ToxSci Advance Access originally published online on November 6, 2006
Toxicological Sciences 2007 95(2):383-390; doi:10.1093/toxsci/kfl155
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Cytogenetic Damage Induced by Acrylamide and Glycidamide in Mammalian Cells: Correlation with Specific Glycidamide-DNA Adducts
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* Department of Genetics, Faculty of Medical Sciences, New University of Lisbon, 1349-008 Lisboa, Portugal
Faculty of Pharmacy, University of Lisbon, Avenida das Forças Armadas, 1649-019 Lisboa, Portugal
Section of Molecular Carcinogenesis, The Institute of Cancer Research, Sutton, Surrey SM2 5NG, United Kingdom
Centro de Química Estrutural, Instituto Superior Técnico, 1049-001 Lisboa, Portugal
¶ Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, Arkansas 72079
2 To whom correspondence should be addressed at Department of Genetics, Faculty of Medical Sciences, New University of Lisbon, Rua da Junqueira 96, 1349-008 Lisboa, Portugal. Fax: +351 213622018. E-mail: jgaspar.gene{at}fcm.unl.pt.
Received August 11, 2006; accepted October 25, 2006
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Abstract |
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Acrylamide (AA) is a suspected human carcinogen generated in carbohydrate-rich foodstuffs upon heating. Glycidamide (GA), formed via epoxidation, presumably mediated by cytochrome P450 2E1, is thought to be the active metabolite playing a central role in AA genotoxicity. In this work we investigated DNA damage induced by AA and GA in mammalian cells, using V79 Chinese hamster cells. For this purpose, we evaluated two cytogenetic end points, chromosomal aberrations (CAs) and sister chromatid exchanges (SCEs), as well as the levels of specific GA-DNA adducts, namely, N7-(2-carbamoyl-2-hydroxyethyl)guanine (N7-GA-Gua) and N3-(2-carbamoyl-2-hydroxyethyl)adenine (N3-GA-Ade) using high-performance liquid chromatography coupled with tandem mass spectrometry. GA was more cytotoxic and clastogenic than AA. Both AA and GA induced CAs (breaks and gaps) and decreased the mitotic index. GA induced SCEs in a dose-responsive manner; with AA, SCEs were increased at only the highest dose tested (2mM). A linear dose-response relationship was observed between the GA concentration and the levels of N7-GA-Gua. This adduct was detected for concentrations as low as 1µM GA. N3-GA-Ade was also detected, but only at very high GA concentrations (
250µM). There was a very strong correlation between the levels of N7-GA-Gua in the GA- and AA-treated cells and the extent of SCE induction. Such correlation was not apparent for CAs. These data suggest that the induction of SCEs by AA is associated with the metabolism of AA to GA and subsequent formation of depurinating DNA adducts; however, other mechanisms must be involved in the induction of CAs.
Key Words: acrylamide; glycidamide; DNA adducts; chromosomal aberrations; sister chromatid exchanges.