A novel 14C-postlabeling assay using accelerator mass spectrometry for the detection of O6-methyldeoxy-guanosine adducts

Authors

  • Elaine M. Tompkins,

    1. Cancer Biomarkers and Prevention Group, Department of Cancer Studies and Molecular Medicine, The Biocentre, University of Leicester, University Road, Leicester LE1 7RH, UK
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  • Peter B. Farmer,

    1. Cancer Biomarkers and Prevention Group, Department of Cancer Studies and Molecular Medicine, The Biocentre, University of Leicester, University Road, Leicester LE1 7RH, UK
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  • John H. Lamb,

    1. Cancer Biomarkers and Prevention Group, Department of Cancer Studies and Molecular Medicine, The Biocentre, University of Leicester, University Road, Leicester LE1 7RH, UK
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  • Rebekah Jukes,

    1. MRC Toxicology Unit, Hodgkin Building, Lancaster Road, Leicester LE1 9HN, UK
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  • Karen Dingley,

    1. Biosciences Division, Lawrence Livermore National Laboratory, Livermore, CA 94551, USA
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  • Esther Ubick,

    1. Biosciences Division, Lawrence Livermore National Laboratory, Livermore, CA 94551, USA
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  • Kenneth W. Turteltaub,

    1. Biosciences Division, Lawrence Livermore National Laboratory, Livermore, CA 94551, USA
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  • Elizabeth A. Martin,

    1. Cancer Biomarkers and Prevention Group, Department of Cancer Studies and Molecular Medicine, The Biocentre, University of Leicester, University Road, Leicester LE1 7RH, UK
    Current affiliation:
    1. AstraZeneca, Safety Assessment, Alderley Park, Macclesfield SK10 4TG, UK.
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  • Karen Brown

    Corresponding author
    1. Cancer Biomarkers and Prevention Group, Department of Cancer Studies and Molecular Medicine, The Biocentre, University of Leicester, University Road, Leicester LE1 7RH, UK
    • Cancer Biomarkers and Prevention Group, Department of Cancer Studies and Molecular Medicine, The Biocentre, University of Leicester, University Road, Leicester LE1 7RH, UK.
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Abstract

Accelerator mass spectrometry (AMS) is currently one of the most sensitive methods available for the trace detection of DNA adducts and is particularly valuable for measuring adducts in humans or animal models. However, the standard approach requires administration of a radiolabeled compound. As an alternative, we have developed a preliminary 14C-postlabeling assay for detection of the highly mutagenic O6-methyldeoxyguanosine (O6-MedG), by AMS. Procedures were developed for derivatising O6-MedG using unlabeled acetic anhydride. Using conventional liquid chromatography/mass spectrometry (LC/MS) analysis, the limit of detection (LOD) for the major product, triacetylated O6-MedG, was 10 fmol. On reaction of O6-MedG with 14C-acetic anhydride, using a specially designed enclosed system, the predominant product was 14C-di-acetyl O6-MedG. This change in reaction profile was due to a modification of the reaction procedure, introduced as a necessary safety precaution. The LOD for 14C-di-acetyl O6-MedG by AMS was determined as 79 amol, ∼18 000-fold lower than that achievable by liquid scintillation counting (LSC). Although the assay has so far only been carried out with labeled standards, the degree of sensitivity obtained illustrates the potential of this assay for measuring O6-MedG levels in humans. Copyright © 2006 John Wiley & Sons, Ltd.

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