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Détection des adduits à l'ADN comme biomarqueurs d'exposition aux substances génotoxiques de l'environnement

Detection of environmental carcinogens-DNA

A. Pfohl-Leszkowicz, G. Guillemaut, J.F. Masfaraud, B. Rether et J.M. Haguenoer

p. 51-57

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Résumé

De nombreux xénobiotiques ou leurs métabolites se lient de manière covalente à l'ADN et provoquent des modifications entraînant une altération de l'information génétique à l'origine de cancers. La méthode du postmarquage de l'ADN au phosphore 32 constitue un outil très performant permettant la détection et la quantification de ces adduits à l'ADN comme biomarqueurs d'exposition à diverse s substances chimiques génotoxiques de l'environnement. Nous avons montré (i) qu'il était possible d'avoir une idée de l'état de pollution d'une rivière en recherchant les adduits sur l'ADN de foie de poissons ; (ii) que le dépérissement de certaines plantes était corrélé à la présence d'adduits à l'ADN provenant de la pollution par les gaz d'échappement et par des pesticides et (iii) que dans le cancer, des adduits pouvaient être détectés dans les organes cibles. Dans tous ces exemples, nous avons établi une corrélat ion avec le métabolisme de diverses substances.

Abstract

In has been estimated that majority of human cancer is due to environmental factors including pollutants in air, soil, water and food. work places exposure and personal habits such as smoking. After penetration in organism, xenobiotics could be directly excreted or are biotrenstormed by oxidation or reduction in more hydrophilic compounds which could be conjugate and then eliminated in urine. But in some case, the biotransformation leads to electrophilic compounds which interact with macromolecules such as DNA, forming addition products named adduct.
The 32P-postlabelling method, inspired by recent developments in the methodology for sequencing nucleic acids, is an extremely sensitive method for assessing and quantifying DNA adducts and is applicable to structurally diverse classes of chemicals.
In the assessment of genotoxic risks in environment, the measurement of carcinogen-DNA adducts, in aquatic system or in plants may have considerable implications In the first study, we have analysed hepatic DNA from fish living in the River Rhone downstream and upstream from a polychlorinated biphenyl Incineration plant. Our results suggest that fish are exposed to qenotoxic chemicals (which bind on DNA directly or after metabolic activation), with a specific contamination of the downstream site.
In another study, leave DNA from healthy and declining hop were analysed. As high level of heptachlor have be found in the soil where hop were declining, we search for DNA adducts. We can observed faint adduct in healthy hop and high quantity of specific adducts in declining hop. The total adduct level is 3 time higher in declining hop. A comparison between DNA adducts from several vegetal cells cultured in presence of heptachlor and DNA adduct in declining hop. Confirmed the implication of heptachlor. In these examples, our data indicate the usefullness of the 32P-postlabelling method to assess the contamination of the environment by genotoxic pollutants.
Epidemiological data suggested that increasing exposure to airborne PAH contributes to increase risk cancer in this population. Airborne levels of B(a)P were used to estimate exposure. Exposure-dependent adducts were detected in white blood cells in coke oven workers. The adduct levels is function of the level of pollutant. In the last exemple, we have analysed lung tissue from patient with cancer. We observed many adducts in peritumoral tissue, white few adducts could be detected in tumoral tissues.
In conclusion. this method is very useful to determine the genotoxicity of a substance. It give a quantitative approximation of distribution. bioactivation, detoxification and persistence of ultimate genotoxic metabolites in target tissues. The detection of covalent adducts has become increasingly important in the assessment of human exposure to carcinogens.
A limitation of the method is its capacity to furnish information as to the nature of adducts. Characterization of adducts has thus far depended upon chromatographic resemblance to reference adducts. The quantity of adducts conveniently obtainable from typical adduct maps is several orders of magnitude lower than the hundreds of nanograms of pure material required for even the highly sensitive mass spectroscopie techniques.

Pour citer ce document

Référence papier : A. Pfohl-Leszkowicz, G. Guillemaut, J.F. Masfaraud, B. Rether et J.M. Haguenoer « Détection des adduits à l'ADN comme biomarqueurs d'exposition aux substances génotoxiques de l'environnement », Pollution atmosphérique, N°147, 1995, p. 51-57.

Référence électronique : A. Pfohl-Leszkowicz, G. Guillemaut, J.F. Masfaraud, B. Rether et J.M. Haguenoer « Détection des adduits à l'ADN comme biomarqueurs d'exposition aux substances génotoxiques de l'environnement », Pollution atmosphérique [En ligne], N°147, mis à jour le : 07/04/2014, URL : http://lodel.irevues.inist.fr/pollution-atmospherique/index.php?id=4019, https://doi.org/10.4267/pollution-atmospherique.4019

Auteur(s)

A. Pfohl-Leszkowicz

Ecole Nationale Supérieure Agronomique (ENSAT), Laboratoire de Toxicologie et Sécurité Alimentaire, 145, avenue de Muret, 31076 Toulouse

G. Guillemaut

IUT, rue de l'Argonne, 67000 Strasbourg

J.F. Masfaraud

CSE, 57040 Metz

B. Rether

IUT, rue de l'Argonne, 67000 Strasbourg

J.M. Haguenoer

Institut Médecine du Travail, 59045 Lille