Radiolabeled Probes for Imaging Caspase 3 Activation

用于 Caspase 3 激活成像的放射性标记探针

• 批准号: 6965490
• 负责人: ROBERT H MACH
• 金额: $ 30.2万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-30 至 2009-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6965490
• 关键词: apoptosis; autoradiography; bioimaging /biomedical imaging; biological models; biotechnology; carbon; chemical synthesis; cysteine endopeptidases; enzyme activity; fluorine; immunocytochemistry; laboratory mouse; laboratory rat; molecular /cellular imaging; molecular probes; pharmacokinetics; positron emission tomography; radionuclides; radiotracer; septicemia; technology /technique development

DESCRIPTION (provided by applicant): Apoptosis or Programmed Cell Death is an important biological process that is required to maintain the integrity and homeostasis of multi-cellular organisms. Apoptosis is initiated by extracellular or intracellular signals in which a complex machinery is activated to start a cascade of events that ultimately leads to the degradation of nuclear DNA and a dismantling of the cell. Apoptosis is a tightly regulated and conserved mode of cell death that does not result in injury to adjacent cells. However, necrosis is a catastrophic, unregulated mode of cell death that is characterized by an invasion of inflammatory cells and injury to adjacent tissue. Abnormal or unregulated apoptosis is believed to occur in a variety of disease states, including ischemia-reperfusion injury (i.e., myocardial infarction and stroke), neuro-degeneration (Parkinson's Disease, Alzheimer's Disease, and ALS), sepsis, and diabetic cardiomyopathy. On the other hand, the inability of a cell to undergo apoptosis is believed to play a major role in the resistance of tumor cells toward radiation, chemotherapy, and immunotherapy. Therefore, the development of a non-invasive imaging procedure that can measure apoptosis is of importance to many institutes within the National Institutes of Health. The current method for imaging apoptosis uses radiolabeled analogs of Annexin V. Annexin V is a protein that binds with high affinity to phosphatidyl serine residues that are exposed as part of membrane inversion that occurs during apoptosis. However, since membrane inversion also occurs during necrosis, imaging studies using radio-labeled Annexin V measure both apoptosis and necrosis. An alternative strategy for measuring apoptosis is to determine the level of caspase-3 activity in the cell. Caspase-3 is an "executioner" caspase and is released from an inactive zymogen (procaspase-3) late in the process of apoptosis. Furthermore, evidence suggests that inhibitors of caspase-3 may provide an effective method for preventing cellular death that occurs in diseases characterized by an increase in apoptosis (i.e., ischemia-reperfusion injury, neuro-degeneration). Therefore, a noninvasive imaging procedure that can quantify caspase-3 activity would be useful in the study of apoptosis in a wide variety of clinical conditions. However, one of the complications of imaging apoptosis is that the amount of cells undergoing apoptosis at any given time may represent only a small fraction of the total cells in an intact organ. The goal of this research project is to develop PET imaging agents possessing a high affinity and selectivity for caspase-3. The design of the imaging agents is based on a novel class of caspase 3 inhibitors developed in our laboratory, termed the Isatin Michael Acceptors or IMAs. These compounds are expected to bind irreversibly to activate caspase 3 in cells undergoing apoptosis. The irreversible binding property of the IMAs is expected to provide a high signal: noise ratio and provide a sensitive method for imaging cells undergoing apoptosis that would be of tremendous value to the PET research community.

描述（由申请人提供）： 凋亡或程序性细胞死亡是维持多细胞生物的完整性和稳态所需的重要生物学过程。凋亡是由细胞外或细胞内信号引发的，在这些信号中，激活复杂的机器以启动一系列事件，最终导致核DNA降解并拆除细胞。细胞凋亡是一种严格调节和保守的细胞死亡方式，不会导致相邻细胞受伤。然而，坏死是一种灾难性的，不受管制的细胞死亡方式，其特征是侵袭炎症细胞和对相邻组织的损伤。据信异常或不管制的凋亡发生在多种疾病状态中，包括缺血 - 灌注损伤（即心肌梗死和中风），神经脱生（帕金森氏病，阿尔茨海默氏病，阿尔茨海默氏病和ALS和ALS），sepsis和Diabeticastimomyopathy。另一方面，据信细胞无法进行细胞凋亡的能力在肿瘤细胞对放射线，化学疗法和免疫疗法的耐药性中起主要作用。因此，对可以测量细胞凋亡的非侵入性成像程序的开发对于美国国立卫生研究院内的许多研究所都很重要。 当前的成像凋亡方法使用膜联蛋白V的放射性标记类似物。膜联蛋白V是一种蛋白质，与磷脂酰丝氨酸丝氨酸残基相结合，该蛋白是在凋亡过程中发生的膜反转的一部分。然而，由于膜反转也发生在坏死期间，因此使用射量标记的膜联蛋白V进行成像研究测量凋亡和坏死。 测量凋亡的另一种策略是确定细胞中caspase-3活性的水平。 caspase-3是一种“执行者” caspase，在凋亡过程后期从非活性酶原（procaspase-3）中释放出来。 此外，有证据表明，caspase-3的抑制剂可能会提供一种有效的方法来预防细胞死亡，而细胞死亡的发生在以凋亡增加为特征的疾病中（即缺血 - 再灌注损伤，神经脱位）。因此，可以量化caspase-3活性的非侵入性成像程序将在多种临床条件下研究凋亡。但是，成像凋亡的并发症之一是在任何给定时间经历凋亡的细胞量可能仅占完整器官中总细胞的一小部分。 该研究项目的目的是开发具有高亲和力和caspase-3选择性的宠物成像剂。成像剂的设计基于在我们的实验室中开发的新型caspase 3抑制剂，称为Isatin Michael受体或IMA。预计这些化合物将不可逆转地结合以激活凋亡的细胞中的caspase 3。 IMA的不可逆转的结合特性有望提供高信号：噪声比，并为对凋亡的细胞进行成像的敏感方法，这对PET研究社区具有巨大的价值。