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: 8612063
• 负责人: Sushovan Guha
• 金额: $ 16.39万
• 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 2014-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8612063
• 关键词: Ki; Ras; Signaling; Pancreatic; Cancer

PROJECT SUMMARY 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 delineate the amino acid sequence of BSTA that is essential for BSTA-Akt interaction; and 2) Identify BSTA function in pancreatic tumorigenesis. An RNAi-based approach, and site-directed mutagenesis coupled to GST pull-down assays, will be used to test the working hypothesis (Aim 1) that oncogenic Ki-Ras and one of its effectors activate Akt by increasing BSTA expression. A cell-permeable peptide patterned after the minimal Akt-binding sequence of BSTA sequence will also be synthesized to evaluate its effects on Akt activity and function. To test if oncogenic Ki-Ras promotes pancreatic tumorigenesis through BSTA overexpression and the Akt signaling pathway (Aim 2), BSTA will be downregulated in orthotopic PDAC and liver colonization (metastatic) nude mice animal mod- els with BSTA-siRNA-DOPC conjugate. 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 signal- ing 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 pancreatic ductal cancer. The re- search 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 tar- gets for the treatment of pancreatic ductal cancer.

项目摘要 胰腺导管腺癌（PDAC）患者的5年生存率约为5%， 在过去的25年里基本没有变化。当务之急是，这种癌症的基础机制， 快速识别和研究，以便开发新的分子疗法。这其中大部分都 信号传导机制在Ki-Ras基因的遗传改变中失调， 胰腺癌发生的既定标志，仍不完全清楚。长期目标是 阐明磷脂酰肌醇3-激酶（PI 3 K）信号通路及其蛋白ki-1的作用和调节。 PDAC中的nase介导剂Akt，并开发针对它们的更有效的拮抗剂用于癌症预防， 比目前可用的治疗。为了追求这一目标，以Akt为诱饵的改良酵母双杂交筛选 帮助确定BSTA作为PI 3 K/Akt信号传导的先前未知的介质。本提案的目的 进一步了解BSTA的调节和功能以及阻断其活性对PDAC的影响。的 中心假设是BSTA是致癌Ki-Ras诱导的Akt信号传导的关键调节剂，并促进Akt信号传导。 胰腺肿瘤发生基于强有力的初步数据，这一假设将通过以下方式进行检验： 本研究的目的有两个：1）明确Ki-Ras激活Akt的机制，并阐明Ki-Ras在Akt中的作用机制。 BSTA-Akt相互作用所必需的BSTA的酸性序列;和2）鉴定BSTA在胰腺癌中的功能。 肿瘤发生一种基于RNAi的方法，以及与GST下拉测定偶联的定点诱变， 将用于检验致癌Ki-Ras及其效应物之一激活Akt的工作假设（目的1 通过增加BSTA表达。一种细胞渗透性肽，其模式为最小Akt结合序列， 还将合成BSTA序列以评估其对Akt活性和功能的影响。检测是否致癌 Ki-Ras通过BSTA过表达和Akt信号通路促进胰腺肿瘤发生（Aim 2），BSTA将在原位PDAC和肝定植（转移性）裸鼠动物模型中下调。 具有BSTA-siRNA-DOPC缀合物的细胞。拟议项目的基本原理是， BSTA的调节可能有助于确定靶向PI 3 K通路和致癌Ki-Ras信号的新方法- 有效治疗PDAC。这一贡献意义重大，因为它有望帮助揭示 K-RasG 12 D另外控制Akt并导致 靶向胰腺导管癌中PI 3 K/Akt通路的替代药理学策略。再- 这项研究是创新性的，因为它描述了致癌Ki-Ras和 Akt一旦被正确界定，将提供一种新的和实质上不同的方法来瞄准 PI 3 K/Akt通路比目前可用的。这些研究预计将产生积极影响， 从根本上推进对Ki-Ras和PI 3 K/Akt信号传导的理解，并发现新的分子靶点， 用于治疗胰腺导管癌。