Cellular Repair of DNA-DNA Cross-Links Induced by 1,2,3,4-Diepoxybutane

Int J Mol Sci. 2017 May 18;18(5):1086. doi: 10.3390/ijms18051086.

Abstract

Xenobiotic-induced interstrand DNA-DNA cross-links (ICL) interfere with transcription and replication and can be converted to toxic DNA double strand breaks. In this work, we investigated cellular responses to 1,4-bis-(guan-7-yl)-2,3-butanediol (bis-N7G-BD) cross-links induced by 1,2,3,4-diepoxybutane (DEB). High pressure liquid chromatography electrospray ionization tandem mass spectrometry (HPLC-ESI⁺-MS/MS) assays were used to quantify the formation and repair of bis-N7G-BD cross-links in wild-type Chinese hamster lung fibroblasts (V79) and the corresponding isogenic clones V-H1 and V-H4, deficient in the XPD and FANCA genes, respectively. Both V-H1 and V-H4 cells exhibited enhanced sensitivity to DEB-induced cell death and elevated bis-N7G-BD cross-links. However, relatively modest increases of bis-N7G-BD adduct levels in V-H4 clones did not correlate with their hypersensitivity to DEB. Further, bis-N7G-BD levels were not elevated in DEB-treated human clones with defects in the XPA or FANCD2 genes. Comet assays and γ-H2AX focus analyses conducted with hamster cells revealed that ICL removal was associated with chromosomal double strand break formation, and that these breaks persisted in V-H4 cells as compared to control cells. Our findings suggest that ICL repair in cells with defects in the Fanconi anemia repair pathway is associated with aberrant re-joining of repair-induced double strand breaks, potentially resulting in lethal chromosome rearrangements.

Keywords: 1,2,3,4-diepoxybutane; Chinese hamster lung fibroblast; DNA double strand break; DNA repair; Fanconi anemia; homologous recombination; interstrand DNA-DNA crosslink; nucleotide excision repair.

MeSH terms

  • Animals
  • Cell Line
  • Cricetinae
  • DNA Breaks, Double-Stranded / drug effects
  • DNA Repair / drug effects
  • DNA Repair / genetics*
  • Epoxy Compounds / pharmacology*
  • Fanconi Anemia / genetics
  • Fanconi Anemia Complementation Group D2 Protein / genetics
  • Xeroderma Pigmentosum Group A Protein / genetics

Substances

  • Epoxy Compounds
  • Fanconi Anemia Complementation Group D2 Protein
  • Xeroderma Pigmentosum Group A Protein
  • diepoxybutane