. Chromatin immunoprecipitation analysis determined that the AR/beta-catenin complex binds to the proximal region of the prostate-specific antigen promoter. Inhibition of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway, using LY294002, prevented both H2-relaxin-mediated phosphorylation of Akt and GSK-3beta and translocation of beta-catenin/AR into the nucleus. Knockdown of beta-catenin levels using a beta-catenin-specific small interfering RNA inhibited H2-relaxin-induced AR activity. The combined data demonstrate that PI3K/Akt and components of the Wnt pathway can facilitate H2-relaxin-mediated activation of the AR pathway.
我们之前已经证明，人H2-松弛素可通过涉及雄激素受体（AR）信号通路激活的机制介导LNCaP细胞的雄激素非依赖性生长。本研究的目的是阐明H2-松弛素激活AR通路的机制。我们的数据表明，AR与Wnt信号通路的组分之间存在相互作用。向LNCaP细胞中添加H2-松弛素导致蛋白激酶B（Akt）磷酸化增加以及糖原合酶激酶-3β（GSK-3β）的抑制性磷酸化，随后β-连环蛋白在细胞质中积累。免疫沉淀和免疫细胞化学研究表明，稳定的β-连环蛋白与AR形成复合物，然后转运至细胞核。染色质免疫沉淀分析确定，AR/β-连环蛋白复合物结合至前列腺特异性抗原启动子的近端区域。使用LY294002抑制磷脂酰肌醇3-激酶（PI3K）/Akt通路，可阻止H2-松弛素介导的Akt和GSK-3β磷酸化以及β-连环蛋白/AR转运至细胞核。使用β-连环蛋白特异性小干扰RNA敲低β-连环蛋白水平可抑制H2-松弛素诱导的AR活性。综合数据表明，PI3K/Akt和Wnt通路的组分可促进H2-松弛素介导的AR通路激活。
