Evaluation and Research Centre for Toxicology, Institute of Disease Control and Prevention, Academy of Military Medical Sciences, Beijing 100071, China.
Evaluation and Research Centre for Toxicology, Institute of Disease Control and Prevention, Academy of Military Medical Sciences, Beijing 100071, China; College of Life Science, Lanzhou University, Lanzhou, Gansu 730000, China.
Toxicol Lett. 2014 Sep 2;229(2):405-13. doi: 10.1016/j.toxlet.2014.07.003. Epub 2014 Jul 8.
Cadmium is a potential prostate carcinogen and can mimic the effects of androgen by a mechanism that involves the hormone-binding domain of the androgen receptor (AR), which is a key transcriptional factor in prostate carcinogenesis. We focused on transcriptional activity of AR to investigate the toxicity of cadmium exposure on human prostate cell lines. Cadmium increased the proliferative index of LNCaP and the proliferative effect was obstructed significantly by AR blocking agent. In luciferase assay, cadmium activated the transcriptional activity of AR in 293T cells co-transfected with wild-type AR and an ARE (AR response elements)-luciferase reporter gene. Cadmium also increased expression of PSA, a downstream gene of AR, whereas the metal had no significant effect on AR amount. AR is regulated by multiple posttranslational modifications including SUMOylation. SUMOylated AR shows a lower transcriptional activity. SUMO-specific protease 1 (SENP1) decreases AR SUMOylation by deconjugating AR-SUMO covalent bond. We detected that cadmium increased the amount of SENP1 in a dose and time dependent manner. Knocking down of SENP1 by RNAi led to decrease of PSA expression and transcriptional activity of AR in luciferase assay. Furthermore, co-immunoprecipitation (Co-IP) results showed that SUMOylation level of AR was decreased after cadmium treatment. In conclusion, our results indicated that cadmium-induced SENP1 enhanced AR transcriptional activity by decreasing AR SUMOylation.
镉是一种潜在的前列腺致癌物质，它可以通过一种机制模拟雄激素的作用，该机制涉及雄激素受体 (AR) 的激素结合域，AR 是前列腺癌发生的关键转录因子。我们专注于 AR 的转录活性，以研究镉暴露对人前列腺细胞系的毒性。镉增加了 LNCaP 的增殖指数，而 AR 阻断剂显著阻断了这种增殖作用。在荧光素酶测定中，镉在共转染野生型 AR 和 ARE（AR 反应元件）-荧光素酶报告基因的 293T 细胞中激活了 AR 的转录活性。镉还增加了 AR 下游基因 PSA 的表达，而金属对 AR 量没有显著影响。AR 通过多种翻译后修饰（包括 SUMOylation）进行调节。SUMOylated AR 显示出较低的转录活性。SUMO 特异性蛋白酶 1（SENP1）通过去共轭 AR-SUMO 共价键降低 AR SUMOylation。我们检测到镉以剂量和时间依赖的方式增加 SENP1 的数量。通过 RNAi 敲低 SENP1 导致 PSA 表达和荧光素酶测定中 AR 的转录活性降低。此外，共免疫沉淀（Co-IP）结果表明，镉处理后 AR 的 SUMOylation 水平降低。总之，我们的结果表明，镉诱导的 SENP1 通过降低 AR SUMOylation 增强了 AR 的转录活性。
