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）确定信号转导分子的蛋白激酶C（PKC）家族的单个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。该更新申请借鉴了新的信息，这些信息表明PKC/PKC α信号传导触发肠上皮细胞中细胞周期退出的协调程序，PKC α活性调节该系统中的存活途径，PKC α信号传导的脱敏似乎是肠致癌的重要组成部分，并且PKC/PKC α表达/活性的丧失促进肠细胞的生长。基于这些发现，本申请提出了策略来检验以下假设：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/表达的特定改变在肠道肿瘤的发展中发挥着关键作用。因此，PKC α功能的恢复可能有利于肠道肿瘤的预防和/或治疗。为了检验这一假设，将讨论以下具体目标：（1）确定肠上皮细胞中PKC/PKC α信号转导对p21 waf 1/cip 1转录诱导的机制，并确定肿瘤性肠细胞中PKC α信号转导下游的p21 waf 1/cip 1调节途径是否改变，（2）确定PKC α信号在肠上皮细胞存活调节中的作用。（3）明确PKC α表达缺失在肠癌发生过程中的分子机制。和（4）探索在结肠癌中具有有希望的预防和治疗活性的分化剂的潜力（即，类维生素A、维生素D）以恢复肿瘤肠细胞中PKC α的表达。这些研究有望增强我们对调控肠上皮更新过程的信号通路的理解，并突出PKC信号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.