MECHANISMS OF CELL REPLICATION IN ASBESTOS CANCERS

本项目将重点研究青石棉的分子机制。 温石棉诱导啮齿动物胸膜增殖 间皮(RPM)和气管、支气管上皮(HTE)细胞 间皮瘤和肺癌的祖细胞。自.以来 细胞增殖的增加是因果关系和/或促成的 许多癌症，我们假设石棉纤维提供了一种持久的 有丝分裂刺激是肿瘤发展所必需的，这是由 石棉对c-fos和c-jun原癌基因的持续诱导作用。至 确定青石棉和温石棉是否通过相似的方式诱导增殖 或在不同细胞类型中的独特过程，我们将研究其机制 抑制剂对c-fos和c-jun基因表达的影响 蛋白激酶C(PKC)和ADP-核糖转移酶。Active的清道夫 氧物种(AOS)和铁络合纤维将被用来测试 石棉相关的c-fos和c-jun的诱导可能是 由AOS调停。此外，使用非石棉进行的对比实验 类似的纤维[耐火陶瓷(RCF)和玻璃(MMVF-10)] 尺寸为石棉，长(&gt；10微米)与短(&lt；2微米) 温石棉纤维和类似化学物质的颗粒(丽贝石、玻璃) 石棉在一定浓度范围内的组成将决定 C-fos和c-jun诱导所固有的纤维特性。是否 这些原癌基因的高表达与细胞 石棉扩散的评估将使用瞬变 评价青石棉和温石棉效果的转染法 纤维对hte细胞中AP-1依赖报告基因表达的影响 C-fos和c-jun蛋白在细胞培养中的免疫定位 暴露在石棉下。在后面的实验中，我们将使用 免疫细胞化学检测c-fos和c-jun蛋白是否 仅在增生性间皮细胞和气管中表达 由增殖细胞表达鉴定的上皮细胞 核抗原或5‘-溴脱氧尿苷的掺入 (BrdU)转化为DNA。暴露于空气中的细胞对比实验 纤维的增殖和细胞毒性浓度在体外和 吸入空气后c-fos和c-jun蛋白的原位定位 老鼠的纤维将使我们能够将这些基因产物的表达联系起来 与细胞增殖和/或细胞毒性有关。机制方面的知识 石棉对石棉靶细胞c-fos和c-jun的诱导作用 诱发癌症将为预防和治疗开辟新的途径 治疗疾病的方法。该项目涉及博士之间的合作。 莫斯曼是一位在石棉和AOS方面有专长的细胞生物学家，海因茨博士说， 一位在细胞复制方面有专长的分子生物学家和莱斯利博士， 一位在免疫细胞化学方面有专长的肺部病理学家。

This project will focus on the molecular mechanisms by which crocidolite and chrysotile asbestos induce proliferation of rodent pleural mesothelial (RPM) and tracheobronchial epithelial (HTE) cells, the progenitor cells of mesotheliomas and bronchogenic carcinomas. Since increased cell proliferation is causally related and/or contributory to many cancers, we hypothesize that asbestos fibers provide a persistent mitogenic stimulus necessary for tumor development as is suggested by the persistent induction of c-fos and c-jun protooncogenes by asbestos. To determine if crocidolite and chrysotile induce proliferation by similar or unique processes in various cell types, we will examine the mechanisms of activation of c-fos and c-jun gene expression using inhibitors of protein kinase C (PKC) and ADP-ribose transferase. Scavengers of active oxygen species (AOS) and iron-chelated fibers will be used to test the hypothesis that asbestos-associated induction of c-fos and c-jun may be mediated by AOS. Moreover, comparative experiments using nonasbestos fibers [refractory ceramic (RCF) and glass (MMVF-10)] of similar dimension to asbestos, sized long (>10 microm) vs. short (<2 micro) chrysotile fibers, and particles (riebeckite, glass) of similar chemical composition to asbestos at a range of concentrations will determine the properties of fibers intrinsic to induction of c-fos and c-jun. Whether increased expression of these protooncogenes is causally related to cell proliferation by asbestos will be assessed using both transient transfection assays to assess the effects of crocidolite and chrysotile fibers on the expression of an AP-1 dependent reporter gene in HTE cells and immunolocalization of c-fos and c-jun proteins in cell cultures exposed to asbestos. In the latter experiments, we will use immunocytochemistry to determine if c-fos and c-jun proteins are expressed exclusively in proliferating mesothelial and tracheal epithelial cells as identified by the expression of proliferating cell nuclear antigen (PCNA) or the incorporation of 5'-bromo-deoxyuridine (BrdU) into DNA. Comparative experiments using cells after exposure to both proliferative and cytotoxic concentrations of fibers in vitro and in situ localization of c-fos and c-jun proteins after inhalation of fibers by rats will allow us to link expression of these gene products with cell proliferation and/or cytotoxicity. Knowledge of the mechanisms of induction of c-fos and c-jun by asbestos in target cells of asbesto- induced cancers will open up avenues for preventive and therapeutic approaches to disease. This project involves collaborations between Dr. Mossman, a cell biologist with expertise in asbestos and AOS, Dr. Heintz, a molecular biologist with expertise in cell replication, and Dr. Leslie, a lung pathologist with expertise in immunocytochemistry.