Role of Protein Kinase C Iota in Colon Carcinogenesis

描述(申请人提供)：结肠癌是由进展性疾病引起的 正常生长抑制、分化和细胞凋亡的失调 结肠上皮细胞中的信号。我们的长期目标是了解 蛋白激酶C同工酶在结肠上皮细胞生物学和生物学中的作用 结肠癌的发生。多条证据表明，非典型的PKC IOTA异构体(PKCi)在结肠癌的发生过程中起着重要的促进作用。 首先，PKC在结肠癌中的表达高于未受累的结肠癌 结肠上皮。第二，PKCi的表达对癌细胞具有保护作用 通过激活核因子-kB诱导细胞凋亡。第三，PKCI在 癌基因RAS活化对肠上皮细胞的转化作用 在结肠癌中常见的突变。第四，对PKCi活性的抑制 饮食中的omega-3脂肪酸与阿司匹林的防癌效果相关 欧米茄-3脂肪酸。这些数据加在一起表明PKCi起着关键作用 通过提高细胞存活率在结肠癌发生中的作用。我们假设 PKCi保护结肠上皮细胞抗凋亡及升高的PKCi 会导致对结肠的易感性增加 致癌。我们已经培育出了具有结构性表达的转基因小鼠。 结肠中PKCi的活性(Ca)或显性-阴性(DN)突变形式 上皮细胞，并检测到结肠的基础细胞凋亡减少 表达CaPKCi的小鼠上皮细胞。在具体目标1中，我们将确定 进一步研究PKCi在结肠上皮细胞动态平衡中的作用 我们的caPKCi和dnPKCi转基因小鼠。具体目标2将评估 PKCI介导K-ras对结肠上皮细胞动态平衡的影响 和体内结肠癌的发生。具体目标3将决定 PKCI在RAS转化和肠上皮细胞核因子-kB信号转导中的作用 在体外和体内的结肠上皮细胞中。具体目标4将评估 PKCi在膳食脂肪介导的结肠上皮细胞改变中的作用 动态平衡与结肠癌发生。这些目标将通过以下途径实现 互补转基因小鼠和大鼠肠上皮细胞的应用 评估PKCi在结肠上皮细胞中功能的模型。

DESCRIPTION (provided by applicant): Colon cancer results from progressive disregulation of the normal growth inhibitory, differentiation and apoptotic signals in colonic epithelial cells. Our long-term goal is to understand the role of protein kinase C (PKC) isozymes in colonic epithelial cell biology and colon carcinogenesis. Several lines of evidence suggest that the atypical PKC iota isoform (PKCi) plays an important promotive role in colon carcinogenesis. First, PKC expression is elevated in colon tumors relative to uninvolved colonic epithelium. Second, expression of PKCi protects cancer cells from apoptosis by activating NF-kB. Third, PKCi plays a requisite role in the transformation of intestinal epithelial cells by activated Ras, an oncogene commonly mutated in colon cancer. Fourth, inhibition of PKCi activity by dietary omega-3 fatty acids correlates with the cancer-preventive effects of omega-3 fatty acids. Taken together these data indicate that PKCi plays a key role in colon carcinogenesis by enhancing cell survival. We hypothesize that PKCi protects colonic epithelial cells against apoptosis and that elevated PKCi in the colonic epithelium will result in an increased susceptibility to colon carcinogenesis. We have generated transgenic mice that express constitutively active (ca) or dominant-negative (dn) mutant forms of PKCi in the colonic epithelium and have detected a decrease in basal apoptosis in the colonic epithelium of mice expressing caPKCi. In Specific Aim 1, we will determine the role of PKCi in colonic epithelial cell homeostasis by further characterizing our caPKCi and dnPKCi transgenic mice. Specific Aim 2 will assess the role of PKCi in mediating the effects of K-ras on colonic epithelial cell homeostasis and colon carcinogenesis in-vivo. Specific Aim 3 will determine the role of PKCi in Ras transformation and NF-kB signaling in intestinal epithelial cells in-vitro and in the colonic epithelium in-vivo. Specific Aim 4 will assess the role of PKCi in dietary fat-mediated changes in colonic epithelial cell homeostasis and colon carcinogenesis. These aims will be accomplished through the use of complementary transgenic mouse and rat intestinal epithelial cell models to assess the function of PKCi in the colonic epithelium.