Quantitation of pyridylhydroxybutyl-DNA adducts in liver and lung of F-344 rats treated with 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and enantiomers of its metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol
Quantitation of pyridylhydroxybutyl-DNA adducts in liver and lung of F-344 rats treated with 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and enantiomers of its metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol
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DOI：
10.1021/tx8001109
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发表时间：
2008-07-01
影响因子：
4.1
通讯作者：
Hecht, Stephen S.
中科院分区：
文献类型：
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作者：
Upadhyaya, Pramod;Kalscheuer, Stephen;Hecht, Stephen S.
烟草特有的亚硝胺4-（甲基亚硝胺）-1-（3-吡啶基）-1-丁酮（NNK）是一种强有力的大鼠肺致癌物，被认为是吸烟者肺癌的原因之一。NNK被代谢为4-（甲基亚硝胺基）-1-（3-吡啶基）-1-丁醇（NNAL），这也是一种强的大鼠肺癌致癌物，在其1-碳上有一个手性中心。先前的研究表明，细胞色素P450催化的NNK在肺中的α-羟基化导致甲基和吡啶氧丁基（POB）-DNA加合物的形成，这对其致癌性至关重要。NNAL的α-羟基化将类似地产生吡啶基羟基丁基（PHB）-DNA加合物，但这些以前没有在体内研究过。POB-和PHB-DNA加合物水平可以指示在任何给定点存在于NNK-或NNAL-处理的大鼠的组织中的吡啶基氧代丁基化和吡啶基羟基丁基化试剂的量。因此，在这项研究中，我们开发了一种灵敏的定量液相色谱-电喷雾电离-串联质谱-选择反应监测方法，以确定PHB-DNA加合物O-6-[4-（3-吡啶基）-4-羟基丁-1-基]-2 '-脱氧鸟苷（O-6-PHB-dGuo，10 b），O-2- [4-（2-羟基苯基）-1-甲基-2-氧代-2（3-吡啶基）-4-羟基丁-1-基]胸苷（O-2-PHB-dThd，11b）和7-[4-（3-吡啶基）-4-羟基丁-1-基]-2 '-脱氧鸟苷（7-PHB-dGuo，12 b），后者作为相应的碱基7-[4-（3-吡啶基）-4-羟基丁-1-基]-胍从在饮用水中用10 ppm NNK、（S）-NNAL或（R）-NNAL处理20周的大鼠的肝和肺分离的DNA中的（7-PHB-Gua，14 b），5、10、16和20周。在每个时间点，肺中的PHB-DNA加合物水平高于肝中的PHB-DNA加合物水平，这与先前在饮用水中用NNK和NNAL处理的大鼠中的POB-DNA加合物的研究一致。结果表明，NNK和（S）-NNAL的行为方式相似，而（R）-NNAL则截然不同。在用NNK或（S）-NNAL处理的大鼠中，在每个时间点的每种加合物的水平在肺中显著相似，并且O-2-PHB-dThd的水平通常大于7-PHB-Gua > O-6- PHB-dGuo。在用（R）NNAL处理的大鼠的肺和肝脏中发现最高的PHB-DNA加合物水平，这表明存在有效催化该化合物的α-甲基羟基化的细胞色素P450。本研究的结果进一步支持了我们的假设，即（S）-NNAL由NNK快速形成，在肺中的未知部位隔离，然后释放并再氧化为NNK，随后形成DNA加合物，导致肺致癌性。
The tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is a potent pulmonary carcinogen in rats and is believed to be one cause of lung cancer in smokers. NNK is metabolized to 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), which is also a strong lung carcinogen in rats and has a chiral center at its 1-carbon. Previous studies have demonstrated that cytochrome P450-catalyzed alpha-hydroxylation of NNK in the lung leading to the formation of methyl and pyridyloxobutyl (POB)-DNA adducts is critical for its carcinogenicity. alpha-Hydroxylation of NNAL would similarly produce pyridylhydroxybutyl (PHB)-DNA adducts, but these have not been previously investigated in vivo. POB- and PHB-DNA adduct levels can indicate the amounts of pyridyloxobutylating and pyridylhydroxybutylating agents present in tissues of NNK- or NNAL-treated rats at any given point. Therefore, in this study, we developed a sensitive and quantitative liquid chromatography-electrospray ionization-tandem mass spectrometry- selected reaction monitoring method to determine levels of the PHB-DNA adducts O-6-[4-(3-pyridyl)-4-hydroxybut-1-yl]-2'-deoxyguanosine (O-6-PHB-dGuo, 10b), O-2- [4-(3-pyridyl)-4-hydroxybut-1-yl]thymidine (O-2-PHB-dThd, 11b), and 7-[4-(3-pyridyl)-4-hydroxybut-1-yl]-2'-deoxyguanosine (7-PHB-dGuo, 12b), the latter as the corresponding base 7-[4-(3-pyridyl)-4hydroxybut-1-yl]-Gua (7-PHB-Gua, 14b) in DNA isolated from liver and lung of rats treated with 10 ppm NNK, (S)-NNAL, or (R)-NNAL in the drinking water for 20 weeks and sacrificed at 1, 2, 5, 10, 16, and 20 weeks. PHB-DNA adduct levels were higher in lung than in liver at each time point, consistent with previous studies of POB-DNA adducts in rats treated with NNK and NNAL in the drinking water. The results showed that NNK and (S)-NNAL behaved in a similar fashion, while (R)-NNAL was strikingly different. In the rats treated with NNK or (S)-NNAL, levels of each adduct at each time point were remarkably similar in lung, and levels of O-2-PHB-dThd were generally greater than 7-PHB-Gua > O-6- PHB-dGuo. The highest PHB-DNA adduct levels were found in lung and liver of rats treated with (R)NNAL, suggesting that there are cytochrome P450s that efficiently catalyze the alpha-methyl hydroxylation of this compound. The results of this study provide further support for our hypothesis that (S)-NNAL is rapidly formed from NNK, sequestered at an unknown site in the lung, and then released and reoxidized to NNK with consequent DNA adduct formation resulting in lung carcinogenicity.