Role of Protein Kinase C Iota in Colon Carcinogenesis

描述（由申请人提供）：结肠癌由进行性 正常生长抑制、分化和凋亡的失调 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（PKC）同工酶在结肠上皮细胞生物学中的作用， 结肠癌发生一些证据表明，非典型PKC iota亚型（PKCi）在结肠癌的发生中起重要的促进作用。 首先，PKC在结肠肿瘤中的表达相对于未受累的结肠肿瘤升高， 结肠上皮第二，PKCi的表达保护癌细胞免于 通过激活NF-κ B诱导凋亡。第三，PKCI在 通过激活的Ras癌基因转化肠上皮细胞 通常在结肠癌中发生突变第四，PKCi活性的抑制， 饮食中的ω-3脂肪酸与癌症预防作用相关， ω-3脂肪酸综合这些数据表明，PKCi在 通过增强细胞存活在结肠癌发生中的作用。我们假设 PKCi保护结肠上皮细胞免于凋亡， 会导致结肠癌易感性增加 致癌作用我们已经产生了转基因小鼠， 结肠中PKCi的活性（ca）或显性阴性（dn）突变形式 并且已经检测到结肠上皮细胞中基础细胞凋亡的减少， 表达caPKCi的小鼠上皮。在具体目标1中，我们将确定 通过进一步表征PKCi在结肠上皮细胞稳态中的作用 我们的caPKCi和dnPKCi转基因小鼠具体目标2将评估 PKCi介导K-ras对结肠上皮细胞稳态的影响 和体内结肠癌发生。具体目标3将决定 PKCi在肠上皮细胞Ras转化和NF-kB信号转导中的作用 在体外和在体内结肠上皮中。具体目标4将评估 蛋白激酶C i在膳食脂肪介导的结肠上皮细胞变化中的作用 稳态和结肠癌发生。这些目标将通过 互补转基因小鼠和大鼠肠上皮细胞的用途 模型来评估PKCi在结肠上皮中的功能。

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.