Activation of aflatoxin B1 by expression of human CYP1A2 polymorphisms in Saccharomyces cerevisiae.
Human susceptibility to environmental carcinogens is highly variable and depends on multiple genetic factors, including polymorphisms in cytochrome P450 genes. Although epidemiological studies have identified individual polymorphisms in cytochrome P450 genes that may alter cancer risk, there is often conflicting data about whether such polymorphisms alter the genotoxicity of environmental carcinogens. This is particularly true of the CYP1A2 polymorphisms that confer differential activation of multiple human carcinogens. To determine whether a single cytochrome P450 polymorphism confers higher levels of carcinogen-associated genotoxicity, we chose an organism that lack enzymes to metabolically activate aflatoxins and expressed individual human P450 genes in budding yeast. We measured the frequencies of recombination, Rad51 foci formation, 7-methoxyresorufin O-demethylase activities, and the concentrations of carcinogen-associated DNA adducts in DNA repair proficient yeast expressing P450 polymorphisms after exposure to aflatoxin B1 (AFB1).We measured growth of rad4 rad51 cells expressing CYP1A2 polymorphisms while exposed to AFB1. We observed that there was significantly less AFB1-associated genotoxicity in yeast expressing CYP1A2 I386F, while yeast expressing CYP1A2 C406Y exhibited intermediate levels of genotoxicity compared to yeast expressing CYP1A2 D348N or wild type. We conclude that differences in carcinogen genotoxicity can be observed in yeast expressing different CYP1A2 alleles. This is the first report that carcinogen-associated P450 polymorphisms can be studied in yeast.
Ordway Research Institute, Center for Medical Sciences, 150 New Scotland Avenue, Albany, NY 12209, USA; Department of Biomedical Sciences, School of Public Health, Center for Medical Sciences, 150 New Scotland Avenue, Albany NY, USA. Electronic address: mfasullo@albany.edu.
Michael
M
Fasullo
Ordway Research Institute, Center for Medical Sciences, 150 New Scotland Avenue, Albany, NY 12209, USA.
Autumn
A
Smith
Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.
Patricia
P
Egner
Ordway Research Institute, Center for Medical Sciences, 150 New Scotland Avenue, Albany, NY 12209, USA.
Cinzia
C
Cera
D016604:Aflatoxin B1 / Q000378:metabolism / Q000633:toxicity*; D019943:Amino Acid Substitution; D002273:Carcinogens / Q000378:metabolism / Q000633:toxicity*; D019388:Cytochrome P-450 CYP1A2 / Q000235:genetics* / Q000378:metabolism*; D018736:DNA Adducts / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic; D015966:Gene Expression Regulation, Fungal; D006801:Humans; D030781:Organisms, Genetically Modified; D011110:Polymorphism, Genetic; D051135:Rad51 Recombinase / Q000235:genetics; D011995:Recombination, Genetic / Q000187:drug effects; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics
D002273:Carcinogens; D018736:DNA Adducts; D004268:DNA-Binding Proteins; C493797:Rad4 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D016604:Aflatoxin B1; D019388:Cytochrome P-450 CYP1A2; C495151:RAD51 protein, S cerevisiae; D051135:Rad51 Recombinase
Aflatoxin B(1); Budding yeast; Cytochrome P450