Quantification of sulfur mustard-induced DNA interstrand cross-links and single-strand breaks in cultured human epidermal keratinocytes.
The induction of DNA interstrand cross-links and their repair has been studied in cultured human epidermal keratinocytes exposed to sulfur mustard, bis-(beta-chloroethyl)sulfide. Alkaline elution is the most sensitive method to determine the number of DNA interstrand cross-links quantitatively. However, in the case of sulfur mustard the reliability of these data will be less since sulfur mustard also induces DNA single-strand breaks (SSB) and/or alkali-labile sites (ALS). The frequency of SSB and/or ALS induced by sulfur mustard is determined immunochemically. Correction for the induction of SSB and/or ALS induced by sulfur mustard resulted in a substantial increase in the calculated number of cross-links. Our results indicate that per microM sulfur mustard approximately 0.05 SSB (and/or ALS)/10(9) Da of DNA and approximately 0.12 cross-links/10(9) Da of DNA were induced immediately after exposure. Most of the DNA interstrand cross-links are removed during the first 24 h post exposure, but a small number of lesions seem to be persistent. In cells exposed to sulfur mustard concentrations as low as 1 microM, repair seems to occur not at all.
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TNO Medical Biological Laboratory, Rijswijk, The Netherlands.
van der Schans
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Lohman
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D002478:Cells, Cultured; D003432:Cross-Linking Reagents / Q000494:pharmacology*; D004247:DNA / Q000187:drug effects; D004249:DNA Damage; D004260:DNA Repair; D006801:Humans; D015603:Keratinocytes / Q000187:drug effects*; D009151:Mustard Gas / Q000494:pharmacology*
D003432:Cross-Linking Reagents; D004247:DNA; D009151:Mustard Gas