Gupta R C, Earley K, Sharma S
Department of Pharmacology, Baylor College of Medicine, Houston, TX 77030.
Proc Natl Acad Sci U S A. 1988 May;85(10):3513-7. doi: 10.1073/pnas.85.10.3513.
Although animal models have been used successfully to study metabolic activation and binding of carcinogens to DNA, only limited studies have been done in human systems. To circumvent the problems associated with the inaccessibility of human tissues and a lack of sensitive methods to detect DNA damage, we have investigated the capability of human peripheral blood lymphocytes in vitro to metabolize carcinogens to their DNA binding species by a 32P-labeled adduct assay. Freshly isolated lymphocytes were exposed at 37 degrees C for 18 hr to 4-aminobiphenyl, 2-aminofluorene, 2-anthramine, 2-acetylaminophenanthrene, benzidine, 1-nitropyrene, 1,2-benzanthracene, triphenylene, 7,12-dimethylbenz[a]anthracene, or benzo[a]pyrene at 30 microM each, compounds that are shown or suspected to be carcinogenic in experimental animals. Anthracene, pyrene, and perylene were included as noncarcinogenic controls. Our data indicate that all test carcinogens formed readily measurable levels of DNA adducts. Analysis of exposed DNAs by 32P-labeling after digestion and adduct enrichment showed exclusively or predominantly one major adduct for all test carcinogens, except for 2-anthramine, triphenylene, and 7,12-dimethylbenz[a]anthracene, which showed two or three adducts, in the range of 8-1500 amol/micrograms of DNA. No DNA binding was detected for the noncarcinogens. From 12 lymphocyte specimens studied thus far, significant interindividual variations were observed for 2-aminofluorene (62-fold), 7,12-dimethylbenz[a]anthracene (10-fold), benzidine (19-fold) and benzo[a]pyrene (18-fold) in their capacity to bind to the lymphocyte DNA. The lymphocyte system in combination with the 32P-adduct assay may prove to be an ultrasensitive means to determine interindividual variations in the ability to biotransform carcinogens.
尽管动物模型已成功用于研究致癌物的代谢活化及其与DNA的结合，但在人体系统中开展的研究仍很有限。为了规避与人体组织难以获取以及缺乏检测DNA损伤的灵敏方法相关的问题，我们通过32P标记加合物检测法，研究了人外周血淋巴细胞在体外将致癌物代谢为其DNA结合形式的能力。将新鲜分离的淋巴细胞在37℃下暴露18小时，使其分别接触浓度均为30微摩尔的4-氨基联苯、2-氨基芴、2-蒽胺、2-乙酰氨基菲、联苯胺、1-硝基芘、1,2-苯并蒽、三亚苯、7,12-二甲基苯并[a]蒽或苯并[a]芘，这些化合物在实验动物中已被证明或怀疑具有致癌性。蒽、芘和苝作为非致癌对照物。我们的数据表明，所有受试致癌物均形成了易于测量水平的DNA加合物。对消化和加合物富集后的DNA进行32P标记分析显示，除2-蒽胺、三亚苯和7,12-二甲基苯并[a]蒽显示出两到三种加合物（范围为8 - 1500 amol/微克DNA）外，所有受试致癌物仅形成或主要形成一种主要加合物。未检测到非致癌物与DNA的结合。在目前研究的12份淋巴细胞标本中，观察到2-氨基芴（62倍）、7,12-二甲基苯并[a]蒽（10倍）、联苯胺（19倍）和苯并[a]芘（18倍）与淋巴细胞DNA结合能力存在显著的个体间差异。淋巴细胞系统与32P加合物检测法相结合，可能被证明是一种超灵敏的手段，用于确定个体间生物转化致癌物能力的差异。
