MODULATION OF HORMONE RESPONSIVE SYSTEMS BY RAS ONCOGENE PRODUCT

我们研究的目标是了解信号的调制 转导机制在表达过程中明确 致癌基因。我们之前的发现是肾脏的ras转化 细胞系(MDCK细胞)导致对葡萄糖的敏感性丧失， 提高ras产物在激素信号中的可能作用 转导。从我们的研究和其他方面来看，已经表明 RAS转换不仅影响循环AMP介导的信号，它 还能提高肌醇水平，并取消某些功能 EGF的基因。为了考察两者之间的因果关系 Ras基因的表达与信号的各种变化 转导，已经采取了一种新的方法来允许更精确的 控制p21的生产。我们已经获得了一种转染剂 含mmtv ltr ras癌基因的NIH-3T3细胞株。我们的 初步结果表明，在地塞米松存在的情况下， 培养，当产生p21时，伴随着 转染组3T3细胞的EGF结合，而细胞内 环磷酸腺苷介导的激素反应不那么明显。拉斯维加斯- -已知转化的细胞具有升高的 二酰甘油，EGF结合丧失是否为后果 蛋白激酶C的激活机制正在研究中。这一发现 与我们之前的观察一致，在RAS中- 转化3T3细胞后，EGF结合力明显降低。自.以来 NIH-3T3细胞相对未分化，最好是 检测诱导型ras基因在分化程度更高的肿瘤中的作用 细胞系。我们已经获得了含有糖皮质激素的质粒- 来自他人的可诱导的正常和病毒型RAS。MDCK细胞现在已经 已经用这些质粒进行了转基因。我们目前正在挑选 表达最高诱导性ras基因的克隆。一旦这些 经鉴定后，我们将尝试检测 Ras产物的表达与肿瘤细胞增殖的时间关系 EGF结合减少，磷脂酰肌醇升高， 荷尔蒙反应的变化。

The goal of our research is to understand the modulation of signal transduction mechanisms during the expression of a well-defined oncogene. Our previous finding that ras transformation of a kidney cell line (MDCK cells) leads to loss of glucogan sensitivity, raises a possible role of ras product in hormone signal transduction. From our studies and others, it has been shown that ras transformation not only affects cyclic AMP-mediated signal, it also elevates phosphoinositol level and abolishes certain functions of EGF. In order to examine the causal relationship between the expression of ras gene and the various changes of signal transduction, a new approach has been taken to allow more precise control of the production of p21. We have obtained a transfection NIH-3T3 cell line containing MMTV LTR ras oncogene. Our preliminary results show that in the presence of dexamethasone in culture, when p21 is produced, there is a concomitant decrease in EGF binding of the transfected 3T3 cells, while the changes in cyclic AMP-mediated hormone response is less pronounced. The ras- -transformed cells are known to have an elevated level of diacylglycerol, whether the loss of EGF binding is a consequence of activation of protein kinase C is being studied. This finding is consistent with our previous observation that in a ras- transformed 3T3 cell line, EGF binding is markedly reduced. Since NIH-3T3 cells are relatively undifferentiated, it is desirable to examine the effect of inducible ras gene in a more differentiated cell line. We have obtained plasmids, containing glucocorticoid- inducible normal and viral ras, from others. MDCK cells have now been transfected with these plasmids. We are currently selecting clones expressing the most highly inducible ras gene. Once these transfected clones are identified, we will attempt to examine the temporal relationship between the expression of ras product and the reduction of EGF binding, the elevation of phosphoinositol and the changes in hormone response.