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Protection by dietary compounds against mutation in a transgenic rodent
1Centre for Environmental Health, University of Victoria, Victoria, British Columbia, Canada. jdboer@uvic.ca
Abstract:
One of the most relevant biomarkers of genotoxicity and, potentially, carcinogenesis is the occurrence of mutations. Data indicate that carcinogens are highly specific with regard to their target tissue in inducing both tumors and mutations. This specificity may reflect the dependence on tissue-specific metabolic activation, the organ-specific environment or both. Ideally, therefore, mutation should be determined in a real animal rather than in a cell culture system. The lacI transgenic rodent model provides such a system. We have used this model to investigate tissue, species and sex specificity of mutation induced by selected dietary carcinogens and to examine how some compounds may alter the induction of mutation. We have studied mutation using several chemicals, including the dietary heterocyclic amine 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), the environmentally important aromatic hydrocarbon benzo[a]pyrene and the food contaminant aflatoxin B1. We have shown that the mutagenic potency of these chemicals can be modulated by other dietary compounds, including green tea and conjugated linoleic acid, and the dioxin 2,3,7,8-tetrachlorodibenzo[b,e][1,4]dioxin (TCDD). These results demonstrate that the lacI transgenic rodent is a useful model for the study of chemoprevention in vivo.
Insights
Genotoxicity biomarkers like mutations are tissue-specific. The lacI transgenic rodent model effectively studies mutation induction by dietary carcinogens and modulation by other compounds.
Area of Science:
- Toxicology
- Genetics
- Carcinogenesis
Background:
- Mutations are key biomarkers for genotoxicity and potential carcinogenesis.
- Carcinogen-induced mutations and tumors exhibit tissue specificity, possibly due to metabolic activation or organ-specific environments.
- In vivo mutation assessment is crucial, making animal models preferable to cell cultures.
Purpose of the Study:
- To investigate the tissue, species, and sex specificity of mutations induced by dietary carcinogens.
- To examine how various compounds modulate carcinogen-induced mutation induction.
- To evaluate the utility of the lacI transgenic rodent model for studying chemoprevention in vivo.
Main Methods:
- Utilized the lacI transgenic rodent model for in vivo mutation analysis.
- Studied mutations induced by specific dietary carcinogens: 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), benzo[a]pyrene, and aflatoxin B1.
- Assessed the modulatory effects of dietary compounds like green tea, conjugated linoleic acid, and 2,3,7,8-tetrachlorodibenzo[b,e][1,4]dioxin (TCDD) on mutagenic potency.
Main Results:
- Demonstrated tissue, species, and sex-specific mutation induction by PhIP, benzo[a]pyrene, and aflatoxin B1.
- Showed that the mutagenic potency of these carcinogens can be significantly modulated by co-administered dietary compounds and TCDD.
- Confirmed the lacI transgenic rodent model's effectiveness in studying in vivo chemoprevention.
Conclusions:
- The lacI transgenic rodent model is a valuable tool for studying the complexities of carcinogen-induced mutations in vivo.
- Dietary factors and environmental contaminants can significantly alter the mutagenic effects of carcinogens.
- Findings support the application of this model for evaluating chemopreventive strategies against genotoxicity.