Chen Pei-Jen, Padgett William T, Moore Tanya, Winnik Witold, Lambert Guy R, Thai Sheau-Fung, Hester Susan D, Nesnow Stephen
Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan.
Toxicol Appl Pharmacol. 2009 Jan 15;234(2):143-55. doi: 10.1016/j.taap.2008.10.004. Epub 2008 Oct 29.
Conazoles are fungicides used in agriculture and as pharmaceuticals. In a previous toxicogenomic study of triazole-containing conazoles we found gene expression changes consistent with the alteration of the metabolism of all trans-retinoic acid (atRA), a vitamin A metabolite with cancer-preventative properties (Ward et al., Toxicol. Pathol. 2006; 34:863-78). The goals of this study were to examine effects of propiconazole, triadimefon, and myclobutanil, three triazole-containing conazoles, on the microsomal metabolism of atRA, the associated hepatic cytochrome P450 (P450) enzyme(s) involved in atRA metabolism, and their effects on hepatic atRA levels in vivo. The in vitro metabolism of atRA was quantitatively measured in liver microsomes from male CD-1 mice following four daily intraperitoneal injections of propiconazole (210 mg/kg/d), triadimefon (257 mg/kg/d) or myclobutanil (270 mg/kg/d). The formation of both 4-hydroxy-atRA and 4-oxo-atRA were significantly increased by all three conazoles. Propiconazole-induced microsomes possessed slightly greater metabolizing activities compared to myclobutanil-induced microsomes. Both propiconazole and triadimefon treatment induced greater formation of 4-hydroxy-atRA compared to myclobutanil treatment. Chemical and immuno-inhibition metabolism studies suggested that Cyp26a1, Cyp2b, and Cyp3a, but not Cyp1a1 proteins were involved in atRA metabolism. Cyp2b10/20 and Cyp3a11 genes were significantly over-expressed in the livers of both triadimefon- and propiconazole-treated mice while Cyp26a1, Cyp2c65 and Cyp1a2 genes were over-expressed in the livers of either triadimefon- or propiconazole-treated mice, and Cyp2b10/20 and Cyp3a13 genes were over-expressed in the livers of myclobutanil-treated mice. Western blot analyses indicated conazole induced-increases in Cyp2b and Cyp3a proteins. All three conazoles decreased hepatic atRA tissue levels ranging from 45-67%. The possible implications of these changes in hepatic atRA levels on cell proliferation in the mouse tumorigenesis process are discussed.
三唑类化合物是用于农业和制药的杀菌剂。在之前一项关于含三唑的三唑类化合物的毒理基因组学研究中，我们发现基因表达变化与全反式维甲酸（atRA）代谢的改变一致，atRA是一种具有防癌特性的维生素A代谢产物（沃德等人，《毒理病理学》，2006年；34:863 - 78）。本研究的目的是检测丙环唑、三唑酮和腈菌唑这三种含三唑的三唑类化合物对atRA微粒体代谢、参与atRA代谢的相关肝细胞色素P450（P450）酶以及它们对体内肝脏atRA水平的影响。在雄性CD - 1小鼠连续四天腹腔注射丙环唑（210毫克/千克/天）、三唑酮（257毫克/千克/天）或腈菌唑（270毫克/千克/天）后，定量测定肝脏微粒体中atRA的体外代谢。所有三种三唑类化合物均显著增加了4 - 羟基 - atRA和4 - 氧代 - atRA的生成。与腈菌唑诱导的微粒体相比，丙环唑诱导的微粒体具有稍高的代谢活性。与腈菌唑处理相比，丙环唑和三唑酮处理均诱导了更多4 - 羟基 - atRA的生成。化学和免疫抑制代谢研究表明，参与atRA代谢的是Cyp26a1、Cyp2b和Cyp3a蛋白，而非Cyp1a1蛋白。在三唑酮和丙环唑处理的小鼠肝脏中，Cyp2b10/20和Cyp3a11基因显著过表达，而在三唑酮或丙环唑处理的小鼠肝脏中，Cyp26a1、Cyp2c65和Cyp1a2基因过表达，在腈菌唑处理的小鼠肝脏中，Cyp2b10/20和Cyp3a13基因过表达。蛋白质免疫印迹分析表明三唑类化合物诱导了Cyp2b和Cyp3a蛋白的增加。所有三种三唑类化合物均使肝脏atRA组织水平降低了45% - 67%。本文讨论了肝脏atRA水平的这些变化对小鼠肿瘤发生过程中细胞增殖的可能影响。
