GI HORMONES IN NORMAL AND NEOPLASTIC GUT AND PANCREAS

正常和肿瘤性肠道和胰腺中的胃肠道激素

• 批准号: 6217566
• 负责人: Courtney M Townsend
• 金额: $ 11.71万
• 依托单位: UNIVERSITY OF TEXAS MED BR GALVESTON
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-30 至 2000-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6217566
• 关键词: athymic mouse; biological signal transduction; bombesin; carcinogenesis inhibitor; cell cycle; cell growth regulation; cyclins; gastrointestinal hormones; gastrointestinal system; gene expression; gene targeting; hormone inhibitor; hormone receptor; hormone regulation /control mechanism; hormone related neoplasm /cancer; neoplastic growth; northern blottings; nuclear runoff assay; ornithine decarboxylase; pancreas; pancreas neoplasms; radioimmunoassay; stomach neoplasms; tissue /cell culture; western blottings

Bombesin (BBS) and its mammalian counterpart, gastrin-releasing peptide (GRP) are important peptides that affect numerous aspects of intestinal function that include: 1) stimulation of peptide release, 2) increase in gene expression, and 3) stimulation of normal and neoplastic gut growth. Receptors that bind BBS are members of the G protein receptor superfamily and include the GRP-receptor (GRP-R) and the neuromedin-B receptor (NMB- R). Key questions remain that are crucial for understanding the biologic effects of BBS, in particular, and all GI hormones, in general. They include, what are the mechanisms that regulate the diverse cellular functions produced by a peptide when it binds to its receptor and are identical or separate second messenger pathways responsible for peptide release, alterations in gene expression and cell growth? The major focus of this project is to define the intracellular mechanisms that regulate the multiple biologic effects of BBS in the gut. To accomplish this goal we have established a unique cell model by transfection of functional BBS receptors into our previously-characterized human endocrine cell line, BON, which produces the hormones neurotensin (NT), chromogranin A (CGA) and pancreastatin. Our preliminary findings demonstrate that BBS increases peptide release, alters NT gene expression and stimulates cell growth of these BON transfectants. In addition, we show that BBS stimulates the growth of the human gastric cancer cell line SIIA through a receptor other than GRP-R or NMB-R. Furthermore, our in vivo studies demonstrate that BBS affects normal and neoplastic gut tissues in a differential and cell-specific fashion. Taken together, these results indicate that BBS acts through multiple cell-specific signal transduction pathways to regulate cellular function. Based upon our findings, the central hypothesis of this proposal is that GI hormones regulate peptide release, gene expression and growth through specific receptors and post- receptor mechanisms. To examine this hypothesis we have planned experiments with the following Specific Aims: 1) We will characterize signal transduction pathways through which BBS regulates hormone secretion. To accomplish this goal, we will use our transfected BON cell clones to further delineate, in a systematic fashion, the specific signal transduction pathways responsible for BBS-mediated hormone release. 2) We will determine the cellular factors important for BBS-mediated changes in peptide gene expression. To accomplish this goal, we will identify the mechanisms responsible for BBS-mediated increases in NT gene expression. 3) We will examine the receptors and intracellular mechanisms responsible for the trophic effects of BBS. To accomplish this goal, we will assess the effects of BBS on our cell-established models of BBS-mediated cellular proliferation. The long-term goal of this proposal is to systematically define the intracellular mechanisms that regulate the cellular effects of BBS utilizing novel cell model systems that have been established in our laboratory. An in-depth identification of the signal transduction systems and molecular mechanisms that are responsible for these multiple cellular functions are crucial to our overall understanding of the diverse biologic effects exerted by the GI hormones.

蛙皮素(BBS)及其哺乳动物的胃泌素释放肽 (GRP)是影响肠道许多方面的重要多肽。 功能包括：1)刺激多肽释放，2)增加 基因表达，以及3)刺激正常和肿瘤肠道生长。 结合BBS的受体是G蛋白受体超家族的成员 包括GRP受体(GRP-R)和神经介素B受体(NMB-R)。 r)。关键问题仍然存在，这些问题对于理解生物 特别是BBS的影响，以及所有胃肠道激素的影响。他们 包括，是什么机制调节不同的细胞 当一个肽与其受体结合时产生的功能 负责多肽的相同或不同的第二信使通路 释放，基因表达和细胞生长的变化？主要关注点 这个项目的目的是定义细胞内调控机制 BBS在肠道中的多种生物学效应。要实现这一目标 我们通过转导功能性BBS建立了一种独特的细胞模型 我们之前描述的人类内分泌细胞系中的受体， 产生神经降压素(NT)和嗜铬粒素A(CGA)的Bon 和胰岛抑素。我们的初步调查结果表明，BBS 增加多肽释放，改变NT基因表达，刺激细胞 这些Bon转染体的生长情况。此外，我们还展示了BBS 通过促进人胃癌细胞系SIIA的生长 GRP-R或NMB-R以外的受体。此外，我们的活体研究 证明BBS影响正常和肿瘤的肠道组织 差异化和特定于细胞的时尚。综合来看，这些结果 提示BBS通过多种细胞特异性信号转导途径发挥作用 调节细胞功能的途径。根据我们的发现， 这一提议的中心假设是胃肠激素调节多肽 释放，基因表达和生长通过特定的受体和后 受体机制。为了检验这一假设，我们计划 有以下具体目标的实验：1)我们将表征 BBS调节激素的信号转导途径 分泌物。为了实现这一目标，我们将使用我们的转基因Bon细胞 克隆以系统的方式进一步描绘特定的信号 负责BBS介导的激素释放的信号转导途径。2) 我们将确定对BBS介导的变化至关重要的细胞因素 在多肽基因表达上。为了实现这一目标，我们将确定 BBS介导NT基因表达增加的机制。 3)我们将研究负责的受体和细胞内机制 对于BBS的营养作用。为了实现这一目标，我们将评估 BBS对我们细胞建立的BBS介导的模型的影响 细胞增殖。这项提议的长期目标是 系统地定义调节细胞内的机制 使用新的细胞模型系统的BBS的细胞效应 在我们的实验室建立。对信号的深入识别 转导系统和分子机制负责 这些多种细胞功能对我们的整体 了解胃肠激素所产生的不同生物学效应。