DIFFERENTIATION OF MEDULLARY THYROID CARCINOMA CELLS

本申请中的研究试图阐明对 正常降钙素产生甲状腺C- 细胞和它们的肿瘤对应物，甲状腺髓样癌（MTC）。 了解这种控制可以提供重要的洞察力， 肿瘤的发生和发展。 甲状腺髓样癌是一个很好的 本研究的模型，因为定义的进展阶段，其中涉及 神经内分泌分化功能丧失，包括 降钙素的生产，已经确定。 我们已经开发出一种体外 系统研究MTC分化和进展的步骤。 MTC小区 文化可以根据许多特征进行区分， 正常C细胞，包括降钙素基因表达增加， 化学方法或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，集中在调节的分子机制， 诱导分化 建议的研究不仅重要， 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， 在细胞中发挥作用。 1. 内源性ras癌基因在MTC细胞分化中的作用， 可以通过实施几种策略来阻断ras基因功能来研究。 此外，在正常和非正常组织中， 增生的C细胞，以及分化良好和分化不良的C细胞 不同的MTC，将被检查。 二是将决心 ras基因表达后是否检测到信号转导改变 在MTC小区中的插入，足以诱导所有或部分的 ras介导的分化表型。 ras介导的一般性 将使用两种新的人MTC细胞来检查MTC细胞中的分化。 行，以确定是否存在MTC的亚型，不同的是， 回答RAS。 这些亚型可以识别其他涉及的遗传事件 在C细胞分化或MTC肿瘤进展中。 2. 降钙素基因中的ras反应性转录元件将是 通过继续分离DNA结合， 蛋白质及其基因。 调节这些蛋白质的表达，如 以及它们在MTC和其他细胞体外分化中的功能， 在体内，将被检查。

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.