title: Mutations induced by 1,3-butadiene metabolites, butadiene diolepoxide, and 1,2,3,4-diepoxybutane at the Hprt locus in CHO-K1 cells.
abstract: Butadiene (BD) is an important industrial chemical that is classified as a probable human carcinogen. Butadiene diolepoxide (BDE) and 1,2,3,4-diepoxybutane (DEB) are metabolites of carcinogenic BD and contain the DNA-reactive one and two epoxides, respectively. In this study, the mutation frequencies and mutation spectra that are induced by BDE and DEB have been investigated at the hprt locus in CHO-K1 cells. The BDE- and DEB-treated CHO-K1 cells were allowed to grow for several days, then seeded in a medium that contained 6-thioguanine in order to select the hprt mutants. BDE exhibited the mutagenic activity at concentrations that were approximately 100-times higher than DEB. The mutation spectra for BDE and DEB were determined by a reverse transcription-polymerase chain reaction of hprt mRNA, which was followed by automatic DNA sequencing of the PCR products. The mutational spectrum for BDE was exon deletions (16/41), G x C --> A x T transitions (11/41), and A x T --> G x C transitions (5/41). The mutational spectrum for DEB was exon deletions (15/39), G x C --> A x T transitions (11/39), and A x T --> T x A transversions (5/39). The most common base substitution that was induced by both BDE and DEB was G x C --> A x T transitions. The sites of the single base substitutions that were induced by BDE and DEB were guanine and adenine, which was consistent with the DNA adduct profiles. The high frequencies of the exon deletions by each metabolite occurred in the regions of exons 2, 3, or 4. These data indicate that BDE and DEB are mutagenic carcinogens by forming DNA adducts at the site of adenine and guanine, and inducing large exon deletions and single base substitutions.
authors.affiliation: Department of Biochemistry and Institute of Natural Sciences, College of Natural Sciences, Yeungnam University, Kyongsan 712-749, Korea.
authors.forename: Dong-Hyun
authors.initials: DH
authors.lastname: Lee
authors.forename: Tae-Ho
authors.initials: TH
authors.lastname: Kim
authors.forename: Sun-Young
authors.initials: SY
authors.lastname: Lee
authors.forename: Hyun-Jo
authors.initials: HJ
authors.lastname: Kim
authors.forename: Seung Keun
authors.initials: SK
authors.lastname: Rhee
authors.forename: ByoungSu
authors.initials: B
authors.lastname: Yoon
authors.forename: Gerd P
authors.initials: GP
authors.lastname: Pfeifer
authors.forename: Chong-Soon
authors.initials: CS
authors.lastname: Lee
mesh_terms: D000818:Animals; D002070:Butadienes / Q000633:toxicity*; D016466:CHO Cells / Q000187:drug effects* / Q000201:enzymology; D002273:Carcinogens / Q000633:toxicity*; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D006224:Cricetinae; D018736:DNA Adducts; D004249:DNA Damage; D004252:DNA Mutational Analysis / Q000379:methods; D017931:DNA Primers / Q000737:chemistry; D004852:Epoxy Compounds / Q000633:toxicity*; D005091:Exons; D005562:Formazans; D006018:Glycols; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics*; D016296:Mutagenesis; D009153:Mutagens / Q000633:toxicity*; D009154:Mutation; D016133:Polymerase Chain Reaction; D017384:Sequence Deletion; D013778:Tetrazolium Salts
chemical_list: D002070:Butadienes; D002273:Carcinogens; D018736:DNA Adducts; D017931:DNA Primers; D004852:Epoxy Compounds; D005562:Formazans; D006018:Glycols; D009153:Mutagens; D013778:Tetrazolium Salts; C080053:3,4-epoxybutane-1,2-diol; C079782:MTT formazan; C007366:diepoxybutane; D007041:Hypoxanthine Phosphoribosyltransferase