ACTIVATION OF CARCINOGENS BY UROTHELIUM IN VITRO

来检验膀胱癌致癌物质被激活的假说 通过与移行上皮相关的酶在细胞内 膀胱的细胞，这些细胞的代谢能力将是 调查过了。人类膀胱癌致癌物的生物激活， 4-氨基二苯基(ABP)、4-硝基联苯(NBP)和实验性膀胱 致癌物N-[4-(5-硝基-2-呋喃)-2-噻唑基]甲酰胺(FANFT) 用正常人和大鼠的尿路上皮细胞进行检测。的性质 尿路上皮细胞激活的中间体(S)将被评估 通过检测某些酶的胞浆和微粒体组分 N-氧化、硝基还原、N-葡萄糖醛酸化、 硫酸盐化、乙酰化、脱乙酰化和N-O转酰化； 鉴定DNA致癌加合物。DNA致癌物的加合物将是 氚处理后培养的人尿路上皮细胞的分离 标记ABP、NBP、4-亚硝基联苯、N-羟基氨基联苯或其 N-葡萄糖醛酸偶联物。生成的加合物的轮廓 培养的细胞将与通过化学作用获得的细胞进行比较。 N-羟氨基联苯及其N-葡萄糖醛酸衍生物与小牛胸腺的作用 在pH为5.0的条件下进行DNA体外培养。的形成和生物反应性 最接近的代谢物将通过尿路上皮介导的方法进行评估。 鼠伤寒沙门氏菌菌株的致突变性试验。长距离飞行 这个项目的目标是了解哪些加合物和酶 在由ABP引起的人类癌症的发生中起决定性作用 及其相关类似物，并找出与代谢有关的因素 对于观察到的对ABP诱导的膀胱的敏感性的差异 老鼠和人类之间的致癌作用。

To test the hypothesis that activation of bladder carcinogens occurs intracellularly by enzymes associated with the transitional epithelial cells of the bladder, the metabolic capabilities of these cells will be investigated. The bioactivation of the human urinary bladder carcinogen, 4-aminobiophenyl(ABP); 4-nitrobiphenyl(NBP); and the experimental bladder carcinogen N-[4-(5-nitro-2-furyl)-2-thiazolyl] formamide (FANFT) will be examined using normal human and rat urothelial cells. The nature of intermediate(s) that are activated by the urothelial cells will be assessed by testing the cytosolic and microsomal fractions for certain enzymatic activities such as N-oxidation, nitroreduction, N-glucuronidation, sulfation, acetylation, deacetylation and N--O transacylation; and by identifying the DNA-carcinogen adducts. The DNA-carcinogen adducts will be isolated from cultured human urothelial cells after treatment with tritium labeled ABP, NBP, 4-nitrosobiphenyl, N-hydroxylaminobiphenyl or its N-glucuronide conjugate. The profiles of the adducts generated from cultured cells will be compared with those obtained by chemical interaction of N-hydroxylaminobiphenyl or its N-glucuronide derivative with calf thymus DNA in vitro at pH 5.0. The formation of, and biological reactivities of the proximate metabolites will be assessed by urothelium-mediated mutagenicity tests in Salmonella typhimurium strains. A long range objective of this project is to understand which of the adducts and enzymes play a determinate role in the initiation of human cancers caused by ABP and its related analogs; and to find out the metabolic factors responsible for the observed differences in susceptibility to ABP-induced bladder carcinogenesis between rats and humans.