Molecular Mechanisms for Growth Factor Action of Gastrin

描述（申请人的摘要）：尽管其特征在于作为一种兴奋剂， 胃酸分泌，肽激素胃泌素也发挥作用 对正常和恶性胃肠道组织的生长促进作用。 虽然许多研究已经阐明了负责 胃泌素对胃酸分泌的刺激作用， 调节胃泌素的生长因子作用的事件仅仅是 部分特征。胃泌素促进大鼠胰腺生长 腺癌细胞（AR 4 - 2 J）通过激活ERK和早期 反应基因c-fos。此外，调查人员最近观察到， 胃泌素是细胞凋亡的有效抑制剂。因此，托迪斯科博士 推测胃泌素的生理功能之一是刺激 细胞生长和存活。此应用程序的总体目标是 剖析介导促生长的分子机制， 胃泌素对胰腺癌细胞和胃癌细胞的抗凋亡作用 壁细胞作为模型。在第一个具体目标中，申请人将 探讨胃泌素对早期反应基因表达的影响 c-fos对于这些实验，研究者将利用荧光素酶 报道基因构建体，其包含存在于 c-fos基因的启动子。特别是，研究人员将研究 ERK和p38激酶在c-fos调控中的作用 转录。更多的实验将集中在小的作用， GTP结合蛋白Ras、Rac和Cdc 42在胃泌素向c-fos的信号传导和 AR 4 - 2 J细胞生长的调控。对于这些实验，研究人员 将利用腺病毒介导的显性阴性基因转移 将Ras、Rac和Cdc 4 - 2的突变体导入AR 4 - 2 J细胞，以实现高表达。 这些GTP酶的表达水平。在第二个具体目标中，托迪斯科博士 将研究信号转导途径， 胃泌素在AR 4 - 2 J细胞和胃粘膜中的抗凋亡作用 壁细胞这些研究将集中在分子机制， 调节胃泌素对蛋白激酶AKT的诱导，已知AKT促进 细胞在多个系统中存活。AKT激酶在抗凋亡中的作用 胃泌素的作用将通过腺病毒介导的基因转移来评估， AKT的显性负突变体。通过这些研究，研究人员希望 不仅在生理学和细胞学领域， 分子生物学，而且在临床医学的竞技场， appllicant认为，这些研究可能有助于 选择性胃泌素激动剂和拮抗剂作为治疗剂的应用 治疗人类疾病。

DESCRIPTION (Applicant's Abstract): Although characterized as a stimulant of gastric acid secretion, the peptide hormone gastrin also exerts growth-promoting effects on normal and malignant gastrointestinal tissues. While numerous studies have elucidated the mechanisms that are responsible for the stimulatory effect of gastrin on gastric acid secretion, the molecular events that mediate the growth factor action of gastrin have been only partially characterized. Gastrin stimulates the growth of rat pancreatic adenocarcinoma cells (AR4-2J) through activation of the ERKs and of the early response gene c-fos. In addition, the investigator has recently observed that gastrin is a potent inhibitor of cellular apoptosis. Accordingly, Dr. Todisco speculates that one of the physiological functions of gastrin is to stimulate both cellular growth and survival. The overall goal of this application will be to dissect the molecular mechanisms that mediate the growth promoting and anti-apoptotic effects of gastrin using pancreatic cancer cells and gastric parietal cells, as models. In the first specific aim, the applicant will investigate the effect of gastrin on the expression of the early response genes c-fos. For these experiments the investigator will take advantage of luciferase reporter gene constructs comprising several DNA-regulatory elements present in the promoters of the c-fos gene. In particular, the investigator will study the function of the ERKs and of p38 kinase in the regulation of c-fos transcription. Additional experiments will be focused on the role of the small GTP-binding proteins Ras, Rac and Cdc 42 in gastrin signaling to c-fos and in the regulation of AR4-2J cell growth. For these experiments the investigator will take advantage of adenoviral mediated gene transfer of dominant negative mutants of Ras, Rac and Cdc 42 into the AR4-2J cells, in order to achieve high levels of expression of these GTP-ases. In the second specific aim, Dr. Todisco will investigate the signal transduction pathways responsible for the anti-apoptotic effect of gastrin in both the AR4-2J cells and in the gastric parietal cells. These studies will be focused on the molecular mechanism that regulate gastrin induction of the protein kinase AKT that is known to promote cell survival in multiple systems. The role of AKT kinase in the anti-apoptotic effect of gastrin will be assessed by adenoviral mediated gene transfer of dominant negative mutants of AKT. Through these studies, the investigator hopes to shed new knowledge not only in the areas of physiology and cellular and molecular biology, but also in the arena of clinical medicine as, the appllicant believes that the studies may contribute to the rationale for application of selective gastrin agonists and antagonists as therapeutic agents in treatment of human diseases.