Eagon P K, Teepe A G, Elm M S, Tadic S D, Epley M J, Beiler B E, Shinozuka H, Rao K N
VA Medical Center, Pittsburgh, PA 15240, USA.
Carcinogenesis. 1999 Jun;20(6):1091-6. doi: 10.1093/carcin/20.6.1091.
We previously demonstrated that rats exposed to the peroxisome proliferator (PP) diethylhexylphthalate (DEHP) had reduced serum ceruloplasmin (CP) oxidase activity, which suggests tissue copper deposition. Copper is highly toxic in excess, and results in cellular damage and hepatocellular carcinomas (HCC). This study addresses changes in expression of copper-related genes and metal accumulation in hyperplastic liver and tumors induced by PP. Male rats were fed diets containing DEHP or clofibrate (CLF) for 3-60 days (hyperplasia) and 4-chloro-6-(2,3 xylidino)-2-pyrimidinyl-thio(N-beta-hydroxyethyl) acetamide for 10 months (HCC). During hyperplasia, an immediate and progressive decrease in serum CP activity was observed (P < 0.05), as were reductions in mRNA levels for both CP and Wilson's disease gene (WD gene, a P-type ATPase) (P < 0.05). Tumor-bearing rats had lower serum CP activity (P < 0.05), and CP and WD gene mRNA levels were reduced in tumors (P < 0.05), and in liver surrounding tumors (SL) (P < 0.05). Metallothionein mRNA showed no consistent changes during hyperplasia. Tumors showed a 2.5-fold induction of metallothionein mRNA (P < 0.05), and a 1.2-fold increase in SL. Temporal increases in liver copper content occurred during hyperplasia, with increases of 2-fold (DEHP) and 3.3-fold (CLF) at 60 days (P < 0.05). Copper content was 2.2-fold higher in tumors (P < 0.05) and 1.7-fold higher in SL; iron did not increase and zinc decreased temporally. Thus, copper accumulation and changes in copper-related gene expression may be contributing factors in liver neoplasia in PP-treated rats. Loss of CP results in decreased free radical scavenger capacity and thus may enhance oxidative damage induced by PPs.
我们之前证明，暴露于过氧化物酶体增殖剂（PP）邻苯二甲酸二己酯（DEHP）的大鼠血清铜蓝蛋白（CP）氧化酶活性降低，这表明有组织铜沉积。过量的铜具有高毒性，会导致细胞损伤和肝细胞癌（HCC）。本研究探讨了PP诱导的增生性肝脏和肿瘤中铜相关基因表达的变化以及金属蓄积情况。雄性大鼠喂食含DEHP或氯贝丁酯（CLF）的饲料3至60天（增生期），并喂食4 - 氯 - 6 -（2,3 - 二甲基苯胺基）- 2 - 嘧啶硫基（N - β - 羟乙基）乙酰胺10个月（HCC期）。在增生期，观察到血清CP活性立即且逐渐降低（P < 0.05），CP和威尔逊病基因（WD基因，一种P型ATP酶）的mRNA水平也降低（P < 0.05）。荷瘤大鼠血清CP活性较低（P < 0.05），肿瘤及肿瘤周围肝脏（SL）中CP和WD基因的mRNA水平降低（P < 0.05）。金属硫蛋白mRNA在增生期无一致变化。肿瘤中金属硫蛋白mRNA诱导增加2.5倍（P < 0.05），SL中增加1.2倍。增生期肝脏铜含量随时间增加，在60天时DEHP组增加2倍，CLF组增加3.3倍（P < 0.05）。肿瘤中铜含量高2.2倍（P < 0.05），SL中高1.7倍；铁含量未增加，锌含量随时间降低。因此，铜蓄积和铜相关基因表达变化可能是PP处理大鼠肝脏肿瘤形成的促成因素。CP缺失导致自由基清除能力下降，从而可能增强PP诱导的氧化损伤。
