Guanine−Adenine DNA Cross-Linking by 1,2,3,4-Diepoxybutane:  Potential Basis for Biological Activity

Abstract

1,2,3,4-Diepoxybutane (DEB) is a prominent carcinogenic metabolite of 1,3-butadiene (1,3-BD), an important industrial chemical and an environmental pollutant found in cigarette smoke and automobile exhaust. DEB is capable of inducing a variety of genotoxic effects, including point mutations, large deletions, and chromosomal aberrations. The mutagenicity and carcinogenicity of DEB are thought to result from its ability to form bifunctional DNA-DNA adducts by sequentially alkylating two nucleobases within the DNA double helix. We recently reported that DEB-induced DNA-DNA cross-linking leads to the formation of 1,4-bis-(guan-7-yl)-2,3-butanediol (bis-N7G-BD) adducts [Park, S., and Tretyakova, N. (2004) Structural characterization of the major DNA-DNA cross-link of 1,2,3,4-diepoxybutane. Chem. Res. Toxicol. 17 (2), 129-136]. However, guanine-guanine cross-linking by DEB cannot explain the development of A:T base pair mutations following exposure to DEB and 1,3-BD. In the present work, four asymmetrical DNA-DNA cross-links involving both adenine and guanine nucleobases were identified in double-stranded DNA treated with racemic DEB. These novel lesions were assigned the structures of 1-(aden-1-yl)-4-(guan-7-yl)-2,3-butanediol (N1A-N7G-BD), 1-(aden-3-yl)-4-(guan-7-yl)-2,3-butanediol (N3A-N7G-BD), 1-(aden-7-yl)-4-(guan-7-yl)-2,3-butanediol (N7A-N7G-BD), and 1-(aden-N6-yl)-4-(guan-7-yl)-2,3-butanediol (N6A-N7G-BD), based on the comparison of their MS/MS spectra, HPLC retention times, and UV spectra with those of the corresponding authentic standards prepared independently. Although guanine-adenine lesions are approximately 10 times less abundant in DEB-treated double-stranded DNA than the corresponding bis-N7G cross-links, N1A-N7G-BD and N6A-N7G-BD are more hydrolytically stable and, if formed in vivo, may accumulate in target tissues. HPLC-ESI-MS/MS analysis of guanine-adenine DEB cross-links induced in synthetic DNA duplexes 5'-(GGT)5, 5'-(GT)7G, and 5'-(GAA)5 (+-strand) demonstrate that G-A cross-linking by DEB produces primarily 1,3-interstrand N1A-N7G lesions. The formation of bifunctional guanine-adenine adducts is likely to contribute to AT base pair substitutions and deletion mutations following DEB exposure.

Quantitative High-Performance Liquid Chromatography−Electrospray Ionization−Tandem Mass Spectrometry Analysis of the Adenine−Guanine Cross-Links of 1,2,3,4-Diepoxybutane in Tissues of Butadiene-Exposed B6C3F1 Mice

“…Meso-DEB, unlabeled N7G-N1A-BD, N7G-N3A-BD, N7G-N7A-BD, and N7G-N 6 A-BD were synthesized as previously reported (39). 15 2′-Deoxyadenosine (49.7 mg), 15 N 3 , 13 C 1 -dG (8.8 mg), and glacial acetic acid (1 mL) were combined in a microcentrifuge tube and heated to 80 °C.…”

“…Among these, N7G-N3A-BD and N7G-N7A-BD are thermally labile and can be spontaneously released from the DNA backbone under physiological conditions, while N7G-N1A-BD and N7G-N 6 A-BD require acid hydrolysis to undergo depurination (39). In the present work, we report an HPLC-ESI + -MS/MS method for sensitive and accurate quantitation of adenine-guanine cross-links of DEB in vitro and in vivo and its application to analyses of guanine-adenine (G-A) BD cross-links in liver DNA of BD-exposed and control female B6C3F1 mice.…”

Quantitative Analysis of Trihydroxybutyl Mercapturic Acid, a Urinary Metabolite of 1,3-Butadiene, in Humans

“…17–20 DNA adducts induced by BD exposure include N-7-(2-hydroxy-3-buten-1-yl)guanine, N-7-(1-hydroxy-3-buten-2-yl)guanine, N-7-(2,3,4-trihydroxy-3-buten-2-yl)guanine, 21 1,4- bis -(guan-7-yl)-2,3,-butanediol ( bis -N7G-BD), 22,23 1-(guan-7-yl)-4-(aden-1-yl)-2,3-butanediol (N7G-N1A-BD), 1-(guan-7-yl)-4-(aden-3-yl)-2,3-butanediol(N7G-N3A-BD), and 1-(guan-7-yl)-4-(aden-7-yl)-2,3-butanediol (N7G-N7A-BD). 22 Several BD-induced hemoglobin adducts have been identified, e.g. N -(2-hydroxy-3-buten-1-yl)-valine (HB-Val), 1,2,3-trihydroxybutyl-valine (THB-Val), and N,N -(2,3-dihydroxy-1,4-butadiyl)-valine (Pyr-Val).…”

Synthesis and Characterization of Adducts Formed in the Reactions of Safrole 2′,3′‐Oxide with 2′‐Deoxyadenosine, Adenine, and Calf Thymus DNA

“…[14] However, Guenthner et al have reported that DNA adducts of 2 can be formed in vitro but were not detectable in vivo. [9,15] The structure of 2 is similar to that of many epoxides whose genotoxicity and potential formation of DNA adducts have been well studied, [16][17][18] which led to our interest in purifying and characterizing potential DNA adducts of 2 in vitro.…”

“…[17][18][19][20] For example, allylbenzene 2Ј,3Ј-oxide has been shown to react with 2Ј-deoxyguanosine to form N 2 -(2Ј-hydroxy-3Ј-phenylpropyl)-2Ј-deoxyguanosine. [9] In order to gain more insight into the genotoxicity of 2, we needed to synthesize related DNA adducts as standards.…”