Genotoxicity of aflatoxin B1: evidence for a recombination-mediated mechanism in Saccharomyces cerevisiae

Sengstag, C. and Weibel, B. and Fasullo, M.. (1996) Genotoxicity of aflatoxin B1: evidence for a recombination-mediated mechanism in Saccharomyces cerevisiae. Cancer research, 56 (23). pp. 5457-5465.

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The potent liver carcinogen aflatoxin B1 (AFB1) is metabolized by cytochrome P450 to the mutagenic epoxide. We have observed that activated AFB1 also strongly induced mitotic recombination in the yeast Saccharomyces cerevisiae. To compare the recombinogenicity of AFB1 to its mutagenicity, three metabolically competent S. cerevisiae strains have been constructed. The frequencies of induced recombinants resulting from gene conversion or chromosomal translocations were determined by different prototrophic selections using two strains, whereas the inducibility of forward mutations was determined by the frequency of drug resistance in the third strain. Human cytochrome P4501A1- (CYP1A) and NADPH-cytochrome P450-oxidoreductase cDNAs were expressed in the strains to ensure intracellular metabolism to the epoxide. Exposure of the strains to AFB1 resulted in a 139- and 24-fold increase in the translocation and gene conversion frequencies, respectively, whereas the mutation frequency was increased only 3-fold. In contrast, benzo[a]pyrene-7,8-dihydrodiol and ethyl methanesulfonate induced mutation and mitotic recombination to similar degrees. We conclude that AFB1 exerted a strong recombinogenic, but only a weak mutagenic, effect. The recombinogenicity of AFB1 in yeast may indicate a mechanism for the high proportion of loss of heterozygosity that has been detected in AFB1-related human liver cancers.
Faculties and Departments:11 Rektorat und Verwaltung > Vizerektorat Forschung
UniBasel Contributors:Sengstag, Christian
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:American Association for Cancer Research
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:10 Nov 2021 16:28
Deposited On:10 Nov 2021 16:28

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