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

项目总结 胰腺导管腺癌(PDAC)患者的5年存活率约为5%，并保持在 在过去的25年里基本没有变化。当务之急是，这种癌症背后的机制 快速识别和研究，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，以及其他良好的基因突变，信号机制被解除了调控。 胰腺癌发生的已有特征仍不完全清楚。长期目标是 阐明磷脂酰肌醇3-激酶(PI3K)信号通路及其蛋白Ki-2的作用和调节 Nase介导物Akt在PDAC中的作用，并开发更有效的拮抗剂用于癌症预防和治疗 比目前可用的治疗方法更多。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是一种以前未知的PI3K/Akt信号调节因子。这项提议的目的是 目的是进一步了解BSTA的调节和功能以及阻断其活性对PDAC的影响。这个 中心假说是BSTA是KI-RAS诱导的Akt信号的关键调节者，并促进 胰腺肿瘤的发生。基于强大的初步数据，这一假设将通过追求以下结论来检验： 明确两个具体目标：1)确定KI-RAS激活Akt的机制并描绘氨基 BSTA-Akt相互作用所必需的BSTA的酸序列；2)鉴定BSTA在胰腺中的功能 肿瘤发生学。一种基于RNAi的方法，以及与GST下拉试验相结合的定点突变， 将被用来检验工作假说(目标1)，即致癌的Ki-Ras及其效应器之一激活Akt 通过增加BSTA的表达。一种仿照最小Akt结合序列的细胞通透性多肽 还将合成BSTA序列，以评估其对Akt活性和功能的影响。以检测是否致癌 Ki-RAS通过BSTA过表达和Akt信号通路(AIM)促进胰腺肿瘤的发生 2)，BSTA在原位PDAC和肝移植(转移)裸鼠动物模型中表达下调。 BSTA-siRNA-DOPC偶联物的ELS。提议的项目的基本原理是理解 而对BSTA的调控可能有助于发现靶向PI3K通路和致癌Ki-Ras信号的新途径。 为PDAC的有效治疗而努力。这一贡献意义重大，因为预计它将有助于揭示 K-RasG12D通过一种新的机制额外控制Akt并导致 靶向PI3K/Akt通路治疗胰腺癌的替代药理学策略。再一次- 搜索方案是创新的，因为它描述了致癌Ki-Ras和致癌Ki-Ras之间的新机制联系 AKT，一旦正确描述，将提供一种新的、本质上不同的方法来瞄准 PI3K/Akt途径比目前可用的。总之，这些研究预计将在#年产生积极影响。 从根本上提高对Ki-RAS和PI3K/Akt信号转导的认识，发现新的分子TAR。 用于治疗胰腺导管癌的药物。

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.