PET & MR QUANTITATIVE IMAGING OF TRANSGENE EXPRESSION

宠物

• 批准号: 6377484
• 负责人: Juri George Gelovani
• 金额: $ 38.46万
• 依托单位: SLOAN-KETTERING INST CAN RESEARCH
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-05-01 至 2003-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6377484
• 关键词: aminohydrolases; bioimaging /biomedical imaging; combination cancer therapy; diagnosis design /evaluation; drug metabolism; fluorouracil; fusion gene; gene expression; gene therapy; laboratory rat; neoplasm /cancer chemotherapy; neoplasm /cancer diagnosis; nonhuman therapy evaluation; noninvasive diagnosis; nuclear magnetic resonance spectroscopy; phosphotransferases; positron emission tomography; prodrugs; prognosis; reporter genes; tissue /cell culture; transfection

Non-invasive imaging of cytosine deaminase (CD) gene expression in clinical cancer gene therapy trials with CD plus 5FC combination therapy would be of considerable value. It would allow us to monitor the location, magnitude, and persistence of CD gene expression over time. It would also allow us to assess whether the level of CD gene expression is adequate with respect to producing sufficient levels of 5FC metabolites, which are toxic to the tumor tissue and can produce a good therapeutic response. Previous attempts by other researchers to obtain images and measures of CD gene expression with positron emission tomography (PET) and radiolabeled [18F]5FC in tumors that express CD have failed. This is because [18F]5FU, which is produced by the CD enzyme from [18F]5FC, freely diffuses out of the CD-expressing tumor cells and does not concentrate within these cells. We propose to develop and validate a novel hybrid "reporter" gene that combines two pro-drug activating genes, cytosine deaminase (CD) and uracil phosphoribo-transferase (UPRT). The UPRT gene would act as both a reporter gene for CD and as a therapeutic gene by potential CD plus 5FC pro-drug activation therapy. The combined action of the CD and UPRT enzymes should allow PET imaging with activation therapy. The combined action of the CD and UPRT enzymes should allow PET imaging with [18F]5FC and magnetic resonance spectroscopy (MRS) imaging with non-radiolabeled 5FC. Namely, CD converts [18F]5FC into [18F]5FU, and UPRT converts it into [18F]5FU-monophospate ([18F]FUMP), which is "trapped", within the transduced cell and accumulates to a high levels. The high levels of [18F]5FUMP and cold 5FUMP can be imaged with PET and MRS, respectively. The rate of UPRT-catalyzed conversion of [18f]5fu INTO [18F]5FUMP is significantly faster than the rate of CD-catalyzed conversion of [18F]FC to [18F]5FC to [18F]5FU. CD-mediated catalysis is the rate-limiting step in accumulation of [18F]FUMP in transduced cells. Therefore, images of [18F]5FUMP accumulation would reflect CD expression in transduced tumors. This proposal represents a new approach that allows multi-modality imaging and monitoring of treatment efficacy in CD plus 5FC pro-drug activation gene therapy of cancer. The results of studies in tissue cultures and in experimental animal tumors will be immediately applicable to ongoing gene therapy trials involving the CD and/or UPRT genes. This approach will provide clinicians with a choice of two imaging modalities for detection of gene expression and for monitoring responses to gene therapy. Namely, PET and/or MRS imaging could be used separately or in combination.

在临床癌症基因治疗试验中，胞质脱氨酶（CD）基因表达的非侵入性成像具有CD Plus 5FC组合疗法的非侵入性成像。这将使我们能够随着时间的推移监视CD基因表达的位置，大小和持久性。它还使我们能够评估CD基因表达的水平是否足以产生足够水平的5FC代谢产物，这些5FC代谢物对肿瘤组织有毒并可以产生良好的治疗反应。其他研究人员先前尝试通过正电子发射断层扫描（PET）获得CD基因表达的图像和度量，并在表达CD的肿瘤中进行放射性标记[18F] 5FC。这是因为[18F] 5FU是由[18F] 5FC的CD酶产生的，它可以自由地从表达CD的肿瘤细胞中扩散出来，并且不会集中在这些细胞中。我们建议开发和验证一种新型的混合“报告基因”基因，该基因结合了两个促毒激活基因，胞质脱氨酶（CD）和尿嘧啶磷酸磷脂转移酶（UPRT）。 UPRT基因既可以作为CD的报告基因，又是潜在的CD加5FC Pro-Pro-Pro-Pro-Pro-Pro-Pro-Pro-Pro-Pro-Pro-Pro-Pro-drug激活疗法的基因。 CD和UPRT酶的联合作用应允许使用激活疗法进行PET成像。 CD和UPRT酶的组合作用应允许使用[18F] 5FC和磁共振光谱（MRS）成像进行宠物成像，并使用非二醇标记的5FC进行成像。也就是说，CD将[18F] 5FC转换为[18F] 5FU，UPRT将其转换为[18F] 5FU单噬物孢地（[[18F] Fump），该（[18F] fump）被“捕获”，在传递的细胞内，并积聚到高水平。高水平的[18F] 5 fump和冷5 fump可以分别用宠物和MRS成像。 [18F] 5FU到[18F] 5FUMP的UPRT催化转化率明显快于[18F] FC对[18F] 5FC至[18F] 5FU的CD催化转化率。 CD介导的催化是转导细胞中[18F] Fump积累的速率限制步骤。因此，[18F] 5 fump积累的图像将反映在转导的肿瘤中的CD表达。该提案代表了一种新方法，该方法允许多模式成像并监测CD Plus 5FC Pro-Pro-Pro-Pro-Pro-Pro-Pro-Pro-Pro-Pro-Pro-Pro-Pro-Pro-drug激活基因治疗。组织培养和实验性动物肿瘤的研究结果将立即适用于涉及CD和/或UPRT基因的持续基因治疗试验。这种方法将为临床医生提供两种成像方式，用于检测基因表达和监测对基因治疗的反应。也就是说，宠物和/或MRS成像可以单独使用或组合使用。