RAINBOW TROUT--A MODEL FOR ENVIRONMENTAL CARCINOGENESIS

这项建议调查了虹鲑鱼的遗传毒性机制。 作为一个中心主题，主要强调遗传学、分子 致癌和促癌的遗传学和生物化学。许多 在环境健康中使用这种水生模型的属性是合理的 研究。鲑鱼减少了癌症研究对哺乳动物的依赖， 提供比较的机制信息，表现出高度的敏感性 (纳克肿瘤反应)，具有如此低的成本，成千上万的 动物对每个肿瘤的研究是合理的，有零和接近于零 背景关联，并且很容易被操纵来产生克隆或 多倍体。强调机制将扩大我们的比较基础 将代孕者的癌症研究外推到人类身上，同时也 不断加深对野生鱼类肿瘤发展的了解。这个 这个主题中的四个互动项目是：1.调查 鲑鱼肿瘤发生发展的分子基础， 包括：确定发病率的机制、特定地点 Ki-ras p21等位基因的产生和选择性繁殖 致癌物剂量、增殖再生、DNA加合、 和修复能力对Ki-ras活化发生率的影响，降至10-3 肿瘤风险(ED0.1%肿瘤研究)；三倍体作为一种 涉及显性P53点的肿瘤发生的选择性环境 突变。2.研究肿瘤变异的遗传控制 鲑鱼近交、克隆和三倍体群体的反应。利用 用倍体操作评估鲑鱼中肿瘤抑制基因的参与 癌症的发生，并建立了使用RFLP标记和已知 用抑制基因探针研究二倍体和二倍体的缺失 三倍体同基因鲑鱼种群。启动开发 虹鲑鱼DNA标记的遗传图谱。3.建立 鲑鱼早期生活阶段对前致癌物的代谢能力 生物活化和烷基化修复。克隆、测序并建立 三个鲑鱼细胞色素P450新基因的表达。建立 这些基因和另外两条鲑鱼的时间和组织依赖性表达 P450，它们对选定的环境试剂的诱导反应，以及 它们对选定的致癌物进行生物激活的潜力。建立 06-的水平、发育表达和组织分布 烷基转移酶。4.为临床应用，建立机制 通过它天然生成的化合物吲哚-3-甲醇，一种 目前提出的用于人类干预的推定的“抗癌物质” 试验，也具有肿瘤促进剂的作用。调查是否 在鲑鱼和小鼠体内的促进机制是通过ah受体介导的 激励性。严格量化其剂量反应促进作用 以及潜在的促进门槛剂量的存在，以便 评估促销风险与化学预防益处。

This proposal investigates mechanisms of genotoxicity in rainbow trout as a central theme, with a primary emphasis on the genetics, molecular genetics, and biochemistry of carcinogenesis and tumor promotion. Many attributes justify use of this aquatic model in environmental health research. Trout reduce dependence on mammals for cancer research, provide comparative mechanism information, show high sensitivity (nanogram tumor response), have such low cost that many thousands of animals per tumor study are reasonable, have zero and near-zero background incidence, and are readily manipulated to produce clones or polyploids. An emphasis on mechanisms will broaden our comparative base for extrapolating cancer studies from surrogates to humans, while also increasing understanding of tumor development in feral fish species. The four interactive projects within this theme are: 1. Investigate the molecular basis for tumor initiation and development in trout, including: mechanisms that determine the incidence, site-specific generation and selective propagation of Ki-ras p21 allelomorphs; the influence of carcinogen dose, proliferative regeneration, DNA adduction, and repair capacity on the incidence of Ki-ras activation, down to 10-3 tumor risk (ED0.1% tumor study); and the influence of triploid as a selective environment for oncogenesis involving dominant p53 point mutations. 2. Examine the genetic control of variation in tumor response in outbred, clonal, and triploid populations of trout. Utilize ploidy manipulation to assess tumor suppressor gene involvement in trout carcinogenesis, and establish the use of RFLP markers and known suppressor gene probes to investigate deletional events in diploid and triploid populations of isogenic trout. Initiate development of a genetic map of DNA markers for rainbow trout. 3. Establish the metabolic capacity of early trout life stages for procarcinogen bioactivation and alkylation repair. Clone, sequence, and establish the expression of three new trout cytochrome P450 genes. Establish the time- and tissue-dependent expression of these and two additional trout P450s, their inductive response to selected environmental agents, and their potential to bioactivate selected procarcinogens. Establish the levels, developmental expression, and tissue distribution of 06- alkyltransferase. 4. For clinical application, establish the mechanisms through which the naturally occurring compound indole-3-carbinol, a putative "anticarcinogen" currently proposed for human intervention trials, also behaves as a tumor promoter. Investigate if the promotional mechanism is mediated in trout and mice through Ah receptor agonism. Rigorously quantify its dose-responsive promotional potency and the potential presence of a threshold dose for promotion, in order to assess promotional risk vs. chemopreventive benefit.