Ki-Ras Signaling in Pancreatic Cancer: Role of a Novel Akt Regulator

胰腺癌中的 Ki-Ras 信号转导：新型 Akt 调节剂的作用

• 批准号: 8545744
• 负责人: Sushovan Guha
• 金额: $ 18.65万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCI CTR HOUSTON
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-14 至 2015-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8545744
• 关键词: Adenocarcinoma Cell; Adult; Applications Grants; Binding; Biological Assay; CDKN2A gene; Cell Line; Cell Proliferation; Cell Survival; Cells; Clinical Trials; Consensus; Data; Development; Disease; Drug Targeting; Drug resistance; Ductal; Frequencies; Future; Gene Silencing; Goals; Growth Factor; In Vitro; Ki-ras Gene; Laboratories; Lead; Ligands; Link; Malignant Neoplasms; Malignant neoplasm of pancreas; Mediating; Mediator of activation protein; MicroRNAs; Mission; Molecular; Molecular Target; Monomeric GTP-Binding Proteins; Mutation; Oncogenic; Pancreas; Pancreatic Ductal Adenocarcinoma; Pathway interactions; Patients; Pattern; Peptides; Phosphatidylinositols; Phosphoric Monoester Hydrolases; Phosphorylation; Phosphotransferases; Protein Kinase; Proteins; Public Health; RNA Interference; Radiation therapy; Regulation; Reporting; Research; Research Proposals; Resistance; Role; Sampling; Signal Pathway; Signal Transduction; Sirolimus; Survival Rate; System; Testing; Therapeutic; Transducers; Tumor Suppressor Proteins; United States National Institutes of Health; Work; Yeasts; base; cancer prevention; cancer therapy; carcinogenesis; chemotherapy; design; effective therapy; improved; in vivo; inhibitor/antagonist; innovation; knock-down; mTOR Inhibitor; meetings; mortality; mouse model; novel; novel strategies; overexpression; pancreatic cancer cells; pancreatic neoplasm; pancreatic tumorigenesis; receptor; response; small molecule; treatment strategy; tumorigenesis; yeast two hybrid system

DESCRIPTION (provided by applicant): The 5-year survival rate for Pancreatic ductal adenocarcinoma (PDAC) patients is about 5% and has remained largely unchanged over the past 25 years. It is imperative that the mechanisms that underlie this cancer be rapidly identified and investigated so that novel molecular therapies can be developed. For the most part, the signaling mechanisms deregulated in response to genetic alterations in the Ki-Ras gene, and by other well- established hallmarks of pancreatic carcinogenesis, are still incompletely understood. The long-term goal is to elucidate the role and regulation of the phosphoinositide 3-kinase (PI3K) signaling pathway and its protein ki- nase mediator Akt in PDAC and develop more effective antagonists against them for cancer prevention and therapy than are currently available. In pursuit of this goal, a modified yeast two-hybrid screen with Akt as bait helped identify BSTA as a previously unknown mediator of PI3K/Akt signaling. The objective of this proposal is to further understand BSTA regulation and function and the effects of blocking its activity on PDAC. The central hypothesis is that BSTA is a key regulator of oncogenic Ki-Ras-induced Akt signaling and promotes pancreatic tumorigenesis. Based on strong preliminary data, this hypothesis will be tested by pursuing the fol- lowing two specific aims: 1) Identify the mechanism by which Ki-Ras activates Akt; and 2) Investigate the role of BSTA in the resistance of PDAC to mTOR inhibitors in vitro and in vivo. An RNAi-based approach, and pro- tein phosphorylation assays, will be used to test the working hypothesis (Aim 1) that oncogenic Ki-Ras acti- vates Akt in PDAC cells by a) increasing BSTA expression via a mechanism involving the Ral small GTPases and microRNA miR-21, and b) stimulating Akt kinase (mTORC2) and/or suppressing Akt phosphatase (PHLPP) in a BSTA-dependent mechanism. To test if BSTA promotes pancreatic tumorigenesis and drug re- sistance (Aim 2), the minimal Akt-binding sequence on BSTA will be delineated and cell-penetrable peptides designed to test on PDAC cells. BSTA will be also be downregulated in PDAC cells to investigate tumorigene- sis and resistance to mTOR inhibitors in an orthotopic mouse model. The rationale for the proposed project is that understanding the role and regulation of BSTA may help identify novel ways to target the PI3K pathway and oncogenic Ki-Ras signaling for the effective treatment of PDAC. This contribution is significant because it is expected to help reveal details of a novel mechanism by which K-RasG12D additionally controls Akt and lead to the development of alternative pharmacologic strategies for targeting the PI3K/Akt pathway in pancrea- tic ductal cancer. The research proposal is innovative because it describes a novel mechanistic link between oncogenic Ki-Ras and Akt that will, once properly delineated, offer a new and substantially different approach for targeting the PI3K/Akt pathway than currently available. Together, these studies are expected to have a positive impact by fundamentally advancing the understanding of Ki-Ras and PI3K/Akt signaling and uncover new molecular targets for the treatment of pancreatic ductal cancer.

