Department of Drug Metabolism and Molecular Toxicology, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences.
J Toxicol Sci. 2019;44(10):693-699. doi: 10.2131/jts.44.693.
Cigarette smoking is a risk factor for the development of various cancers, such as lung, nasal, liver and bladder cancers. 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), a tobacco-specific nitrosamine, is implicated in human lung cancer. NNK-induced DNA adducts are found in target tissues for NNK carcinogenesis. NNK is activated by cytochrome P450 dependent α-hydroxylation at either the methylene carbon or methyl carbon adjacent to the N-nitroso group. The former leads to the formation of the methylating agent, and the latter produce the pyridyloxobutylating agent. NNK and some of its metabolites are further metabolized by UDP-glucuronosyltransferases (UGTs). Glucuronides generally are much less active than the parent aglycon therefore the glucuronides of NNK-related metabolites are thought to be inactive. However, 4-(hydroxymethylnitrosamino)-1-(3-pyridyl)-1-butanone glucuronide (HO-methyl NNK glucuronide) can be transported to the target organs of NNK carcinogenesis where subsequent hydrolysis causes the release of the reactive intermediate. Regeneration of HO-methyl NNK could play an important role in the tissue-specific carcinogenicity of NNK. In the present study, we investigated the reactivity of HO-methyl NNK glucuronide toward 2'-deoxyguanosine (dGuo) and N-acetylcysteine (NAC; used as a models for thiol groups on proteins). The reaction mixtures of HO-methyl NNK glucuronide and dGuo or NAC were analyzed by LCMS-IT-TOF-MS. We also employed 4-(acetoxymethylnitrosamino)-1-(3-pyridyl)-1-butanone, a pyridyloxobutylating agent, to confirm the formation of pyridyloxobutylated adducts. Thus, we determined the production of pyridyloxobutylated dGuo and NAC adducts. Our results suggest HO-methyl NNK glucuronide could generate a reactive intermediate in the tissues and then form adducts with proteins and DNA.
吸烟是多种癌症发展的一个风险因素，如肺癌、鼻癌、肝癌和膀胱癌。4-（甲基亚硝氨基）-1-（3-吡啶基）-1-丁酮（NNK），一种烟草特异性亚硝胺，与人类肺癌有关。NNK 诱导的 DNA 加合物在 NNK 致癌作用的靶组织中被发现。NNK 通过细胞色素 P450 依赖性 α-羟化作用在亚硝氨基基团相邻的亚甲基碳或甲基碳上被激活。前者导致形成甲基化剂，后者产生吡啶氧丁基化剂。NNK 和其一些代谢物进一步被 UDP-葡糖醛酸基转移酶（UGTs）代谢。葡糖醛酸苷通常比母体苷元活性低得多，因此 NNK 相关代谢物的葡糖醛酸苷被认为是无活性的。然而，4-（羟甲基亚硝氨基）-1-（3-吡啶基）-1-丁酮葡糖醛酸苷（HO-甲基 NNK 葡糖醛酸苷）可以被转运到 NNK 致癌作用的靶器官，随后的水解导致活性中间产物的释放。HO-甲基 NNK 的再生可能在 NNK 的组织特异性致癌性中发挥重要作用。在本研究中，我们研究了 HO-甲基 NNK 葡糖醛酸苷与 2'-脱氧鸟苷（dGuo）和 N-乙酰半胱氨酸（NAC；用作蛋白质上巯基的模型）的反应性。通过 LCMS-IT-TOF-MS 分析 HO-甲基 NNK 葡糖醛酸苷与 dGuo 或 NAC 的反应混合物。我们还使用 4-（乙酰氧基甲基亚硝氨基）-1-（3-吡啶基）-1-丁酮，一种吡啶氧丁基化剂，来确认吡啶氧丁基化加合物的形成。因此，我们确定了吡啶氧丁基化 dGuo 和 NAC 加合物的生成。我们的结果表明，HO-甲基 NNK 葡糖醛酸苷可以在组织中产生活性中间体，然后与蛋白质和 DNA 形成加合物。
