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: 8362895
• 负责人: SHRIKANTH A REDDY
• 金额: $ 0.43万
• 依托单位: UNIVERSITY OF TX MD ANDERSON CAN CTR
• 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 2012-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8362895
• 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 Delivery Systems; 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. PUBLIC HEALTH RELEVANCE: Pancreatic cancer is a highly aggressive and rapidly fatal disease. The studies proposed in this grant application may be expected to fundamentally advance our understanding of Ki-Ras and PI3K/Akt signaling and uncover new molecular targets and alternative therapeutic strategies for the treatment of pancreatic ductal cancer. The proposed research is therefore relevant to public health and to the NIH mission as defined in the "Consensus Report of the NCI Clinical Trials Planning Meeting on Pancreas Cancer Treatment".

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。必须迅速确定这种癌症的机制 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标志而失调的信号传导机制仍不完全清楚。长期目标是阐明磷酸肌醇3激酶（PI3K）信号通路及其蛋白激酶介质Akt在PDAC中的作用和调节，并开发比目前可用的更有效的拮抗剂用于癌症预防和治疗。为了实现这一目标，以 Akt 作为诱饵的改良酵母双杂交筛选有助于将 BSTA 识别为以前未知的 PI3K/Akt 信号传导介质。该提案的目的是进一步了解 BSTA 的监管和功能以及阻止其活动对 PDAC 的影响。核心假设是 BSTA 是致癌 Ki-Ras 诱导的 Akt 信号传导的关键调节因子，并促进胰腺肿瘤发生。基于强有力的初步数据，该假设将通过追求以下两个具体目标来检验：1）确定 Ki-Ras 激活 Akt 的机制； 2) 体外和体内研究BSTA在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测定将用于测试工作假设（目标 1），即致癌性 Ki-Ras 通过以下方式激活 PDAC 细胞中的 Akt：a) 通过涉及 Ral 小分子的机制增加 BSTA 表达GTPases 和 microRNA miR-21，b) 在 BSTA 依赖性机制中刺激 Akt 激酶 (mTORC2) 和/或抑制 Akt 磷酸酶 (PHLPP)。为了测试 BSTA 是否促进胰腺肿瘤发生和耐药性（目标 2），将描绘 BSTA 上的最小 Akt 结合序列，并设计细胞可穿透肽以在 PDAC 细胞上进行测试。 BSTA 也将在 PDAC 细胞中下调，以研究原位小鼠模型中的肿瘤发生和对 mTOR 抑制剂的耐药性。该项目的基本原理是，了解 BSTA 的作用和调节可能有助于确定针对 PI3K 通路和致癌 Ki-Ras 信号传导的新方法，以有效治疗 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，并导致开发针对胰腺导管癌中 PI3K/Akt 通路的替代药理学策略。该研究提案具有创新性，因为它描述了致癌 Ki-Ras 和 Akt 之间的一种新颖的机制联系，一旦正确描述，它将提供一种与目前可用的靶向 PI3K/Akt 途径截然不同的新方法。总之，这些研究预计将从根本上增进对 Ki-Ras 和 PI3K/Akt 信号传导的理解并发现治疗胰腺导管癌的新分子靶点，从而产生积极影响。 公众健康相关性：胰腺癌是一种高度侵袭性且迅速致命的疾病。本次拨款申请中提出的研究有望从根本上增进我们对 Ki-Ras 和 PI3K/Akt 信号传导的理解，并发现治疗胰腺导管癌的新分子靶点和替代治疗策略。因此，拟议的研究与公共卫生和《NCI 胰腺癌治疗临床试验计划会议共识报告》中定义的 NIH 使命相关。