ACTION OF THE ONCOGENE INT-1 IN MAMMARY TUMORS

int-1基因被插入小鼠乳腺癌细胞激活， 肿瘤病毒（MMTV）前病毒DNA在MMTV诱导的肿瘤中的作用， 其蛋白质产物与肿瘤发生密切相关。 的 基因在某些乳腺上皮细胞中具有转化活性 但在成纤维细胞中没有。 int-1也与 妊娠中期中枢神经系统的发育 小鼠胚胎 最近的数据表明，int-1蛋白质产品 可能进入分泌途径，该基因可能通过 一种可扩散因子的分泌。 本研究的目的是 研究int-1介导的转化机制， 该基因在肿瘤发生途径中的作用。 具体来说，我们将测试int-1编码a的假设。 新的生长因子 多克隆抗体将针对 int-1融合蛋白在E.大肠杆菌，用于检测 细胞培养基中分泌形式的int-1蛋白。 我们 还应通过以下方式寻找int-1依赖性分泌因子的证据： 其预测的促有丝分裂活性对适当的乳腺癌的方法 细胞 为了开始int-1蛋白的功能分析， 特定的缺失和定点突变将在 int-1;然后将在int-1中测试其生物活性 响应细胞结合其特征 蛋白质产品 此外，int-1的靶细胞特异性 将通过感染多种细胞类型来研究其作用 携带该基因的逆转录病毒载体。 作为迈向 研究INT-1作用机制的远端阶段， 将尝试分离抗int-PCR的突变细胞系， 1转型。 我们还将进行功能的直接测试， int-1和其他致癌基因之间的合作 乳腺肿瘤发生，并确定是否基于 DNA转移到部分转化的乳腺上皮细胞 细胞可以用来鉴定新的致癌基因， 肿瘤形成 小鼠乳腺癌提供了一个模型 研究上皮细胞中癌基因作用的系统： int-1在这些肿瘤中的作用可能揭示了 与其他上皮肿瘤相关的致癌作用，包括 人类癌症

The int-1 gene is activated by insertions of mouse mammary tumor virus (MMTV) proviral DNA in MMTV-induced tumors and its protein product is strongly implicated in tumorigenesis. The gene has transforming activity in certain mammary epithelial cell lines but not in fibroblasts. int-1 is also implicated in the development of the central nervous system in mid-gestational mouse embryos. Recent data suggest that int-1 protein products may enter the secretory pathway, and that the gene may act via secretion of a diffusible factor. The purpose of this research is to investigate the mechanism of int-1 mediated transformation, and the role of this gene in the pathway of tumorigenesis. Specifically, we shall test the hypothesis that int-1 encodes a novel growth factor. Polyclonal antibodies will be raised against int-1 fusion proteins expressed in E. coli, and used for detection of secreted forms of int-1 protein in cell culture medium. We shall also seek evidence of an int-1 dependent secreted factor by means of its predicted mitogenic activity on approriate mammary cells. In order to begin a functional analysis of int-1 proteins, specific deletions and site-directed mutations will be generated in int-1; their biological activities will then be tested in int-1 responsive cells in conjunction with characterization of their protein products. In addition, the target cell specificity of int-1 action will be investigated by infecting a variety of cell types with retroviral vectors carrying the gene. As a step towards investigating distal stages in the mechanism of int-1 action, attempts will be made to isolate mutant cell lines resistant to int- 1 transformation. We shall also perform direct tests of functional cooperation between int-1 and other oncogenes implicated in mammary tumorigenesis, and determine whether an assay based on DNA transfer into partially transformed mammary epithelial cells can be used to identify novel oncogenes that contribute to tumor formation. Mouse mammary carcinomas provide a model system for studying oncogene action in epithelial cells: studies of the role of int-1 in these tumors may reveal novel mechanisms of carcinogenesis with relevance to other epithelial tumors including human cancers.