title: Analysis of hprt mutations occurring in human TK6 lymphoblastoid cells following exposure to 1,2,3,4-diepoxybutane.
abstract: 1,3-Butadiene (BD) is a rodent carcinogen that is bioactivated to at least two genotoxic metabolites, 1,2-epoxybutene (EB) and 1,2,3,4-diepoxybutane (DEB). The mutational spectrum for DEB at hprt in human TK6 lymphoblasts (TK6 cells) was determined and compared with the mutational spectrum from spontaneous mutants. A DEB exposure of 4 microM for 24 h resulted in an average 5-fold increase in the hprt mutant frequency. Hprt mutants for molecular analysis were isolated from TK6 cells exposed to 4 microM DEB for 24 h (51 DEB-induced mutants) and from a set of spontaneous mutants (n = 43) isolated from the same TK6 stock cell cultures. Molecular analyses of hprt mutations were done by reverse transcription-polymerase chain reaction (RT-PCR) of hprt mRNA or exon-specific genomic PCR amplification of hprt followed by DNA sequencing of PCR products. There was an increased frequency of A:T-->T:A transversions among the DEB-induced mutants compared to spontaneous mutants (9/51; 18% DEB-induced compared to 2/43; 5% in spontaneous (one-way Fisher's exact test; P < or = 0.05). DEB-induced hprt mutants also had an increased frequency of genomic deletions affecting the 5' region of hprt (7/51; 14% DEB-induced compared to 1/43; 2% in spontaneous). Therefore, DEB is a mutagenic carcinogen that can induce genotoxicity by large deletions, rearrangements or single base substitution mutations.
authors.affiliation: Chemical Industry Institute of Toxicology, Research Triangle Park, NC 27709, USA.
authors.forename: A M
authors.initials: AM
authors.lastname: Steen
authors.forename: K G
authors.initials: KG
authors.lastname: Meyer
authors.forename: L
authors.initials: L
authors.lastname: Recio
mesh_terms: D001482:Base Composition; D002273:Carcinogens / Q000633:toxicity; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D004252:DNA Mutational Analysis / Q000379:methods / Q000706:statistics & numerical data; D004251:DNA Transposable Elements; D004587:Electrophoresis, Agar Gel; D004852:Epoxy Compounds / Q000633:toxicity*; D005091:Exons; D006801:Humans; D007041:Hypoxanthine Phosphoribosyltransferase / Q000187:drug effects* / Q000235:genetics*; D008214:Lymphocytes / Q000166:cytology / Q000187:drug effects*; D009153:Mutagens / Q000633:toxicity; D009154:Mutation; D016133:Polymerase Chain Reaction / Q000379:methods; D012326:RNA Splicing / Q000187:drug effects; D012333:RNA, Messenger / Q000187:drug effects; D017384:Sequence Deletion
chemical_list: D002273:Carcinogens; D004251:DNA Transposable Elements; D004852:Epoxy Compounds; D009153:Mutagens; D012333:RNA, Messenger; C007366:diepoxybutane; D007041:Hypoxanthine Phosphoribosyltransferase