Quantitative analysis of 1,3-butadiene‐induced DNA adducts in vivo and in vitro using liquid chromatography electrospray ionization tandem mass spectrometry

Abstract

1,3-Butadiene (BD) is a high volume industrial chemical which is known as a multi-site rodent carcinogen and is classified as a probable human carcinogen. Covalent interactions of the reactive epoxy metabolites of BD with DNA lead to the formation of DNA adducts which may cause mutations and tumor formation. In the present work, liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) was employed for analyses of BD-induced DNA adducts in vitro and in vivo. Selected reaction monitoring (SRM) using the fragmentation of the [M + H]+ ions of the adducts to the corresponding protonated nucleobases under collision-induced dissociation was performed. Quantitation was based on isotope dilution with 13C- and 15N-labeled internal standards. The methods were applied in vitro [calf thymus DNA and TK6 cell cultures treated with epoxy metabolites of BD, 3,4-epoxy-1-butene (EB) and diepoxybutane (DEB)] and in vivo [DNA isolated from tissues of BD-exposed laboratory animals]. Two regioisomers of N-7-EB-guanine adducts, N-7-(2-hydroxy-3-buten-1-yl)guanine (N-7-EB-Gua I) and N-7-(1-hydroxy-3-buten-2-yl)guanine (N-7-EB-Gua II) and two N-3-EB-adenine isomers, N-3-(2-hydroxy-3-buten-1-yl)adenine and N-3-(1-hydroxy-3-buten-2-yl)adenine (N-3-EB-Ade I and II), were found in EB-exposed samples. N-7-(2',3',4'-trihydroxybut-1'-yl)guanine (N-7-THB-Gua), N6-(2',3',4'-trihydroxybut-1'-yl)adenine (N6-THB-Ade), and N-3-(2',3',4'-trihydroxybut-1'-yl)adenine (N-3-THB-Ade) were detected in DEB-treated DNA. DNA isolated from liver and lung of rats and mice exposed to 1250 ppm BD for 2 weeks contained both regioisomers of N-7-EB-Gua and N-3-EB-Ade, as well as N-7-THB-Gua and N6-THB-Ade. The methods developed in this work provide the means to study accumulation, repair and dose-response relationships of BD-DNA adducts in vivo. Although less sensitive than gas chromatography/electron capture negative ionization high-resolution mass spectrometry (GC/ECNI-HRMS), LC/ESI(+)-MS/MS in the SRM mode is extremely useful for analysis of BD-DNA adducts, which are not amenable to GC and derivatization owing to the presence of several adjacent polar functional groups. Using LC/ESI-MS/MS and isotope dilution, multiple structurally diverse BD-DNA adducts can be analyzed simultaneously in the same sample with minimal sample preparation.

Molecular Dosimetry of N-7 Guanine Adduct Formation in Mice and Rats Exposed to 1,3-Butadiene

“…Adducts induced by BD were assessed in skin DNA of mice treated with 1.9-153 µmol of DEB per mouse (43). The amounts of EB-Gua and THB-Gua adducts have been quantitated in livers of female B6C3F1 mice and female F344 rats exposed to 1250 ppm BD by inhalation for 10 days (41,46,47) and in lungs of female B6C3F1 mice (41).…”

“…The N-7 guanine adducts of EB (24)(25)(26)(27)(28)(29)(30)(31) and DEB (32), N-1, N-3, N 6 , and N-7 adenine adducts of EB (30,31,(33)(34)(35), and N-3, N 6 , N-7, and N-9 adenine adducts of DEB (36)(37)(38) and N-3-thymidine adducts of EB (39) have been characterized. LC/ESI + /MS/MS (40,41) and 32 P-postlabeling (27,28,34,35,37,(42)(43)(44)(45) combined with chromatographic separation have been used to characterize and/or quantitate the adducts formed in vitro by EB and DEB. There have also been several reports of BD-induced adduct formation in vivo.…”

Analysis of DNA-bound advanced glycation end-products by LC and mass spectrometry

“…For chromatographic separation of the modified nucleosides and nucleobases, usually reversed phase columns with RP-18 or RP-8 stationary phases are applied [24,27,53,57]. The adducts are commonly eluted with aqueous phase-acetonitrile gradients [24,27,57,58]. In some cases, methanol is used instead of acetonitrile [54], but the formation of artifact adducts from methanol has been described [59].…”

1,3-Butadiene: Exposure Estimation, Hazard Characterization, and Exposure-Response Analysis

“…With respect to effects on somatic cells, although butadiene was mutagenic at the hprt locus in both mice and rats (Cochrane & Skopek, 1993, 1994Tates et al, 1994Tates et al, , 1998Meng et al, 1998Meng et al, , 2000, its mutagenic potency was greater in mice (Meng et al, 1998(Meng et al, , 2000. Other manifestations of genotoxicity (chromosomal aberrations, sister chromatid exchanges, micronuclei, and DNA binding or damage) were noted in somatic cells of mice but not in those of rats exposed to much higher concentrations Cunningham et al, 1986;Irons et al, 1986aIrons et al, , 1986bIrons et al, , 1987Kreiling et al, 1986;Tice et al, 1987;Jauhar et al, 1988;Arce et al, 1990;Shelby, 1990;Victorin et al, 1990;NTP, 1993;Przygoda et al, 1993;Vangala et al, 1993;Adler et al, 1994;Autio et al, 1994;Walles et al, 1995;Sorsa et al, 1996;Anderson et al, 1997;Koivisto et al, 1997Koivisto et al, , 1998Leavens et al, 1997;Stephanou et al, 1998;Tretyakova et al, 1998aTretyakova et al, , 1998b. However, unlike the observations with the parent compound, there is little evidence of species differences in the sensitivity to genotoxic effects in somatic or germ cells induced by the epoxide metabolites of butadiene (EB, DEB, and EBdiol), although there was some indication of interstrain variability (Conner et al, 1983;Sharief et al, 1986;Walk et al, 1987;…”