Pharmacologic /Genetic Inhibition of XBP1 as Hypoxia Targeted Therapeutic Strateg

XBP1 的药理学/基因抑制作为缺氧靶向治疗策略

• 批准号: 7196188
• 负责人: ALBERT KOONG
• 金额: $ 25.48万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-12-01 至 2012-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7196188
• 关键词: Antineoplastic Agents; Binding Proteins; Biochemical; Biological Assay; Boxing; Cell Line; Cells; Dimerization; Dominant-Negative Mutation; Endoplasmic Reticulum; Gene Targeting; Genetic; Growth; Hypoxia; Image; Integral Membrane Protein; Lethal Dose 50; Link; Luciferases; Malignant neoplasm of pancreas; Mediating; Methods; Modeling; Monitor; Northern Blotting; Nude Mice; Phosphotransferases; Proteins; RNA Splicing; Reporter; Reverse Transcriptase Polymerase Chain Reaction; Role; Signal Pathway; Specificity; Stress; Tetracycline; Tetracyclines; Therapeutic; Transfection; Tumor Cell Invasion; base; chemotherapy; endonuclease; gemcitabine; high throughput screening; in vivo; inhibitor/antagonist; matrigel; neoplastic cell; pancreatic neoplasm; research study; response; small hairpin RNA; small molecule libraries; subcutaneous; therapeutic target; transcription factor; tumor; tumor growth

Hypoxic and endoplasmic reticulum (ER) stress are two essential components of the tumor microenvironment linking the cellular response to these factors with tumor growth. We have previously shown that hypoxia activates the unfolded protein response (DPR), a signaling pathway that is triggered in response to ER stress. X-box binding protein (XBP-1) is an important regulator of the transcriptional branch of this response and is spliced into its active for by IRE1, an ER transmembrane protein. Using XBP-1 deficient cells, we demonstrated that XBP-1 mediates survival under hypoxia and is critical for tumor growth. Given its role in regulating survival under hypoxia and its requirement for tumor growth, we hypothesize that targeting XBP-1 will be an effective therapeutic strategy. However, there are few examples of anti-cancer drugs that can effectively inhibit transcription factor activation. Therefore, our strategy for inhibiting XBP-1 is to block the activity of IRE1, an ER transmembrane protein responsible for splicing XBP-1 into its active form. IRE1 is activated by dimerization and autophosphorylation through its kinase domain. The endonuclease activity of IRE1 depends upon having an intact kinase domain, and to date, XBP-1 is the only described substrate for the endonuclease function of IRE1. In this proposal, we will investigate the effects of inhibiting XBP-1 using a pharmacologic and genetic strategy. We have identified a group of XBP-1 inhibitors (termed irestatins) in a high throughput screen of a 66,000 compound small molecule library. We have also generated several cell lines in which we inhibit XBP- 1 using dominant negative inhibitors of IRE and XBP-1 as well as a tetracycline regulated XBP-1 shRNA expressing cell line. We will monitor in vivo XBP-1 splicing activity within tumors using bioluminescent imaging of a luciferase reporter regulated by XBP-1 splicing. We will examine the effects of XBP-1 inhibition by multiple methods in a using a subcutaneous and orthotopic model of pancreatic cancer. We will use biochemical cell based assays to define the mechanism of action of the irestatins, investigate the consequences of XBP-1 inhibition on pancreatic tumor growth, and combine XBP-1 inhibition with other promising therapies for pancreatic cancer.

缺氧和内质网应激是肿瘤的两个重要组成部分