DIFFERENTIATION OF MEDULLARY THYROID CARCINOMA CELLS

该应用程序是我们实验室整体工作的一部分， 它试图阐明神经内分泌的控制 正常甲状腺C细胞和肿瘤C细胞的分化 甲状腺髓样癌（MTC）。 理解 该控制将提供对可以改变哪些功能的把握 在肿瘤的发生和发展中。 甲状腺髓样 癌是这项研究的一个很好的模型，因为确定的阶段 可以识别进展。 我们已经定义了一个体外系统来研究MTC的这些步骤 分化和进展。 培养物中的MTC细胞可以是 与正常C的许多特征不同， 细胞，无论是化学或ras癌基因导入。 myc癌基因又可阻断分化 导论. 本提案将进一步说明这些调查结果， 细胞生物学、生物化学和分子生物学， 分化的机制。 1.正常和激活的细胞rasH癌基因对 将研究MTC细胞分化，以确定 这种效应是否是病毒rasH所特有的。 rasH的影响 对CT基因转录的影响。 的影响 myc癌基因对TT细胞和ras诱导的分化的影响， 被描述。 最后，阻断内源性c- 将使用反义核酸研究rasH和c-myc表达。 核糖核酸 2. ras诱导分化的生化途径和 将通过以下方法研究myc对MTC细胞分化的阻断： 分析信号传导中的几种酶和信使 途径。 识别这些通路中的改变， 分化的细胞，或在分化受阻的细胞中， 在定义控制神经内分泌的过程中很重要 分化 3.控制ras介导的CT诱导的DNA序列 基因表达将被定义，并与序列进行比较， 参与TPA或cAMP诱导的CT基因表达，使用基因 转移和DNA结合测定。 这些相同的测定，沿着 DNA亲和层析，然后将用于部分 纯化ras介导的相关DNA结合蛋白， CT基因诱导。 这项研究对于阐明 ras在细胞中的作用机制。

This application is part of an overall effort of our laboratory, which seeks to elucidate the control of neuroendocrine differentiation in normal thyroid C-cells and their neoplastic counterpart, medullary thyroid carcinoma (MTC). Understanding this control will provide a grasp of what functions may be altered in tumor developement and progression. Medullary thyroid carcinoma is a good model for this study, since defined stages of progression can be identified. We have defined an in vitro system to study these steps of MTC differentiation and progression. MTC cells in culture can be differentiated with respect to many characteristics of normal C- cells, either chemically or by ras oncogene introduction. Differentiation in turn can be blocked by myc oncogene introduction. The current Proposal will further characterize these findings, by cell biology, biochemistry, and molecular biology, concentrating on mechanisms of differentiation. 1. The effects of normal and activated cellular rasH oncogenes on MTC cell differentiation will be investigated, to determine whether the effect is specific to viral rasH. The effects of rasH on CT gene transcription will be ascertained. The effects of the myc oncogen on TT cells, and on ras induced differentiation, will be characterized. Finally, the effects of blocking endogenous c- rasH and c-myc expression will be investigated, using antisense RNA. 2. The biochemical pathway of ras-induced differentiation and myc blocking of differentiation in MTC cells will be studied, by assaying several enzymes and messengers in signal transduction pathways. Identifying alterations in these pathways in differentiated cells, or in cells blocked in differentiation, will be important in defining the processses controlling neuroendocrine differentiation. 3. The DNA sequences controlling ras mediated induction of CT gene expression will be defined, and compared to sequences involved in TPA or cAMP induced CT gene expression, using gene transfer and DNA binding assays. These same assays, along with DNA affinity chromatography, will then be used to partially purify a relevant DNA binding protein involved in ras mediated CT gene induction. This study will be important in elucidating the mechanisms of ras function in cells.