Identification of an acetaldehyde adduct in human liver DNA and quantitation as N2-ethyldeoxyguanosine
Identification of an acetaldehyde adduct in human liver DNA and quantitation as N2-ethyldeoxyguanosine
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DOI：
10.1021/tx0502948
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发表时间：
2006-02-01
影响因子：
4.1
通讯作者：
Hecht, SS
中科院分区：
文献类型：
--
作者：
Wang, MY;Yu, NX;Hecht, SS
乙醛是一种普遍存在的诱变剂和致癌物，可能与人类癌症病因有关。由于 DNA 加合物在致癌作用中很重要，因此我们使用液相色谱-电喷雾电离-串联质谱 (LC-ESI-MS/MS) 来探索人肝脏 DNA 中主要乙醛 DNA 加合物 N-2-亚乙基脱氧鸟苷 (1) 的存在情况 (1)。分离 DNA 并在 NaBH3CN 存在下进行酶水解，将加合物 1 定量转化为 N-2-乙基脱氧鸟苷 (N-2-乙基-dGuo, 2)。合成[N-15(5)]N-2-乙基-dGuo 并用作内标。通过固相萃取从水解产物中富集加合物 2，并通过 LC-ESI-MS/MS 进行分析。在人肝脏 DNA、小牛胸腺 DNA 和大鼠肝脏 DNA 分析中，观察到加合物 2 的清晰峰。当省略 NaBH3CN 步骤时，没有观察到这些峰，或者这些峰小得多。当在 NaBH3CN 处理之前对 DNA 进行中性热水解时，没有观察到加合物 2。使用[C-13(2)]乙醛的对照实验表明，在DNA分离和分析过程中，加合物1和2并未作为伪影形成。这些结果强烈表明，加合物 1 存在于人肝脏 DNA 中，并证明它可以作为加合物 2 进行定量。在 12 个人肝脏样品中测得的加合物 2 水平为 534 +/- 245 fmol/mu mol dGuo（平均值 +/- SD）。这项研究的结果证实了人类肝脏 DNA 中存在乙醛加合物，并表明它是一种常见的内源性 DNA 加合物。
Acetaldehyde, an ubiquitous mutagen and carcinogen, could be involved in human cancer etiology. Because DNA adducts are important in carcinogenesis, we have used liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) to explore the presence in human liver DNA of the major acetaldehyde DNA adduct, N-2-ethylidenedeoxyguanosine (1). DNA was isolated and enzymatically hydrolyzed in the presence of NaBH3CN, which quantitatively converts adduct 1 to N-2-ethyldeoxyguanosine (N-2-ethyl-dGuo, 2). [N-15(5)]N-2-Ethyl-dGuo was synthesized and used as an internal standard. Adduct 2 was enriched from the hydrolysate by solid phase extraction and analyzed by LC-ESI-MS/MS. Clear peaks were observed for adduct 2 in analyses of human liver DNA, calf thymus DNA, and rat liver DNA. These peaks were not observed, or were much smaller, when the NaBH3CN step was ommitted. When the DNA was subjected to neutral thermal hydrolysis prior to NaBH3CN treatment, adduct 2 was not observed. Control experiments using [C-13(2)]acetaldehyde demonstrated that adducts 1 and 2 were not formed as artifacts during DNA isolation and analysis. These results strongly indicate that adduct 1 is present in human liver DNA and demonstrate that it can be quantified as adduct 2. Levels of adduct 2 measured in 12 human liver samples were 534 +/- 245 fmol/mu mol dGuo (mean +/- SD). The results of this study establish the presence of an acetaldehyde adduct in human liver DNA and suggest that it is a commonly occurring endogenous DNA adduct.