Comuzzi Barbara, Lambrinidis Leonidas, Rogatsch Hermann, Godoy-Tundidor Sonia, Knezevic Nikola, Krhen Ivan, Marekovic Zvonimir, Bartsch Georg, Klocker Helmut, Hobisch Alfred, Culig Zoran
Department of Urology, University of Innsbruck, Innsbruck, Austria.
Am J Pathol. 2003 Jan;162(1):233-41. doi: 10.1016/S0002-9440(10)63814-X.
Progression of human prostate cancer toward therapy resistance occurs in the presence of wild-type or mutated androgen receptors (ARs) that, in some cases, exhibit aberrant activation by various steroid hormones and anti-androgens. The AR associates with a number of co-activators that possess histone acetylase activity and act as bridging molecules to components of the transcription initiation complex. In previous reports, it was shown that the transcriptional co-activator CREB (cAMP response element-binding protein)-binding protein (CBP) enhances AR activity in a ligand-dependent manner. In the present study, we have investigated whether CBP modifies antagonist/agonist balance of the nonsteroidal anti-androgens hydroxyflutamide and bicalutamide. In prostate cancer DU-145 cells, which were transiently transfected with CBP cDNA, hydroxyflutamide enhanced AR activity to a greater extent than bicalutamide in the presence of either wild-type or the mutated AR 730 val-->met. In two sublines of LNCaP cells that contain the mutated AR 877 thr-->ala and overexpressed CBP, increase in AR activity was observed after treatment with hydroxyflutamide but not with bicalutamide. Anti-androgens did not influence AR expression in cells transfected with CBP cDNA, as judged by Western blot analysis. Endogenous CBP protein was detected by Western blot in nuclear extracts from the three prostate cancer cell lines, LNCaP, PC-3, and DU-145, all derived from therapy-resistant prostate cancer. In addition, CBP was expressed in both basal and secretory cells of benign prostate epithelium, high-grade prostate intraepithelial neoplasia, and prostate cancer clinical specimens, as evidenced by immunohistochemical staining. Taken together, our findings demonstrate the selective enhancement of agonistic action of the anti-androgen hydroxyflutamide by the transcriptional co-activator CBP, which is a new, potentially relevant mechanism contributing to the acquisition of therapy resistance in prostate cancer.
人类前列腺癌向治疗抗性的进展发生在野生型或突变型雄激素受体（ARs）存在的情况下，在某些情况下，这些受体可被各种类固醇激素和抗雄激素异常激活。AR与许多具有组蛋白乙酰化酶活性的共激活因子相关联，并作为转录起始复合物成分的桥梁分子。在先前的报道中，已表明转录共激活因子CREB（cAMP反应元件结合蛋白）结合蛋白（CBP）以配体依赖性方式增强AR活性。在本研究中，我们研究了CBP是否会改变非甾体抗雄激素羟基氟他胺和比卡鲁胺的拮抗剂/激动剂平衡。在瞬时转染了CBP cDNA的前列腺癌DU-145细胞中，在存在野生型或突变型AR 730 val→met的情况下，羟基氟他胺比卡鲁胺更能增强AR活性。在含有突变型AR 877 thr→ala并过表达CBP的LNCaP细胞的两个亚系中，用羟基氟他胺处理后观察到AR活性增加，但用比卡鲁胺处理后未观察到。通过蛋白质印迹分析判断，抗雄激素不影响转染了CBP cDNA的细胞中的AR表达。通过蛋白质印迹在来自三种前列腺癌细胞系LNCaP、PC-3和DU-145的核提取物中检测到内源性CBP蛋白，这三种细胞系均来源于抗治疗性前列腺癌。此外，通过免疫组织化学染色证明，CBP在良性前列腺上皮、高级别前列腺上皮内瘤变和前列腺癌临床标本的基底细胞和分泌细胞中均有表达。综上所述，我们的研究结果表明转录共激活因子CBP选择性增强了抗雄激素羟基氟他胺的激动作用，这是一种导致前列腺癌获得治疗抗性的新的潜在相关机制。
