ACTIVATION OF CARCINOGENS BY UROTHELIUM IN VITRO

这个项目的主要目的是阐明生物化学 4-氨基联苯（ABP）诱导膀胱炎的机制 致癌作用 我们假设酶存在于 在膀胱移行上皮细胞中激活ABP 和/或其近似代谢物。 使用人类泌尿上皮细胞 (UEC)和人膀胱癌原ABP作为模型 系统，我们将检查生化步骤和酶 参与ABP及其近似代谢物的活化， 即N-羟基-4-氨基联苯（N-OH-ABP），其N- 葡糖苷酸（N-Glu-OH-ABP），N-羟基-4-乙酰氨基联苯 （N-OH-AABP）及其O-葡糖苷酸（N-OGlu-AABP）。 的 由人UEC激活的近似代谢物将被 通过以下方法测定：1）检测细胞溶质和微粒体组分 人UEC的某些酶活性， 乙酰化，脱乙酰化，转乙酰化，磺化， 葡萄糖醛酸化和过氧化; ii）分离和鉴定 DNA加合物;和iii）测定UEC介导的致突变性。 我们对人UEC的研究结果表明，脱乙酰酶可能 参与N-OH-AABP的活化。 的作用 脱乙酰酶在膀胱癌易感性中的作用 将评估ABP和4-乙酰氨基联苯（AABP）。 为了实现这一目标，定性和定量比较 目的研究去乙酰化酶在UEC中的分布， 难治性（大鼠）与易感性（人和犬）种属将 进行。 亲电分子相互作用的生物学效应 将检查ABP与尿路上皮细胞DNA的代谢产物 通过致突变试验。 为此，我们将首先开发一个 人UEC致突变性系统选择突变体， 次黄嘌呤-鸟嘌呤磷酸核糖转移酶（HGPRT）基因座。 随后，我们将测试不同的 ABP直接在靶尿路上皮上的近似代谢物 细胞 因此，这些研究解决了关键的生化机制， 参与人类膀胱肿瘤的发生。 的 从这些研究中获得的信息将有助于确定 可能与易感性有关的关键代谢因素 芳胺诱导的膀胱癌。

The main objective of this project is to elucidate the biochemical mechanisms of 4-aminobiphenyl (ABP)-induced bladder carcinogenesis in humans. We hypothesize that enzymes present in the transitional epithelial cells of the bladder activate ABP and/or its proximate metabolites. Using human uroepithelial cells (UEC) and the human bladder carcinogen, ABP, as a model system, we will examine the biochemical steps and enzymes involved in the activation of ABP and its proximate metabolites, namely N-hydroxy-4-aminobiphenyl (N-OH-ABP), its N- glucuronide (N-Glu-OH-ABP), N-hydroxy-4-acetylaminobiphenyl (N-OH-AABP) and its O-glucuronide (N-OGlu-AABP). The proximate metabolites that are activated by human UEC will be determined by: 1) testing the cytosolic and microsomal fractions of human UEC for certain enzymatic activities such as acetylation, deacetylation, transacetylation, sulfonation, glucuronidation and peroxidation; ii) isolating and identifying the DNA-adducts; and iii) assaying for UEC-mediating mutagenicity. Our results with human UEC demonstrate that deacetylase may be involved in the activation of N-OH-AABP. The role of deacetylase(s) in susceptibility to bladder carcinogenesis induced by ABP and 4-acetylaminobiphenyl (AABP) will be assessed. Towards this aim, qualitative and quantitative comparative studies on the distribution of deacetylase(s) in the target UEC of refractory (rat) versus susceptible (human and dog) species will be conducted. The biological effects of the interactions of the electrophilic metabolites of ABP with urothelial cellular DNA will be examined by mutagenicity tests. For this purpose, we will first develop a human UEC-mutagenicity system selecting for mutants at the hypoxanthine-guanine phosphoribosyl transferase (HGPRT) locus. Subsequently we will test the mutagenic effects of the different proximate metabolites of ABP directly on the target urothelial cells. These studies thus address the critical biochemical mechanisms involved in the initiation of bladder neoplasia in humans. The information gained from these studies will be useful in identifying the key metabolic factors that might be involved in susceptibility to arylamine-induced bladder carcinogenesis.