PKC ISOZYMES AND INTESTINAL EPITHELIAL GROWTH CONTROL

描述（由申请人提供）：本申请的长期目标是(a)确定信号转导分子蛋白激酶C （PKC）家族个体成员在调节肠上皮自我更新中的功能，以及(b)确定PKC同工酶信号通路的改变如何促进肠道疾病的发展。这项更新应用利用了新的信息，证明PKC/PKC a信号触发肠上皮细胞细胞周期退出的协调程序，PKC α活性调节该系统的生存途径，PKC a信号的脱敏似乎是肠癌变的重要组成部分，PKC/PKC a表达/活性的丧失促进肠细胞的生长。基于这些发现，本研究提出了一些策略来验证PKC α是调节肠上皮细胞生长和细胞存活的信号通路的关键组成部分，并且该分子活性/表达的特异性改变在肠肿瘤的发展中起关键作用。因此，PKC a功能的恢复可能有利于预防和/或治疗肠道肿瘤。为了验证这一假设，将解决以下具体目标：(1)明确肠上皮细胞中PKC/PKC a信号对p21waf1/cip1转录诱导的机制，并确定肿瘤肠细胞中PKC α信号下游的p21waf1/cip1调控通路是否改变；(2)确定PKC a信号在肠上皮细胞存活调控中的作用；(3)明确肠癌变过程中PKC a表达缺失的分子机制。(4)探索具有结肠癌预防和治疗活性的分化剂（即类维生素a、维生素D）恢复肿瘤肠细胞PKC α表达的潜力。这些研究有望增强我们对肠上皮更新过程的信号通路的理解，并强调PKC信号通路缺陷对肠肿瘤的贡献。

DESCRIPTION (provided by applicant): The long-term goals of this application are (a) to define the function(s) of individual members of the protein kinase C (PKC) family of signal transduction molecules in regulation of intestinal epithelial self-renewal, and (b) to determine how alterations in PKC isozyme signaling pathways contribute to the development of intestinal disease. This renewal application draws on new information demonstrating that PKC/PKC a signaling triggers a coordinated program of cell cycle withdrawal in intestinal epithelial cells, that PKC alpha activity regulates survival pathways in this system, that desensitization of PKC a signaling appears to be an important component of intestinal carcinogenesis, and that loss of PKC/PKC a expression/activity promotes the growth of intestinal cells. Based on these findings, strategies are proposed in this application to test the hypothesis that PKC alpha is a key component of signaling pathways that regulate intestinal epithelial cell growth and cell survival, and that specific alterations in the activity/ expression of this molecule play a pivotal role in the development of intestinal neoplasia. Restoration of PKC a function may thus be of benefit for the prevention and/or therapy of intestinal tumors. To test this hypothesis, the following Specific Aims will be addressed: (1) To define the mechanisms involved in transcriptional induction of p21waf1/cip1 by PKC/PKC a signaling in intestinal epithelial cells and determine if p21waf1/cip1 regulatory pathways downstream of PKC alpha signaling are altered in neoplastic intestinal cells, (2) To determine the role of PKC a signaling in regulation of intestinal epithelial cell survival, (3) To define the molecular mechanisms underlying loss of PKC a expression during intestinal carcinogenesis, and (4) To explore the potential of differentiation agents with promising preventive and therapeutic activity in colon cancer (i.e., retinoids, vitamin D) to restore PKC alpha expression in neoplastic intestinal cells. These studies are expected to enhance our understanding of the signaling pathways that orchestrate the process of intestinal epithelial renewal and highlight the contribution of defects in PKC signaling to intestinal neoplasia.