College of Veterinary Medicine, Northeast Agricultural University, Number 59, Mucai Street, Harbin 150030, PR China; Heilongjiang Vocational College of Animal Husbandry and Veterinary Science, Number 168, Yingbin Road, Shuangcheng, 150100, PR China.
Environ Toxicol Pharmacol. 2009 May;27(3):345-9. doi: 10.1016/j.etap.2008.11.012. Epub 2008 Dec 9.
Cadmium is a persistent pollutant that poses a threat to most biological organisms including birds. Although toxicity of cadmium is mainly linked to cancer, the mechanism of its carcinogenic activity remains poorly understood. Since DNA methylation is linked to cancer, we have examined the effect of cadmium on DNA methylation and DNMTs mRNA expression in hen liver and kidney. Sixty 50-day-old hyline-white hens were randomly allocated into 3 equal groups; a control group fed a basal diet, a low-dose group fed the basal diet spiked with 140mg/kg CdCl(2), and a high-dose group fed the basal diet spiked with 210mg/kg CdCl(2). After 60 days, liver and kidney samples were analysed for cadmium by FAAS, DNA methylation level by HPLC and DNMTs mRNA levels by semi-quantitative RT-PCR. The DNA methylation levels and the expressions of DNMT1 and DNMT3a mRNA in liver and kidney were significantly elevated by the cadmium treatment but there was no change in the expression of DNMT3b mRNA in the two tissues. The fact that cadmium increases DNA methylation and the expressions of DNMT1 and DNMT3a mRNA in liver and kidney suggests DNA methylation may be involved in the carcinogenic action of cadmium.
镉是一种持久性污染物，对包括鸟类在内的大多数生物有机体构成威胁。虽然镉的毒性主要与癌症有关，但它的致癌活性机制仍知之甚少。由于 DNA 甲基化与癌症有关，我们研究了镉对母鸡肝脏和肾脏中 DNA 甲基化和 DNMTs mRNA 表达的影响。将 60 只 50 日龄海兰白母鸡随机分为 3 组，对照组饲喂基础日粮，低剂量组饲喂基础日粮中添加 140mg/kg CdCl2，高剂量组饲喂基础日粮中添加 210mg/kg CdCl2。60 天后，用 FAAS 分析肝脏和肾脏中的镉含量，用 HPLC 分析 DNA 甲基化水平，用半定量 RT-PCR 分析 DNMTs mRNA 水平。镉处理后肝脏和肾脏中的 DNA 甲基化水平以及 DNMT1 和 DNMT3a mRNA 的表达显著升高，但两种组织中 DNMT3b mRNA 的表达没有变化。镉增加肝脏和肾脏中 DNA 甲基化和 DNMT1 和 DNMT3a mRNA 的表达这一事实表明，DNA 甲基化可能参与了镉的致癌作用。
