IMAGING COX-2 GENE EXPRESSION IN INFLAMMATION AND TUMORS

炎症和肿瘤中 COX-2 基因表达的成像

• 批准号: 6692602
• 负责人: Harvey R. Herschman
• 金额: $ 34.74万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-12-17 至 2005-09-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6692602
• 关键词: bioimaging /biomedical imaging; biomarker; carcinogenesis; cutaneous papilloma; disease /disorder model; dopamine receptor; embryonic stem cell; fluorine; ganciclovir; gene expression; gene targeting; genetically modified animals; herpes simplex virus 1; image processing; inflammation; intestine neoplasm; laboratory mouse; neoplasm /cancer genetics; neoplastic process; positron emission tomography; prostaglandin endoperoxide synthase; prostaglandins; radionuclides; reporter genes; transfection /expression vector

Prostaglandins modulate platelet aggregation, kidney function, immune responses, respiratory function, reproduction and other physiological processes. Abnormalities of prostaglandin biosynthesis occur in pain, fever, bone resorption, cardiovascular disease, inflammation and cancer. Cyclooxygenase/prostaglandin synthase (COX/PGS) catalyzes the synthesis of the common intermediate, PGH2, in the production of prostaglandins. We identified a second, inducible COX, COX-2. We also demonstrated that COX-2 induction is required for prostaglandin production in response to growth factors and inflammatory stimuli, a result that provides the rationale for the clinical utility of COX-2 specific inhibitors. Elevated COX-2 gene expression plays a role in many pathologies. The ability to measure COX-2 expression in living animals would permit us to (i) determine the role of COX-2 in inflammatory responses and tumor progression and (ii) evaluate the utility of monitoring COX-2 expression as an intermediary marker of both disease and therapeutic response. We developed methods to measure reporter gene expression repetitively, non-invasively and quantitatively in living animals. We express reporter genes whose protein products sequester positron-labeled probes, then detect reporter gene-dependent probe retention by using positron emission tomography (PET). We have developed two systems; (i) Herpes Simplex Virus 1 thymidine kinase (HSV1-tk) as the "PET reporter gene" and [18F]-8-acycloguanosines (ganciclovir, penciclovir) as the "PET reporter probes", and (ii) the dopamine D2 receptor (D2R) as the PET reporter gene and [18F] fluoroethylspiperone as the PET reporter probe. We validated these two PET reporter gene systems in both a somatic viral delivery model and in transplantable tumor models. We will develop procedures to quantitatively and non-invasively monitor PET reporter gene expression from COX-2 promoter-driven transgenes and from the endogenous COX-2 gene. We will create transgenic and "knock-in" mice in which the HSV1-tk and D2R PET reporter probes to monitor COX-2 gene expression in four inflammation models (the carageenan-injected paw, air-pouch inflammation and liver inflammation) and in two tumor induction systems [multi-stage initiation-promotion- progression skin carcinogenesis and intestinal neoplasia in min1(+/- )mice]. These mice will permit investigators to monitor COX-2 expression in a variety of paradigms.

前列腺素调节血小板聚集、肾功能、免疫反应、呼吸功能、生殖等生理过程。前列腺素生物合成异常见于疼痛、发热、骨吸收、心血管疾病、炎症和癌症。环氧合酶/前列腺素合成酶（COX/PGS）在前列腺素的生成过程中催化常见中间体PGH2的合成。我们鉴定出第二种诱导型COX COX-2。我们还证明，在对生长因子和炎症刺激的反应中，前列腺素的产生需要COX-2诱导，这一结果为COX-2特异性抑制剂的临床应用提供了基本原理。COX-2基因表达升高在许多疾病中起作用。在活体动物中测量COX-2表达的能力将使我们能够(i)确定COX-2在炎症反应和肿瘤进展中的作用，（ii）评估监测COX-2表达作为疾病和治疗反应的中间标记的效用。我们开发了在活体动物中重复、无创和定量测量报告基因表达的方法。我们表达报告基因，其蛋白产物与正电子标记的探针隔离，然后通过正电子发射断层扫描（PET）检测报告基因依赖的探针保留。我们发展了两种体系；(1)单纯疱疹病毒1型胸苷激酶（HSV1-tk）作为“PET报告基因”，[18F]-8-无环鸟苷（更昔洛韦、喷昔洛韦）作为“PET报告探针”，(2)多巴胺D2受体（D2R）作为PET报告基因，[18F]氟乙基spiperone作为PET报告探针。我们在体细胞病毒传递模型和可移植肿瘤模型中验证了这两个PET报告基因系统。我们将开发程序，从COX-2启动子驱动的转基因和内源性COX-2基因中定量和无创地监测PET报告基因表达。我们将利用HSV1-tk和D2R PET报告基因探针构建转基因和敲入小鼠，在四种炎症模型（注射角叉胶的爪子、气囊炎症和肝脏炎症）和两种肿瘤诱导系统（min1（+/-）小鼠的多阶段启动-促进-进展皮肤癌和肠道肿瘤）中监测COX-2基因的表达。这些小鼠将允许研究人员在各种范式中监测COX-2的表达。