Molecular Mechanisms for Growth Factor Action of Gastrin

描述(申请人摘要)：尽管被描述为兴奋剂 胃酸分泌，肽类激素胃泌素也发挥作用 对正常和恶性胃肠道组织的促生长作用。 虽然大量的研究已经阐明了导致 胃泌素促进胃酸分泌的分子机制 调节胃泌素生长因子作用的事件 有部分特征的。胃泌素对大鼠胰腺生长的促进作用 通过激活ERKs和早期细胞外信号通路诱导的腺癌细胞(AR4-2J) 反应基因c-fos。此外，调查人员最近观察到， 胃泌素是一种有效的细胞凋亡抑制因子。因此，托迪斯科博士 推测胃泌素的生理功能之一是刺激 无论是细胞生长还是生存。这个应用程序的总体目标是 剖析促生长和促进生长的分子机制。 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，申请者将 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，研究人员将利用荧光素酶 由几个DNA调节元件组成的报告基因构建 C-fos基因的启动子。特别是，调查员将研究 ERKs和p38激酶在c-fos调控中的作用 抄写。额外的实验将重点放在小的角色上 胃泌素信号转导c-fos和in中的GTP结合蛋白RAS、RAC和CDC42 AR4-2J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负性基因转移 将Ras、Rac和CDC42突变体导入AR4-2J细胞，以达到高表达 这些GTP酶的表达水平。在第二个具体目标中，托迪斯科博士 将调查负责的信号转导通路 胃泌素在AR4-2J细胞和胃中的抗凋亡作用 壁细胞。这些研究将集中在分子机制上。 调节胃泌素对蛋白激酶AKT的诱导，已知促进 细胞在多个系统中存活。AKT激酶在抗细胞凋亡中的作用 胃泌素的作用将通过腺病毒介导的基因转移进行评估 AKT的显性负性突变体。通过这些研究，调查人员希望 不仅在生理学和细胞学以及 分子生物学，而且在临床医学领域， 普普利坎特认为，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药物的应用 在治疗人类疾病方面。

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.