2-amino-3,8-dimethylimidazo-[4,5-f]quinoxaline-induced DNA adduct formation and mutagenesis in DNA repair-deficient Chinese hamster ovary cells expressing human cytochrome P4501A1 and rapid or slow acetylator N-acetyltransferase 2
2-amino-3,8-dimethylimidazo-[4,5-f]quinoxaline-induced DNA adduct formation and mutagenesis in DNA repair-deficient Chinese hamster ovary cells expressing human cytochrome P4501A1 and rapid or slow acetylator N-acetyltransferase 2
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DOI：
10.1158/1055-9965.epi-07-0305
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发表时间：
2007-07-01
影响因子：
3.8
通讯作者：
Hein, David W.
中科院分区：
文献类型：
--
作者：
Bendaly, Jean;Zhao, Shuang;Hein, David W.
2-氨基-3，8-二甲基咪唑并[4，5-f]喹喔啉（MeIQx）是西方饮食中最有效和最丰富的诱变剂之一。生物活化包括由细胞色素P450催化的N-羟基化，随后由N-乙酰转移酶2（NAT 2）催化的O-乙酰化。在人类中，NAT 2 *4等位基因与快速乙酰化表型相关，而NAT 2 * 5 B等位基因与缓慢乙酰化表型相关。我们假设快速乙酰化表型使人类易于受到MeIQx的DNA损伤和诱变。通过稳定转染人细胞色素P4501 A1（CYP 1A 1）和单拷贝NAT 2 *4（快速乙酰化）或NAT 2 * 5 B（缓慢乙酰化）等位基因构建核苷酸切除修复缺陷型中国仓鼠卵巢细胞。在未转染的中国仓鼠卵巢细胞系中未检测到CYP 1A 1和NAT 2催化活性。CYP 1A 1基因转染细胞株之间的CYP 1A 1活性无显著性差异（P > 0.05）。与用NAT 2 * 5 B转染的细胞相比，用NAT 2 *4转染的细胞具有20倍显著更高水平的磺胺二甲嘧啶N-乙酰转移酶（P = 0.0001）和6倍更高水平的N-羟基-MeIQx O-乙酰转移酶（P = 0.0093）催化活性。只有同时转染CYP 1A 1和NAT 2 *4的细胞在MeIQx处理后显示出浓度依赖性细胞毒性和次黄嘌呤磷酸核糖转移酶诱变。脱氧鸟苷-C8-MeIQx是形成的主要DNA加合物，在各细胞系中的水平呈剂量依赖性，顺序如下：未转染<CYP 1A 1转染<CYP 1A 1和NAT 2 * 5 B转染<CYP 1A 1和NAT 2 *4转染。在所有检测的MeIQx浓度下，CYP 1A 1/NAT 2 *4细胞中的MeIQx DNA加合物水平均显著高于（P < 0.001）CYP 1A 1/NAT 2 * 5 B细胞。MeIQx诱导的DNA加合物水平与MeIQx诱导的突变体高度相关（r（2）= 0.88）。这些结果强烈支持CYP 1A 1对MeIQx的肝外激活，以及人类NAT 2基因多态性对MeIQx诱导的DNA加合物和诱变的稳健影响。这些结果为流行病学研究提供了实验室支持，这些研究报告了快速NAT 2乙酰化剂中杂环胺相关癌症的发生频率较高。
2-Amino-3,8-dimethylimidazo-[4,5-f]quinoxaline (MeIQx) is one of the most potent and abundant mutagens in the western diet. Bioactivation includes N-hydroxylation catalyzed by cytochrome P450s followed by O-acetylation catalyzed by N-acetyltransferase 2 (NAT2). In humans, NAT2*4 allele is associated with rapid acetylator phenotype, whereas NAT2*5B allele is associated with slow acetylator phenotype. We hypothesized that rapid acetylator phenotype predisposes humans to DNA damage and mutagenesis from MeIQx. Nucleotide excision repair-deficient Chinese hamster ovary cells were constructed by stable transfection of human cytochrome P4501A1 (CYP1A1) and a single copy of either NAT2*4 (rapid acetylator) or NAT2*5B (slow acetylator) alleles. CYP1A1 and NAT2 catalytic activities were undetectable in untransfected Chinese hamster ovary cell lines. CYP1A1 activity did not differ significantly (P > 0.05) among the CYP1A1-transfected cell lines. Cells transfected with NAT2*4 had 20-fold significantly higher levels of sulfamethazine N-acetyltransferase (P = 0.0001) and 6-fold higher levels of N-hydroxy-MeIQx O-acetyltransferase (P = 0.0093) catalytic activity than cells transfected with NAT2*5B. Only cells transfected with both CYP1A1 and NAT2*4 showed concentration-dependent cytotoxicity and hypoxanthine phosphoribosyl transferase mutagenesis following MeIQx treatment. Deoxyguanosine-C8-MeIQx was the primary DNA adduct formed and levels were dose dependent in each cell line and in the following order: untransfected < transfected with CYP1A1 < transfected with CYP1A1 and NAT2*5B < transfected with CYP1A1 and NAT2*4. MeIQx DNA adduct levels were significantly higher (P < 0.001) in CYP1A1/NAT2*4 than CYP1A1/NAT2*5B cells at all concentrations of MeIQx tested. MeIQx-induced DNA adduct levels correlated 2 very highly (r(2) = 0.88) with MeIQx-induced mutants. These results strongly support extrahepatic activation of MeIQx by CYP1A1 and a robust effect of human NAT2 genetic polymorphism on MeIQx-induced DNA adducts and mutagenesis. The results provide laboratory-based support for epidemiologic studies reporting higher frequency of heterocyclic amine-related cancers in rapid NAT2 acetylators.