DIFFERENTIATION OF MEDULLARY THYROID CARCINOMA CELLS

本申请中的研究试图阐明对 正常降钙素分泌甲状腺激素的神经内分泌分化 细胞和它们的肿瘤对应物，甲状腺髓样癌(MTC)。 了解此控件可以为 肿瘤的发生和发展。甲状腺髓样癌是一种很好的 这项研究的模型，因为确定的进展阶段包括 神经内分泌分化功能丧失，包括 降钙素的产生，已经被确定。我们已经开发出一种体外培养技术 系统研究MTC分化和进展的步骤。中的MTC细胞 文化可以从许多特征上加以区分 包括降钙素基因表达增强的正常C细胞 化学方法或通过ras癌基因导入。目前的提案将 通过细胞生物学、生物化学和 分子生物学，专注于调节细胞周期的分子机制。 诱导分化。建议的研究不仅重要，而且 用于识别可能参与神经内分泌的过程 为进一步阐明ras癌基因的作用机制 在单元格中发挥作用。 1.内源性ras癌基因在MTC细胞分化中的作用 通过执行几个动作来阻断ras基因的功能来进行研究。 此外，正常组和对照组的内源性ras蛋白表达水平 增生的C细胞，以及分化良好和分化较差的 差异化的MTC，将被检验。第二，将确定 Ras基因后是否检测到信号转导改变 在MTC细胞中的插入足以诱导全部或部分 Ras介导的分化表型。RAS介导的概括性 将使用两个新的人类MTC细胞来检测MTC细胞的分化 行，以确定MTC的子类型是否存在，不同于它们的 对RAS的反应。这样的亚型可能识别涉及的其他遗传事件 在C细胞分化或MTC肿瘤进展中。 2.降钙素基因中的ras反应转录元件将是 进一步的特征是，通过继续分离DNA结合 蛋白质及其基因。调节这些蛋白的表达，如 以及它们在MTC和其他细胞体外分化中的作用， 在活体内，将进行检查。

The studies in this application seek to elucidate the control of neuroendocrine differentiation in normal calcitonin producing thyroid C- cells and their neoplastic counterpart, medullary thyroid carcinoma (MTC). Understanding this control could provide important insight for events in tumor development and progression. Medullary thyroid carcinoma is a good model for this study, since defined stages of progression which involve loss of neuroendocrine differentiation features including capacity for calcitonin production, have been identified. We have developed an in vitro system to study steps of MTC differentiation and progression. MTC cells in culture can be differentiated with respect to many characteristics of normal C-cells including increased calcitonin gene expression, either chemically or by ras oncogene introduction. The current proposal will further characterize these findings, by cell biology, biochemistry, and molecular biology, concentrating on the molecular mechanisms regulating the induced differentiation. The studies proposed will be important not only for identifying the processes which may be involved in neuroendocrine differentiation, and for further elucidating the mechanisms of ras oncogene function in cells. 1. The role of endogenous ras oncogenes in MTC cell differentiation will be investigated by performing several maneuvers to block ras gene function. In addition, the levels of endogenous ras protein expression in normal and hyperplastic C cells, as well as well-differentiated and poorly differentiated MTC, will be examined. Second, it will be determined whether the signal transduction alterations detected following ras gene insertion in MTC cells, are sufficient to induce all or part of the differentiated phenotype mediated by ras. The generality of ras-mediated differentiation in MTC cells will be examined, using two new human MTC cell lines, to determine whether subtypes of MTC exist, differing in their response to ras. Such subtypes may identify other genetic events involved in C-cell differentiation or MTC tumor progression. 2. A ras-responsive transcriptional element in the calcitonin gene will be further characterized, by continuing our isolation of the DNA binding proteins and their genes. Regulation of expression of these proteins, as well as their function in differentiation of MTC and other cells in vitro, and in vivo, will be examined.