FUNCTIONAL STUDY OF A CARCINOMA-ASSOCIATED MUCIN MUC-1

我们的目标是了解肿瘤相关粘蛋白MUC1的功能 在乳腺肿瘤的发展中起着重要作用。MUC1蛋白 (also称为PEM，多态性上皮粘蛋白）是一种高度糖基化的 一种高度表达且异常的跨膜粘蛋白糖蛋白， 糖基化被大多数癌，特别是> 92%的 原发性和转移性乳腺癌。MUC1蛋白质是一个大的杆状体， 像分子一样，延伸超过细胞表面250 nm， 经常被唾液酸化。其结构和生化特征可能 使这种蛋白质能够通过掩蔽细胞表面蛋白， 参与粘附或免疫识别的那些。我们的假设是 这种蛋白的表达有利于肿瘤细胞及其转移 这可能是通过降低细胞的粘附特性或通过 在细胞周围提供保护层， 免疫监视MUC1蛋白也存在于顶面 是正常的简单上皮细胞的一部分， 最初出现在器官发生过程中管腔形成的时间 (day 11在老鼠身上）。我们的假设是MUC1可能参与了 上皮的形态发生，可能起到掩盖粘附分子的作用 存在于细胞表面并帮助形成管腔。以来 小鼠中的乳腺癌与人类乳腺癌非常相似， 我们提出的实验将使我们能够分析的功能作用， Muc-I（人基因名称为MUC1;小鼠基因为Muc-1）在 肿瘤的进展和发展。目前的提案将 通过解决以下具体目标直接检验假设： (l)通过在胚胎干细胞中使用基因靶向技术， 具有突变的Muc-I基因的菌株，从而产生缺乏Muc-I的动物 用于测试其在肿瘤进展和发展中的功能的蛋白质（2） 我们将确定Muc-l缺乏对上皮细胞的影响， 器官形成，因为重要的是要了解它的功能，在正常的 组织以及癌症中。(3)我们会让突变小鼠与 转基因小鼠发展乳腺肿瘤或诱发肿瘤， 这些小鼠与化学品或辐射，以确定Muc-l的影响， 缺乏对肿瘤形成和进展（生长和 差异化）。(4)我们会产生转移的肿瘤， 从而能够分析Muc-I蛋白质对细胞增殖速率的影响， 转移、转移的肿瘤百分比和器官特异性 转移性病变(5)我们将检查肿瘤的易感性 在Muc-I缺陷小鼠和对照小鼠中发展至通过免疫细胞裂解 效应细胞（NK细胞和细胞毒性T淋巴细胞）。我们的研究结果应该 与了解更多关于乳腺癌的进展有关 希望最终能更好地调节 疾病

Our goal is to understand the function of the tumor-associated mucin MUC1 in the progression of neoplasia in the mammary gland. The MUC1 protein (also called PEM, polymorphic epithelial mucin) is a heavily glycosylated transmembrane mucin glycoprotein that is highly expressed and aberrantly glycosylated by the majority of carcinomas and in particular, by >92% of primary and metastatic breast cancers. The MUC1 protein is a large, rod- like molecule, extending more than 250 nm beyond the cell surface, and it is often sialylated. The structural and biochemical characteristics may enable this protein to act by masking cell surface proteins, possibly those involved in adhesion or immune recognition. Our hypothesis is that expression of this protein benefits tumor cells and their metastatic counterparts, perhaps by reducing the adhesive properties of cells or by providing a protective layer around cells which may shield them from immune surveillance. MUC1 protein is also present at the apical surfaces of normal simple epithelial cells and is developmentally regulated, appearing initially about the time of lumen formation during organogenesis (day 11 in the mouse). Our hypothesis is that MUC1 may be involved in epithelial morphogenesis, perhaps acting to mask adhesive molecules present on the cell surface and aiding in the formation of a lumen. Since mammary gland cancer in the mouse closely resembles human breast cancer, our proposed experiments will allow us to analyze the functional role of Muc-l (the human gene designation is MUC1; the mouse gene is Muc- l) in the progression of neoplasia and in development. The current proposal will directly test the hypotheses by addressing the following specific aims: (l) By using gene targeting in embryonic stem cells, we will make a mouse strain with a mutated Muc-l gene, thus generating animals lacking Muc-l protein for testing its function in tumor progression and development (2) We will determine the effect of Muc-l deficiency on epithelial organogenesis, since it is important to understand its function in normal tissues as well as in cancer. (3) We will mate the mutant mice with transgenic mice that develop mammary gland tumors or induce tumors in these mice with chemicals or radiation to determine the effect of Muc-l deficiency on tumor formation and progression (growth and differentiation). (4) We will generate tumors that metastasize, thus enabling an analysis of the effect of the Muc-l protein on the rate of metastasis, percentage of tumors that metastasize, and organ specificity of metastatic lesions. (5) We will examine the susceptibility of tumors developing in the Muc-l-deficient and control mice to lysis by immune effector cells (NK cells and cytotoxic T lymphocytes). Our findings should be relevant to understanding more about the progression of breast cancer with the hope, ultimately, of better modulating progression of the disease.