Laboratory of Molecular Endocrinology, Department of Physiopathology, University of Concepcion, Concepcion, Chile.
Biochem Biophys Res Commun. 2011 Aug 19;412(1):13-9. doi: 10.1016/j.bbrc.2011.06.181. Epub 2011 Jul 5.
The disruption of stromal cell signals in prostate tissue microenvironment influences the development of prostate cancer to androgen independence. 1α,25-Dihydroxyvitamin D(3) (1,25D(3)) and glucocorticoids, either alone or in combination, have been investigated as alternatives for the treatment of advanced prostate cancers that fails androgen therapies. The effects of glucocorticoids are mediated by the intracellular glucocorticoid receptor (GR). Similarly, the effect of 1,25D(3) is mediated by the 1,25D(3) nuclear receptor (VDR). In this study, fibroblasts from benign- (BAS) and carcinoma-associated stroma (CAS) were isolated from human prostates to characterize VDR and GR function as transcription factors in prostate stroma. The VDR-mediated transcriptional activity assessed using the CYP24-luciferase reporter was limited to 3-fold induction by 1,25D(3) in 9 out of 13 CAS (70%), as compared to >10-fold induction in the BAS clinical sample pair. Expression of His-tagged VDR (Ad-his-VDR) failed to recover the low transcriptional activity of the luciferase reporter in 7 out of 9 CAS. Interestingly, expression of Ad-his-VDR successfully recovered receptor-mediated induction in 2 out of the 9 CAS analyzed, suggesting that changes in the receptor protein itself was responsible for decreased response and resistance to 1,25D(3) action. Conversely, VDR-mediated transcriptional activity was more efficient in 4 out of 13 CAS (30%), as compared to the BAS sample pair. Consistent with the reduced response to 1,25D(3) observed in CAS, chromatin immunoprecipitation (ChIP) assays indicated decreased recruitment of coactivators SRC-1/CBP, without major changes in the recruitment of VDR to the CYP24 promoter. In addition, we observed that GR-mediated transcriptional activity was also altered in CAS, as compared to BAS. Disruption of coactivators SRC-1/CBP recruitment may promote hormone resistance in CaP, and highlights the relevance of molecular diagnosis and drug design in tumor cell microenvironment.
前列腺组织微环境中基质细胞信号的破坏会影响前列腺癌向雄激素非依赖性的发展。1α,25-二羟维生素 D(3)(1,25D(3))和糖皮质激素，单独或联合使用，已被研究作为治疗雄激素治疗失败的晚期前列腺癌的替代方法。糖皮质激素的作用是通过细胞内糖皮质激素受体(GR)介导的。同样，1,25D(3)的作用是通过 1,25D(3)核受体(VDR)介导的。在这项研究中，从人前列腺中分离出良性(BAS)和癌相关基质(CAS)的成纤维细胞，以研究 VDR 和 GR 作为前列腺基质中的转录因子的功能。使用 CYP24-荧光素酶报告基因评估的 VDR 介导的转录活性在 13 个 CAS 中有 9 个(70%)被 1,25D(3)诱导 3 倍，而在 BAS 临床样本对中诱导超过 10 倍。在 9 个 CAS 中有 7 个，表达 His 标记的 VDR(Ad-his-VDR)未能恢复荧光素酶报告基因的低转录活性。有趣的是，在分析的 9 个 CAS 中有 2 个，表达 Ad-his-VDR 成功恢复了受体介导的诱导，这表明受体蛋白本身的变化是导致对 1,25D(3)作用的反应和抗性降低的原因。相反，在 13 个 CAS 中有 4 个(30%)VDR 介导的转录活性更有效，与 BAS 样本对相比。与在 CAS 中观察到的对 1,25D(3)的反应降低一致，染色质免疫沉淀(ChIP)分析表明，共激活因子 SRC-1/CBP 的募集减少，而 VDR 向 CYP24 启动子的募集没有重大变化。此外，我们观察到 GR 介导的转录活性在 CAS 中也发生了改变，与 BAS 相比。共激活因子 SRC-1/CBP 募集的破坏可能会促进 CaP 的激素抵抗，并强调了肿瘤细胞微环境中分子诊断和药物设计的相关性。
