DNA ADDUCTS OF AROMATIC AMINES--ANALYSIS BY MS AND P-32

接触多种致癌物质会导致DNA加合物的形成。细胞中DNA加合物含量的测量为暴露和损伤提供了直接证据。对这些所谓的分子标记的分析正在成为评估人类健康风险的一种被接受的工具。我们的长期目标是研究靶组织中DNA加合物的存在与癌变之间的关系。我们正在研究芳香胺的DNA加合物，芳香胺是香烟烟雾和含蛋白质食品中发现的一类化合物。流行病学研究已证实某些芳香胺，如4-氨基联苯(ABP)、2-萘胺和2-氨基-3-甲基咪唑[4，5-f]喹啉(IQ)对人和动物均有致癌作用。这些化合物可以转化为含有氮离子和氮离子官能团的亲电中间体。已知这些物种主要攻击鸟嘌呤残基的C8位。胰腺癌、肺癌或结肠癌组织中含有一种或多种这种化合物的DNA加合物，以及能够激活它们的酶。改进的DNA加合物的检测和表征方法对于我们确定其与癌症的直接关系的目标是重要的。毛细管分离方法(高效液相色谱和毛细管电泳联用)与电喷雾电离/串联质谱仪相结合，将用于分析吸烟者的肺和胰腺组织，以评估ABP在人类癌症发生中的作用。暴露在芳香胺中的动物模型的组织将被用作开发该方法的替代物。将与目前最广泛使用的加合物分析方法--32P-后标记进行比较。然而，这种方法不提供加合物的直接结构信息或序列偏好。为了解决这些重要问题，将使用CE-MS来表征寡核苷酸加合物，以确定致癌物的序列识别模式。预计这项计划将导致建立一种严格的质谱学方法来研究DNA加合物并使用生物标记物进行风险评估。

Exposure to a wide variety of carcinogens leads to the formation of DNA adducts. Measurement of DNA adduct content in cells provides direct evidence for exposure and damage. Analysis of these so-called molecular markers are becoming an accepted tool for assessing human health risk. Our long term objective is the correlation between the presence of DNA adducts and carcinogenesis in target tissues. We are investigating DNA adducts of aromatic amines, a class of compounds found in cigarette smoke and protein-containing foods. Epidemiological studies have established the carcinogenicity of certain aromatic amines such as 4- aminobiphenyl (ABP), 2-naphthylamine and 2-amino-3-methylimidazo[4,5- f]quinoline (IQ) in both humans and animals. These compounds can be converted to electrophilic intermediates containing nitrene and nitrenium ion functional groups. These species are known to attack predominantly the C8 position of guanine residues. Pancreatic, lung or colon cancerous tissues contain DNA adducts of one or more of these compounds as well as the enzymes capable of activating them. Improved methods for detection and characterization of DNA adducts are important toward our goal of establishing their direct relationship to cancer. Capillary separation methods (HPLC and capillary electrophoresis) coupled to electrospray ionization/tandem mass spectrometry will be used to analyze human lung and pancreatic tissues from smokers in order to assess the role of ABP in human carcinogenesis. Tissues from animal models exposed to aromatic amines will be used as surrogates in developing the methodology. Comparisons will be made to 32P- post- labeling, currently the most widely used method of adduct analyses. However, this methodology does not provide direct structural information or sequence preferences of the adduct. To address these important issues, CE-MS will be used to characterize oligonucleotide adducts in order to determine sequence recognition patterns of carcinogens. It is expected that this program will lead to the establishment of a rigorous mass spectrometric methodology for the study of DNA adducts and the use of biomarkers for risk assessment.