ENZYME - ACTIVATED PROTON MRI CONTRAST AGENTS

酶 - 活化质子 MRI 造影剂

• 批准号: 7956960
• 负责人: JIAN-XIN YU
• 金额: $ 0.89万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2010-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7956960
• 关键词: Adverse effects; Animals; Biological Markers; Bioluminescence; Blood Vessels; Cell Culture Techniques; Cells; Chelating Agents; Clinical Trials; Complex; Computer Retrieval of Information on Scientific Projects Database; Contrast Media; Detection; Development; Diagnosis; Disease; Early Diagnosis; Enzymes; Escherichia coli; Exhibits; Fluorescence; Funding; Galactose; Gene Expression; Generations; Genes; Glutamate Carboxypeptidase II; Glutamates; Grant; Growth; Image; Institution; LacZ Genes; Ligands; Location; Magnetic Resonance Imaging; Malignant neoplasm of prostate; Metabolism; Monitor; Motion; Mus; Necrosis; Nuclear; Oncogenes; Patients; Positron-Emission Tomography; Process; Protocols documentation; Protons; Quality of life; Rattus; Relaxation; Reporter; Reporter Genes; Research; Research Personnel; Resolution; Resources; Series; Signal Transduction; Site; Source; Surface Antigens; System; Techniques; Testing; Therapeutic; Transfection; Transgenes; Translations; United States National Institutes of Health; base; beta-Galactosidase; cancer cell; cancer gene expression; cancer therapy; clinical practice; design; enzyme activity; extracellular; gadolinium 1,4,7,10-tetraazacyclododecane-N,N' ,N' ' ,N' ' ' -tetraacetate; gene therapy; improved; in vivo; novel; novel strategies; response; single photon emission computed tomography; success; transgene expression; treatment strategy; tumor

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Gene therapy has emerged as a potentially promising strategy for treatment of prostate cancer. However, widespread implementation is hindered by difficulties in assessing the success of transfection: in particular, assessing the location, magnitude and persistence of transgene expression. Reporter genes and associated molecules should allow assessment of gene expression. lacZ gene encoding E. coli beta-galactosidase (beta-gal) has already been recognized as the most commonly used reporter system. Moreover, prostate-specific membrane antigen (PSMA), as the most well-established, highly restricted prostate cancer cell surface antigen, has been identified as an ideal antigenic target in prostate cancer. Much elegant research has been directed at developing non-therapeutic reporter genes and imaging protocols to non-invasively in vivo reveal gene expression and cancer itself, such as nuclear imaging (PET, SPECT), fluorescence, bioluminescence and new near infrared reporter molecules. MRI techniques have opened the realm of imaging at very high resolutions in small animals during development and in clinical practice. Recently, a new emerging generation of MRI contrast agents, so-called "smart" contrast agents of developing MRI tests specific for biomarkers indicative of particular disease states and aiding in the early detection and diagnosis, hold great promise in the gene therapy arena. We propose to develop a novel class of "smart" Gd3+-based MRI contrast agents for in vivo detection of beta-gal or PSMA activity. This new concept of the "smart" Gd3+-based MRI contrast agents is composed of three moieties: (A) a signal enhancement group, such as Gd-DOTA or Gd-PCTA; (B) an Fe3+ chelating group; (C) beta-D-galactose or beta-glutamate. Following cleavage by lacZ transgene or PSMA in prostate cancer cells, the released, activated aglycone Fe3+-ligand will spontaneously trap endogenous Fe3+ at the site of enzyme activity forming a highly stable complex. Significantly, this complex will exhibit restricted motion of the Gd3+ chelates enhancing relaxivity. In addition, a paramagnetic chelator based on the Fe3+ will generate strong relaxation. This process will provide contrast based on enzyme beta-gal or PSMA stimulated local accumulation. The combination of Gd3+ and Fe3+ contrast agents for in vivo detection of beta-gal or PSMA activity is fundamentally new approach for in vivo monitoring gene activity or in vivo imaging of prostate cancer. We plan to synthesize series of novel "smart" MRI contrast agnets well-designed for detecting beta-gal or PSMA activity in prostate cancer cell culture, explore the feasibility of applying the most promising analogies to cells grown in vivo in mice and rats, and compare with vascular extent and necrosis to analyse the correlation of novel "smart' MRI contrast agents response to tumor size and growth. The ultimate objective is to develop a new concept of "smart" MRI contrast agents for in vivo assessment of beta-gal or PSMA activity, thereby, to establish a novel platform for in vivo monitoring of lacZ transgene expression in prostate cancer gene therapy or in vivo imaging of the prostate cancer itself by assessing PSMA through an extracellular MRI approach. Basically, this novel concept combines all the approaches of reaching the highest possible relaxivities, and the combination of three functional moieties is based on the clinically applied strategies on cancer therapy. We believe the technique translation to clinical investigations with the high promise of in vivo monitoring gene therapy and in vivo imaging of prostate cancer will improve efficacy while reducing side effects and hence improving quality of life for patients with prostate cancer, and the technique will be of widespread utility to investigators probing other diseases.

