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Aflatoxin-guanine DNA Adducts and Oxidatively-induced DNA Damage in Aflatoxin-treated Mice in vivo as Measured by Liquid Chromatography-Tandem Mass Spectrometry with Isotope-dilution

Published

Author(s)

Erdem Coskun, Pawel Jaruga, Vladimir Vartanian, Onur Erdem, Patricia Egner, John D. Groopman, R. S. Lloyd, Miral M. Dizdar

Abstract

Dietary exposure to aflatoxin (AFB1) is a significant reason for the incidence of hepatocellular carcinomas globally. AFB1-exposure leads to the formation of AFB1-N7-guanine (AFB1-N7-Gua) and two diastereomers of 8,9-dihydro-8-(2,6-diamino-4-oxo-3,4-dihydropyrimid-5-yl-formamido)-9- hydroxyaflatoxin B1 (AFB1-N7-FapyGua) in DNA. These adducts lead to G → T transversion mutations with the latter being more mutagenic than the former. Positive identification and accurate quantification of these three adducts as biomarkers in DNA and urine will help identify dietary exposure to AFB1 as a risk factor in the development of hepatocellular carcinoma worldwide. We report on an improved methodology for the measurement of AFB1-N7-Gua and the two diastereomers of AFB1-N7-FapyGua using liquid chromatography-tandem mass spectrometry with isotope-dilution. We identified and quantified the levels of these compounds in liver DNA of six control mice and six AFB1-treated mice. Levels varying from 1.5 to 45 lesions/106 DNA bases in AFB1-treated mice were detected depending on the compound and animal. Control mice had no detectable background levels of these compounds in their liver DNA. We also tested whether the AFB1-treatment causes oxidatively- induced DNA base damage using gas chromatography-tandem mass spectrometry with isotope-dilution. Although background levels of several pyrimidine- and purine-derived lesions were detected, no increases in these levels were found upon AFB1-treatment of mice. On the other hand, significantly increased levels of (5'R)- and (5'S)-8,5'-cyclo-2'-deoxyadenosines were observed in liver DNA of AFB1-treated mice. The concept presented in this work is expected to achieve the accurate measurement of three AFB1-DNA adducts and oxidatively-induced DNA lesions as biomarkers of AFB1- exposure for several aspects of prevention of aflatoxin-related hepatocellular carcinomas and for determining the effects of genetic deficiencies in human population.
Citation
Chemical Research in Toxicology
Volume
32
Issue
1

Keywords

Aflatoxin-guanine DNA Adducts, Oxidatively-induced DNA Damage, biomarkers of AFB1-exposure, LC- MS/MS, GC-MS/MS

Citation

Coskun, E. , Jaruga, P. , Vartanian, V. , Erdem, O. , Egner, P. , Groopman, J. , Lloyd, R. and Dizdar, M. (2018), Aflatoxin-guanine DNA Adducts and Oxidatively-induced DNA Damage in Aflatoxin-treated Mice in vivo as Measured by Liquid Chromatography-Tandem Mass Spectrometry with Isotope-dilution, Chemical Research in Toxicology, [online], https://doi.org/10.1021/acs.chemrestox.8b00202 (Accessed April 16, 2024)
Created December 10, 2018, Updated October 12, 2021