PROTEIN KINASE C AND COLON CARCINOGENESIS

结肠癌的发生是一个复杂的、多步骤的过程 肠上皮细胞增殖的进行性变化， 分化和程序性死亡。我们的长期目标是 了解蛋白激酶C(PKC)同工酶在肠道中的作用 上皮细胞生物学与结肠癌的发生。几行 有证据表明，PKCβII同工酶(PKC BetaII)参与了 在结肠癌发生中的作用。首先，PKC BetaII的水平和活性是 结肠癌与正常结肠上皮相比升高。 第二，PKCβII参与了结肠癌细胞的增殖 体外培养。第三，高脂肪饮食的成分可以有效地刺激 肠上皮细胞PKCβII活性与结肠癌的关系 致癌。基于这些发现，以及我们的初步研究， 我们假设PKC BetaII直接参与了结肠 致癌。为了直接检验这一假设，我们开发了 表达升高的PKCβII水平的转基因小鼠 肠上皮细胞。在初步研究中，这些小鼠展示了 结肠上皮细胞过度增殖和增加的证据 对致癌物质诱发的结肠癌的易感性。在此应用程序中 我们提出了四个具体目标：1)对三个转基因PKC进行表征 转基因拷贝数、组织分布、表达的BetaII系 PKC BetaII转基因的水平和活性，以及 肠上皮细胞动力学；2)评估转基因PKC BetaII小鼠对致癌物诱导的结肠的易感性增加 癌症；3)确定高脂肪饮食是否会增加易感性 转基因PKC BetaII小鼠与结肠癌的关系；以及4)确定 PKCβII表达升高与功能丧失突变协同作用 APC抑癌基因在促进肠道肿瘤发生中的作用 在APCmin小鼠模型中。这些研究将允许第一个直接 PKCβII在结肠癌中的作用分析 人类疾病的动物模型。

Colon carcinogenesis is a complex, multi-step process involving progressive changes in intestinal epithelial cell proliferation, differentiation and programmed death. Our long-term goal is to understand the role of protein kinase C (PKC) isozymes in intestinal epithelial cell biology and colon carcinogenesis. Several lines of evidence suggest that the PKC betaII isozyme (PKC betaII) is involved in colon carcinogenesis. First, PKC betaII levels and activity are elevated in colon carcinomas compared to normal colonic epithelium. Second, PKC betaII is involved in colon carcinoma cell proliferation in vitro. Third, components of a high fat diet can potently stimulate intestinal epithelial cell PKC betaII activity and promote colon carcinogenesis. Based on these findings, and our preliminary studies, we hypothesize that PKC betaII is directly involved in colon carcinogenesis. To directly test this hypothesis, we developed transgenic mice that express elevated PKC betaII levels in the intestinal epithelium. In preliminary studies, these mice exhibit evidence of colonic epithelial hyperproliferation and an increased susceptibility to carcinogen-induced colon cancer. In this application we propose four specific aims to: 1) characterize three transgenic PKC betaII lines for transgene copy number, tissue distribution, expression level and activity of the PKC betaII transgene, and for changes in intestinal epithelial cytokinetics; 2) assess whether transgenic PKC betaII mice exhibit increased susceptibility to carcinogen-induced colon cancer; 3) determine whether a high fat diet enhances the susceptibility of transgenic PKC betaII mice to colon cancer; and 4) determine whether elevated PKC betaII expression synergizes with loss-of-function mutation of the APC tumor suppressor gene in promoting intestinal tumorigenesis in the APCmin mouse model. These studies will allow the first direct analysis of the role of PKC betaII in colon cancer in two relevant animal models of the human disease.