该子项目是利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 基因治疗已经成为治疗前列腺癌的一种潜在的有前途的策略。然而，广泛的实施受到难以评估转染成功的阻碍：特别是，评估转基因表达的位置、幅度和持续性。报告基因和相关分子应允许评估基因表达。lacZ基因编码E.大肠杆菌β-半乳糖苷酶（β-gal）已经被认为是最常用的报道系统。此外，前列腺特异性膜抗原（PSMA）作为最成熟的、高度限制性的前列腺癌细胞表面抗原，已被确定为前列腺癌的理想抗原靶点。 许多优秀的研究已经针对开发非治疗性报告基因和成像方案，以非侵入性地在体内揭示基因表达和癌症本身，例如核成像（PET，SPECT），荧光，生物发光和新的近红外报告分子。MRI技术在小动物的开发和临床实践中开辟了非常高分辨率的成像领域。最近，新出现的一代MRI造影剂，即所谓的"智能"造影剂，其开发对指示特定疾病状态的生物标志物特异性的MRI测试并有助于早期检测和诊断，在基因治疗竞技场中具有很大的前景。 我们建议开发一种新型的"智能" Gd 3+为基础的MRI造影剂在体内检测β-半乳糖或PSMA的活动。这种"智能" Gd 3+基MRI造影剂的新概念由三个部分组成：（A）信号增强基团，如Gd-DOTA或Gd-PCTA;（B）Fe 3+螯合基团;（C）β-D-半乳糖或β-谷氨酸。在前列腺癌细胞中被lacZ转基因或PSMA切割后，释放的活化的糖苷配基Fe 3 +-配体将自发地在酶活性位点捕获内源性Fe 3+，形成高度稳定的复合物。值得注意的是，该复合物将表现出Gd 3+螯合物的受限运动，从而增强弛豫性。此外，基于Fe 3+的顺磁性螯合剂将产生强弛豫。该过程将提供基于酶β-gal或PSMA刺激的局部积累的对比。用于体内检测β-gal或PSMA活性的Gd 3+和Fe 3+造影剂的组合是用于体内监测基因活性或前列腺癌体内成像的基本上新的方法。 我们计划合成一系列新型"智能" MRI造影剂，这些造影剂被精心设计用于检测前列腺癌细胞培养物中的β-gal或PSMA活性，探索将最有前途的类似物应用于小鼠和大鼠体内生长的细胞的可行性，并与血管范围和坏死进行比较，以分析新型"智能" MRI造影剂对肿瘤大小和生长的反应的相关性。 最终目的是开发一种新概念的"智能" MRI造影剂，用于体内评估β-gal或PSMA活性，从而建立一种新的平台，用于在前列腺癌基因治疗中体内监测lacZ转基因表达或通过细胞外MRI方法评估PSMA对前列腺癌本身进行体内成像。基本上，这种新的概念结合了所有达到最高可能的弛豫率的方法，并且三个功能部分的组合是基于癌症治疗的临床应用策略。我们相信，将该技术转化为临床研究，并对前列腺癌的体内监测基因治疗和体内成像具有很高的前景，将提高疗效，同时减少副作用，从而提高前列腺癌患者的生活质量，该技术将对探索其他疾病的研究人员具有广泛的实用性。