Department of Internal Medicine, The University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA.
Int J Oncol. 2010 Feb;36(2):459-67.
Heat shock protein (hsp) 70-1 (hsp70-1) is overexpressed in human prostate cancer cells and may play important roles in prostate cancer resistance to conventional therapies. The purpose of this study was to investigate whether androgen receptor (AR) and its signaling regulate hsp70-1 expression. Several lines of AR-positive (LNCaP, LAPC-4, and 22Rv1) and -negative (PC-3, DU145, WPE1-NB14 and WPE1-NB-26) human prostatic cells were used in the study. Dihydrotestosterone (DHT) enhanced hsp70-1 expression in LNCaP cells. Expression of hsp70-1 in LNCaP cells was downregulated by the anti-androgens bicalutamide (Bic), and flutamide (Flut), and a newly identified AR signaling antagonist DL3. The downregulation of hsp70-1 by DL3 was also observed in LAPC-4 and 22Rv1 cells, but not in the four lines of AR-negative cells examined. Expression of hsp70-1 was also reduced by DL3 in PC-3 cells engineered with AR. On the other hand, knocking down AR in LNCaP cells by siRNA moderately reduced hsp70-1 level and abolished effects of DL3 on hsp70-1 expression. DL3 reduced hsp70-1 mRNA synthesis in cells and its in vitro gene transcription but did not significantly alter the stabilities of hsp70-1 mRNA and protein. Chromatin-immunoprecipitation (ChIP) assay showed that AR bound to the promoter region of HSPA1B gene, which was reduced in cells treated with DL3 or Bic. These data suggest that AR and its signaling regulate hsp70-1 expression in prostate cancer cells and that HSPA1B could be an AR target gene.
热休克蛋白 70-1（hsp70-1）在人前列腺癌细胞中过度表达，可能在前列腺癌对常规治疗的耐药性中发挥重要作用。本研究旨在探讨雄激素受体（AR）及其信号是否调节 hsp70-1 的表达。研究中使用了几株 AR 阳性（LNCaP、LAPC-4 和 22Rv1）和阴性（PC-3、DU145、WPE1-NB14 和 WPE1-NB-26）的人前列腺细胞。二氢睾酮（DHT）增强了 LNCaP 细胞中 hsp70-1 的表达。抗雄激素比卡鲁胺（Bic）和氟他胺（Flut）以及新鉴定的 AR 信号通路拮抗剂 DL3 下调了 LNCaP 细胞中 hsp70-1 的表达。在 LAPC-4 和 22Rv1 细胞中也观察到了 DL3 下调 hsp70-1 的作用，但在 4 株 AR 阴性细胞中未观察到。在 AR 转染的 PC-3 细胞中，DL3 也降低了 hsp70-1 的表达。另一方面，siRNA 下调 LNCaP 细胞中的 AR 水平适度降低了 hsp70-1 水平，并消除了 DL3 对 hsp70-1 表达的影响。DL3 降低了细胞中 hsp70-1 mRNA 的合成及其体外基因转录，但对 hsp70-1 mRNA 和蛋白的稳定性没有显著影响。染色质免疫沉淀（ChIP）试验表明，AR 结合于 HSPA1B 基因的启动子区域，而在用 DL3 或 Bic 处理的细胞中该区域减少。这些数据表明，AR 及其信号通路调节前列腺癌细胞中 hsp70-1 的表达，并且 HSPA1B 可能是 AR 的靶基因。