描述(申请人提供)：胰腺导管腺癌(PDAC)患者的5年生存率约为5%，在过去25年中基本保持不变。当务之急是迅速确定这种癌症的潜在机制 并进行研究，以便开发新的分子疗法。在大多数情况下，由于Ki-Ras基因的遗传改变以及其他公认的胰腺癌发生的标志而解除调控的信号机制仍然不完全清楚。其长期目标是阐明磷脂酰肌醇3-激酶(PI3K)信号通路及其蛋白激酶介体Akt在PDAC中的作用和调控，并开发更有效的拮抗剂来预防和治疗癌症。为了实现这一目标，以Akt为诱饵的改良酵母双杂交筛选有助于确定BSTA是一种以前未知的PI3K/Akt信号调节因子。这项建议的目的是进一步了解BSTA的调节和功能，以及阻断其活动对PDAC的影响。中心假设是BSTA是致癌的Ki-Ras诱导的Akt信号的关键调节因子，并促进胰腺肿瘤的发生。基于强大的初步数据，将通过追求以下两个具体目标来检验这一假设：1)确定 KI-RAS激活Akt的机制；2)研究BSTA在体外和体内PDAC对mTOR抑制剂耐药中的作用。基于RNAi的方法和蛋白质磷酸化分析将被用来检验工作假说(目标1)，即致癌Ki-RAS通过a)通过涉及Ral小GTP酶和microRNA miR-21的机制增加BSTA的表达，以及b)在BSTA依赖的机制中刺激Akt激酶(MTORC2)和/或抑制Akt磷酸酶(PHLPP)。为了测试BSTA是否促进胰腺肿瘤的发生和耐药性(目标2)，将描绘BSTA上最小的Akt结合序列，并设计用于在PDAC细胞上测试的细胞穿透肽。在原位小鼠模型中，BSTA也将在PDAC细胞中下调，以研究肿瘤的发生和对mTOR抑制剂的耐药性。该项目的基本原理是，了解BSTA的作用和调控可能有助于确定靶向PI3K通路和致癌Ki-RAS信号的新方法，从而有效治疗PDAC。这一贡献意义重大，因为它有望帮助揭示K-RasG12D额外控制Akt的新机制的细节，并导致针对胰腺导管癌PI3K/Akt通路的替代药物策略的开发。这项研究方案具有创新性，因为它描述了致癌的Ki-Ras和Akt之间的一种新的机制联系，一旦正确描述，将提供一种与目前可用的靶向PI3K/Akt途径的新的、本质上不同的方法。总之，这些研究有望从根本上促进对Ki-RAS和PI3K/Akt信号的理解，并发现治疗胰腺导管癌的新分子靶点。