A Drosophila model for the electrophile counter-attack chemoprevention strategy

描述(申请人提供)：这项申请的长期目标是通过建立黑腹果蝇作为Keap1-Nrf2信号的遗传和药理学研究平台来加速癌症化学预防研究。初步研究结果表明，果蝇Nrf2和Keap1的同源物(分别为Cnc-C和dKeap1)包含一个细胞保护模块，该模块对氧化剂和化学预防性药物oltiraz做出反应，调节应激诱导基因，并增加果蝇对氧化应激的耐受性。该项目将表征奥替拉兹和新的合成三萜类化合物(由达特茅斯医学院Michael B.Sporn博士提供)对果蝇Nrf2(Cnc-C)信号激活的影响。功能实验将确定这些化学预防药物对果蝇的作用机制和生理效应。通过在申请人实验室开发的Nrf2或Keap1功能获得或丧失的遗传背景下进行实验，将绘制介导抗氧化反应元件激活和Nrf2靶基因表达的信号通路。生物检测将监测奥替拉兹和三萜类化合物对有机体对氧化应激源的抵抗力和寿命的影响。总之，这些实验将建立一个遗传上易于处理的系统，用于研究在完整的生物体中对Nrf2信号的药物操作的影响，该系统是对现有的啮齿动物、鱼类和基于细胞的模型系统的补充。这项工作将是果蝇遗传学力量将有助于解决关键的临床化学预防问题的起点。未来的研究将在这些初步研究完成后成为可行的，将分析Nrf2系统与体内其他应激反应和防御机制的整合，为合理设计组合靶向策略提供基础。此外，对化学预防药物在果蝇中的长期组织效果的评估可能有助于优先考虑具有提高生活质量特征的药物，以进一步进行临床前开发。最后，果蝇可能成为快速分析Nrf2激活剂的体内构效关系(SAR)的平台。

DESCRIPTION (provided by applicant): The long-term objective of this application is to accelerate cancer chemoprevention research by establishing Drosophila melanogaster as a platform for the genetic and pharmacological study of Keap1-Nrf2 signaling. Preliminary findings suggest that the Drosophila homologues of Nrf2 and Keap1 (CNC-C and dKeap1, respectively) comprise a cell protective module that responds to oxidants and to the chemopreventive agent oltipraz, regulates stress-inducible genes, and confers increased tolerance of the fly to oxidative stress. This project will characterize the effects of oltipraz and of the new synthetic triterpenoids (provided by Dr Michael B. Sporn, Dartmouth Medical School) on the activation of Drosophila Nrf2 (CNC-C) signaling. Functional experiments will determine the mechanisms of action and physiological effects of these chemopreventive drugs in Drosophila. By conducting experiments in genetic backgrounds of gain- or loss-of-function for Nrf2 or Keap1 that have been developed in the laboratory of the applicant, the signaling pathway mediating the activation of the Anti-oxidant Response Element and the expression of Nrf2 target genes will be charted. Biological assays will monitor the effects of oltipraz and triterpenoids on the organism's resistance to oxidative stressors and on its lifespan. Together, these experiments will establish a genetically tractable system for studying the effects of pharmacological manipulation of Nrf2 signaling in an intact organism that is complementary to existing rodent, fish, and cell-based model systems. This work will be the starting point from which the power of Drosophila genetics will help to address crucial clinical issues of chemoprevention. Future research that will become feasible upon completion of these pilot studies will analyze the integration of the Nrf2 system with other mechanisms of stress response and defense in vivo, providing a basis for rational design of combinatorial targeting strategies. Furthermore, the evaluation of long-term organismal effects of chemopreventive agents in Drosophila could help prioritize drugs with quality-of-life promoting profiles for further preclinical development. Finally, Drosophila could become a platform for rapid in vivo structure-activity relationship (SAR) analyses of Nrf2 activators.