Role of Protein Kinase C in Colon Carcinogenesis

描述（由申请人提供）：结肠癌是美国癌症死亡的第二大原因。它是通过一个多步骤的过程产生的，涉及调节上皮细胞增殖、分化和存活的信号通路的进行性变化。PKC β II诱导结肠过度增殖，并且是体内结肠癌发生的早期步骤所需的。PKC β II通过激活一个新的PKC β II->考克斯-2-> TGF β RII信号传导轴诱导大鼠肠上皮（RIE）细胞对TGF β生长抑制作用的抵抗。PKC β II还通过激活PKC β II->Ras/Mek->PKCI/Rac 1信号通路在RIE细胞中诱导侵袭性表型。在这个提议中要测试的总体假设是PKC β II是人结肠癌细胞中转化表型所必需的。目的1验证PKC β II通过激活PKC β II->考克斯-->？TGF β RII信号轴。目的2：验证PKC β II在体外对人结肠癌细胞的非贴壁依赖性生长和侵袭以及体内致瘤性和转移的重要性。还将在人结肠癌中评估PKC β II表达并与临床结果进行比较。目的3将使用与PKC β KO小鼠杂交的两个互补转基因K-Ras小鼠模型来检验PKC II是K-Ras介导的体内结肠癌发生所需的假设。目的4将验证PKC β II和PKC/I协同促进体内结肠癌发生的假设。将在与表达激酶缺陷型PKC/I的转基因小鼠杂交的转基因PKC β II小鼠中评估PKC/I在PKC β II介导的结肠癌发生中的作用。将在与表达组成型活性PKC/I的小鼠杂交的转基因PKC β II小鼠中评估PKC β II和PKC/I在结肠癌进展、侵袭和转移中的协同作用。这些研究将确定PKC β II在人结肠癌细胞转化中的作用，PKC β/II促进细胞转化的信号传导机制，以及PKC β II、PKC？和致癌K-Ras在体内促进结肠癌发生。他们还将评估PKCbetaII作为结肠癌潜在的治疗靶点和预后标志物，并开发新的结肠癌遗传模型，这些模型可能适用于研究从启动到体内浸润性癌的结肠癌发生的所有阶段。

DESCRIPTION (provided by applicant): Colon cancer is the second leading cause of cancer death in the United States. It arises by a multi-step process involving progressive changes in signaling pathways that regulate epithelial cell proliferation, differentiation and survival. PKCbetaII induces hyperproliferation in the colon, and is required for early steps in colon carcinogenesis in vivo. PKCbetaII induces resistance to the growth inhibitory effects of TGFbeta in rat intestinal epithelial (RIE) cells through activation of a novel PKCbetaII->Cox-2->TGFbetaRII signaling axis. PKCbetaII also induces an invasive phenotype in RIE cells through activation of a PKCbetaII->Ras/Mek->PKCI/Rac1 signaling pathway. The overall hypothesis to be tested in this proposal is that PKCbetaII is required for the transformed phenotype in human colon cancer cells. Aim 1 will test the hypothesis that PKCbetaII confers TGFbeta resistance on human colon cancer cells by activating the PKCbetaII->Cox-->?TGFbetaRII signaling axis. Aim 2 will test the hypothesis that PKCbetaII is important for anchorage-independent growth and invasion of human colon cancer cells in vitro, and for tumorigenicity and metastasis in vivo. PKCbetaII expression will also be assessed in human colon cancers and compared with clinical outcome. Aim 3 will test the hypothesis that PKCII is required for K-Ras-mediated colon carcinogenesis in vivo using two complementary transgenic K-Ras mouse models crossed to PKCbeta KO mice. Aim 4 will test the hypothesis that PKCbetaII and PKC/I collaborate to promote colon carcinogenesis in vivo. The role of PKC/I in PKCbetaII-mediated colon carcinogenesis will be assessed in transgenic PKCbetaII mice crossed to transgenic mice expressing kinase-deficient PKC/I. Synergism between PKCbetaII and PKC/I in colon cancer progression, invasion and metastasis will be assessed in transgenic PKCbetaII mice crossed to mice expressing constitutively-active PKC/I. These studies will determine the role of PKCbetaII in human colon cancer cell transformation, the signaling mechanisms by which PKCbeta/II contributes to cellular transformation, and the relationship between PKCbetaII, PKC? and oncogenic K-Ras in promoting colon carcinogenesis in vivo. They will also assess PKCbetaII as a potential therapeutic target and prognostic marker in colon cancer, and develop new genetic models of colon cancer that may be suitable for studying all stages of colon carcinogenesis from initiation to invasive carcinoma in vivo.