Department of Medicinal Chemistry and Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Anal Chem. 2012 Feb 7;84(3):1732-9. doi: 10.1021/ac203079c. Epub 2012 Jan 26.
1,3-Butadiene (BD) is an important industrial chemical and a common environmental pollutant present in urban air. BD is classified as a human carcinogen based on epidemiological evidence for an increased incidence of leukemia in workers occupationally exposed to BD and its potent carcinogenicity in laboratory mice. A diepoxide metabolite of BD, 1,2,3,4-diepoxybutane (DEB), is considered the ultimate carcinogenic species of BD due to its ability to form genotoxic DNA-DNA cross-links. We have previously employed capillary HPLC-ESI(+)-MS/MS (liquid chromatography-electrospray ionization tandem mass spectrometry) methods to quantify DEB-induced DNA-DNA conjugates, e.g. 1,4-bis-(guan-7-yl)-2,3-butanediol (bis-N7G-BD), 1-(guan-7-yl)-4-(aden-1-yl)-2,3-butanediol (N7G-N1A-BD), and 1,N(6)-(1-hydroxymethyl-2-hydroxypropan-1,3-diyl)-2'-deoxyadenosine (1,N(6)-HMHP-dA), in tissues of laboratory mice exposed to 6.25-625 ppm BD (Goggin et al. Cancer Res. 2009, 69(6), 2479-2486). However, typical BD human exposure levels are 0.01 to 3.2 ppb in urban air and 1-2.0 ppm in an occupational setting, requiring greater detection sensitivity for these critical lesions. In the present study, a nanoHPLC-nanoESI(+)-MS/MS method was developed for ultrasensitive, accurate, and precise quantitation of bis-N7G-BD in tissues of laboratory mice treated with low ppm and subppm concentrations of BD. The LOD value of the new method is 0.5 fmol/100 μg DNA, and the LOQ is 1.0 fmol/100 μg DNA, making it possible to quantify bis-N7G-BD adducts present at concentrations of 3 per 10(9) nucleotides. Bis-N7G-BD adduct amounts in liver tissues of mice exposed to 0.5, 1.0, and 1.5 ppm BD for 2 weeks were 5.7 ± 3.3, 9.2 ± 1.5, and 18.6 ± 6.9 adducts per 10(9) nucleotides, respectively, suggesting that bis-N7G-BD adduct formation is more efficient under low exposure conditions. To our knowledge, this is the first quantitative analysis of DEB specific DNA adducts following low ppm and subppm exposure to BD.
1,3-丁二烯（BD）是一种重要的工业化学品，也是城市空气中常见的污染物。BD 被归类为人类致癌物，这是基于职业暴露于 BD 的工人中白血病发病率增加的流行病学证据，以及其在实验小鼠中的强致癌性。BD 的一种环氧化物代谢物，1,2,3,4-二环氧丁烷（DEB），被认为是 BD 的最终致癌物质，因为它能够形成致突变的 DNA-DNA 交联。我们之前曾采用毛细管 HPLC-ESI(+)-MS/MS（液相色谱-电喷雾串联质谱）方法来定量 DEB 诱导的 DNA-DNA 加合物，例如 1,4-双（鸟嘌呤-7-基）-2,3-丁二醇（双-N7G-BD）、1-（鸟嘌呤-7-基）-4-（腺嘌呤-1-基）-2,3-丁二醇（N7G-N1A-BD）和 1,N(6)-(1-羟甲基-2-羟丙基-1,3-二基)-2'-脱氧腺苷（1,N(6)-HMHP-dA），在暴露于 6.25-625 ppm BD 的实验小鼠组织中（Goggin 等人，Cancer Res. 2009, 69(6), 2479-2486）。然而，典型的 BD 人体暴露水平在城市空气中为 0.01 至 3.2 ppb，在职业环境中为 1-2.0 ppm，这需要对这些关键病变进行更高的检测灵敏度。在本研究中，开发了一种纳升 HPLC-纳升 ESI(+)-MS/MS 方法，用于对暴露于低 ppm 和亚 ppm BD 浓度的实验小鼠组织中的双-N7G-BD 进行超灵敏、准确和精密的定量分析。新方法的检测限为 0.5 fmol/100 μg DNA，定量限为 1.0 fmol/100 μg DNA，使能够对 3 个/10^9 个核苷酸浓度的双-N7G-BD 加合物进行定量。暴露于 0.5、1.0 和 1.5 ppm BD 2 周的小鼠肝组织中的双-N7G-BD 加合物含量分别为 5.7 ± 3.3、9.2 ± 1.5 和 18.6 ± 6.9 个/10^9 个核苷酸，表明在低暴露条件下双-N7G-BD 加合物的形成效率更高。据我们所知，这是首次对低 ppm 和亚 ppm BD 暴露后 DEB 特异性 DNA 加合物进行定量分析。
