FUNCTION OF THE CPH ONCOGENE IN MAMMALIAN CARCINOGENESIS

此延续应用程序的中心目标是确定 新的CPH癌基因和原癌基因的功能及其作用 激活的癌基因在肿瘤发生中的作用。CPH癌基因是 在PI的实验室中从化学引发的肿瘤中分离出来 叙利亚仓鼠胚胎细胞，与人类相关的致癌模型 肿瘤。我们之前的结果证明CPH起作用 与ras协同转化小鼠成纤维细胞。 在本供资期间取得的结果表明，CPH 从酵母到人类细胞都是保守的，在大多数成年人中都有表达 组织，表明它在细胞内起着重要的作用 监管。此外，我们还发现：i)CPH被激活 导致截短基因合成的点突变缺失 蛋白质产物，II)CPH蛋白具有显著的全球同源性 到酵母GDPase，以及iii)当过表达时，CPH使细胞 更能抵抗各种形式的压力。我们假设 活化的CPH癌基因是一种失控的、高活性的核苷 二磷酸酶(NDPase)为细胞提供优越的应激- 生存功能和增殖优势。这一假说将 通过几种方法进行检验：1)结构决定因素分析 (调节序列的获得和/或丢失)CPH转化活性。 2)证明CPH蛋白的NDPase活性，通过 GDPase阴性酵母突变株的互补及纯化， 天然哺乳动物蛋白质的微测序和活性分析。3) 研究CPH转化的机制是否 NDPase活性是必需的，CPH癌蛋白是 错位或与异常细胞底物相互作用。4) 建立CPH在细胞应激反应中的作用 小路。这些研究将扩大我们对 癌基因在致癌过程中的首次展示 NDPase对恶性肿瘤的贡献。这样做的长期目标是 建议将所获得的知识扩展到人类细胞，并将其应用于 目的是研究CPH在人类肿瘤发生中的可能作用.

The central objective of this continuation application is to determine the function of the novel cph oncogene and proto-oncogene, and the role of the activated oncogene in tumorigenesis. The cph oncogene was isolated in the PI's laboratory from chemically-initiated, neoplastic Syrian hamster embryo cells, e carcinogenesis model relevant to human neoplasia. Our previous results demonstrated that cph acts synergistically with ras in the transformation of murine fibroblasts. Results obtained during the present funding period have shown that cph is conserved from yeast to human cells and is expressed in most adult tissues, suggesting that it plays an important role in cellular regulation. In addition we have found that: i) cph is activated by point mutational deletions which result in the synthesis of truncated protein products, ii) the cph proteins have significant global homology to the yeast GDPase, and iii) when overexpressed, cph makes the cells more resistant to various forms of stress. We hypothesize that the activated cph oncogene is a disregulated, hyperactive nucleoside diphosphatase (NDPase) which provides the cells with superior stress- survival functions and proliferative advantage. This hypothesis will be tested by several approaches: 1) Analysis of structural determinants (gain and/or loss of regulatory sequences) of cph transforming activity. 2) Demonstration of the NDPase activity of the cph proteins, by complementation of GDPase-null yeast mutants and by purification, microsequencing and activity assays of native mammalian proteins. 3) Study the mechanism of cph transformation with regard to whether the NDPase activity is required and whether the cph oncoprotein is either mislocalized or interacts with abnormal cellular substrates. 4) Establish the participation of cph in the cellular stress-response pathways. These studies will expand our knowledge on the role of oncogenes in the carcinogenesis process by showing for the first time the contribution of a NDPase to malignancy. The long term goal of this proposal is to extend the knowledge gained to human cells, and to apply it to study the possible role of cph in human neoplasia.