ACTIVATION OF CARCINOGENS BY UROTHELIUM IN VITRO

为了验证膀胱致癌物激活的假设， 与移行上皮细胞相关的酶 膀胱的细胞，这些细胞的代谢能力将是 研究了 人膀胱癌致癌物的生物活化， 4-氨基联苯（ABP）; 4-硝基联苯（NBP）;和实验膀胱 致癌物N-[4-（5-硝基-2-呋喃基）-2-噻唑基]甲酰胺（FANFT）将被 使用正常人和大鼠尿路上皮细胞进行检测。 的性质 将评估由尿路上皮细胞激活的中间体 通过检测细胞质和微粒体组分中的某些酶， 活性如N-氧化、硝基还原、N-葡萄糖醛酸化， 硫酸化、乙酰化、脱乙酰化和N-O转酰化;和 识别DNA致癌物加合物。 DNA-致癌物加合物将 分离自氚处理后培养的人尿路上皮细胞 标记的ABP、NBP、4-亚硝基联苯、N-羟基氨基联苯或其 N-葡糖苷酸结合物。 生成的加合物的概况 将培养的细胞与通过化学相互作用获得的细胞进行比较 N-羟基氨基联苯或其N-葡糖苷酸衍生物与小牛胸腺的反应 DNA在体外pH 5.0。 的形成和生物反应性 将通过尿路上皮介导的 鼠伤寒沙门氏菌菌株的致突变性试验。 远程 这个项目的目的是了解加合物和酶中 在ABP引起的人类癌症的起始中起决定性作用 及其相关的类似物;并找出代谢因素负责 对于观察到的对ABP诱导的膀胱炎易感性的差异， 大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.