FUNCTIONAL STUDY OF A CARCINOMA ASSOCIATED MUCIN MUC1

我们的目标是建立MUC 1粘蛋白在肿瘤发生和转移中的分子基础。MUC 1是一种细胞相关的粘蛋白糖蛋白，在90%以上的癌和转移性病变中高度过表达。 我们发现，缺乏Muc 1的小鼠自发性乳腺肿瘤在肿瘤生长率和转移方面具有非常显著的降低。 我们的假设是MUC 1是一种多功能蛋白，其结构特征有助于其调节肿瘤进展和转移的能力。 一个结构特征是棒状的、密集糖基化的细胞外结构域，其调节肿瘤细胞的增殖和它们对免疫效应细胞的脆弱性。第二个结构特征是酪氨酸磷酸化的胞质尾区，其与参与信号转导和细胞骨架重组的蛋白质相互作用。 为了验证我们的假设，在目标1中，我们将在小鼠乳腺中过表达人MUC 1蛋白，直接模拟人乳腺癌中MUC 1过表达的表型。 将研究正常腺体的发育。 将这些小鼠与发生自发性乳腺癌的MMTV-MTag和MMTV-c-neu小鼠杂交，并检查双转基因小鼠MUC 1过表达的影响。 我们将监测肿瘤进展和转移。 2)为了研究MUC 1结构域的功能意义，我们将在正常腺体和肿瘤中缺失各种结构域（串联重复序列、细胞外和细胞质结构域）的转基因小鼠中过表达MUC 1，以测试这些区域在肿瘤发生和发展中的功能。 3)我们将使用酵母双杂交技术和免疫共沉淀实验鉴定与MUC 1相互作用的蛋白质，并表征MUC 1与参与信号转导和细胞骨架组织的细胞质蛋白相互作用的分子细节和后果。 计划中的实验将增加我们对MUC 1如何通过其杆状细胞外结构域以及通过胞质结构域与参与信号转导的蛋白质的相互作用来调节肿瘤进展和转移的理解。

Our objective is to establish the molecular basis for the contribution of the MUC1 mucin to tumorigenesis and metastasis. MUC1 is a cell associated mucin glycoprotein that is highly overexpressed in greater than 90 percent of carcinomas and metastatic lesions. We showed that spontaneous mammary gland tumors in mice lacking Muc1 had highly significant decreases in tumor growth rate and metastasis. Our hypothesis is that MUC1 is a multi-functional protein with structural features that contribute to its ability to modulate tumor progression and metastasis. One structural feature is the rodlike, densely glycosylated extracellular domain that modulates the adhesiveness of tumor cells and their vulnerability to immune effector cells. The second structural feature is the tyrosine phosphorylated cytoplasmic tail domain that interacts with proteins involved in signal transduction and cytoskeletal reorganization. To test our hypothesis, in aim 1 we will overexpress the human MUC1 protein in mammary glands of mice, directly mimicking the phenotype of MUC1 overexpression in human breast cancer. Development in the normal glands will be studied. These mice will be crossed with MMTV-MTag and MMTV-c-neu mice that develop spontaneous breast cancer and the bitransgenics will be examined for the effects of MUC1 overexpression. We will monitor tumor progression and metastasis. 2) To examine the functional significance of the MUC1 domains, we will overexpress MUC1 in transgenic mice with various domains deleted (tandem repeats, extracellular, and cytoplasmic domains) in normal glands and tumors to test the functions of these regions in tumorigenesis and development. 3) We will identify proteins interacting with MUC1 using the yeast two-hybrid technique and coimmunoprecipitation experiments and characterize the molecular details and consequences of MUC1 interactions with cytoplasmic proteins involved in signal transduction and cytoskeletal organization. The planned experiments will add to our understanding of how MUC1 modulates tumor progression and metastasis by virtue of its rodlike extracellular domains as well as through interactions of the cytoplasmic domain with proteins that are involved in signal transduction.