ACTIVATION OF CARCINOGENS BY UROTHELIUM IN VITRO

这个项目的主要目标是阐明生物化学。 4-氨基联苯(ABP)诱发膀胱的作用机制 人类的致癌作用。我们假设酶存在于 在膀胱移行上皮细胞中激活ABP 和/或其近邻代谢物。使用人的尿路上皮细胞 (UEC)和人类膀胱癌致癌物ABP作为模型 系统中，我们将检查生化步骤和酶 参与ABP及其近邻代谢物的活化， 即N-羟基-4-氨基联苯(N-OH-ABP)，其N-羟基-4-氨基联苯 葡萄糖醛酸苷(N-Glu-OH-ABP)，N-羟基-4-乙酰氨基联苯 (N-OH-AABP)及其O-葡萄糖醛酸苷(N-Oglu-AABP)。这个 被人UEC激活的近似代谢物将是 测定方法：1)检测细胞质和微粒体组分 人类UEC对某些酶活性的影响，如 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；以及iii)检测UEC介导的致突变性。 我们对人类UEC的研究结果表明，脱乙酰酶可能 参与N-OH-AABP的激活。的作用 脱乙酰酶(S)与膀胱癌易感性的关系 通过ABP和4-乙酰氨基联苯(AABP)进行评估。 朝着这一目标，定性和定量进行比较 脱乙酰酶(S)在大鼠肾小管上皮细胞中的分布 难治(老鼠)与易感(人和狗)的物种将是 指挥。 亲电性物质相互作用的生物效应 ABP与尿路上皮细胞DNA的代谢产物将被检测 通过致突变性测试。为此，我们将首先开发一种 人UEC-诱变系统对突变体的筛选 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诱变效果 ABP的近邻代谢物直接作用于靶尿路上皮 细胞。 因此，这些研究解决了关键的生化机制 与人类膀胱瘤的发生有关。这个 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 对芳胺诱发膀胱癌的影响。

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.