TUMOR UPTAKE OF GA67 BY PHOTODEGRADED NIFEDIPINE

光降解硝苯地平对 GA67 的肿瘤摄取

• 批准号: 6350291
• 负责人: Kathryn Ann Morton
• 金额: $ 0.81万
• 依托单位: WAKE FOREST UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-02-12 至 2001-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6350291
• 关键词: athymic mouse; biological transport; calcium channel; fluorescence spectrometry; gallium; gas chromatography mass spectrometry; high performance liquid chromatography; laboratory mouse; neoplasm /cancer radionuclide diagnosis; neoplasm /cancer transplantation; nifedipine; nitric oxide; nuclear magnetic resonance spectroscopy; photoactivation; radionuclides; radiopharmacology; tissue /cell culture; transferrin receptor; ultraviolet spectrometry

Whether Ga-67 accumulates in tumors by transferrin (Tf-dependent or independent methods has been a topic of controversy for years. Our preliminary data suggests that accumulation of Ga by most normal tissues and organs requires the presence of Tf and the transferric receptor (TfR), but that Ga uptake by tumors may be, in many cases, a Tf-independent process. Further, we have demonstrated that the Tf-independent uptake of gallium by tumor cells in-vitro can be increased significantly by a number of manipulations, the most powerful of which is incubation of the cells with nifedipine, a calcium channel blocker, that has been pre-exposed to either fluorescent or UV light. In this grant application, we will explore the mechanism and utility of photo-degraded nifedipine (PDN) in mediating Ga-67 uptake. We will determine which of the photodegradation products of nifedipine are responsible for the action on Ga-67 uptake. We will isolate the products of UV and fluorescent photo-irradiation of nifedpine chromatographically. We will characterize their physical properties by HPLC, NMR, gas chromatography-mass spectroscopy, and UV and fluorescence spectroscopy. We will assess the activity of the most abundant isolates on mediating uptake of Ga-67 in cells. For those derivatives that prove most abundant and active in promoting uptake, we will compare and define their stabilty and continued activity in promoting Ga-67 uptake under conditions of extended exposure to light and to a variety of conditions encountered in storage. With the most active, abundant and stable derivatives, we propose to define the mechanism by which PDN promotes Ga-67 uptake. Based on other reports of PDN activities, and our own observations, we will focus on the 4 most-likely ways that PDN may mediate Ga-67 uptake: (1) by means of a calcium channel; (2) by activating of a Ca2+-mediated calcium channel; (3) by an effect of nitric oxide production; or (4) by an effect related to a receptor-mediated function. We will also determine whether PDN has other biological or physiological properties that might expand their utility or complicate their clinical use. The toxicity of PDN will be assessed. The effect of these agents on the distribution of Ga-67 in normal tissues in mice will be determined, and whether the agents allow earlier imaging with less activity. The effect of nifedipine and PDN on the uptake of Ga-67 by a variety of types of tumors grown as explants of cultured cells in mice will be evaluated. This will enable us to assess whether PDN mediates uptake of Ga-67 in all tissues, or only in cancer. By comparing the magnitude of uptake in tumors of varying types, we can assess how broadly applicable PDN may be for enhancing uptake of Ga-67 in tumors. Even if the stimulatory effect on Ga-67 uptake proves not specific to tumors, but is found in all tissues, PDN may nonetheless prove useful in shortening the time required from injection of Ga-67 to imaging, and may allow diagnostic images to be obtained at a lower dose of the radionuclide.

Ga-67是否通过转铁蛋白(Tf依赖或独立的方法)在肿瘤中蓄积，多年来一直是一个有争议的话题。我们的初步数据表明，大多数正常组织和器官对镓的积累需要转铁蛋白和转铁蛋白受体(TFR)的存在，但在许多情况下，肿瘤对镓的摄取可能是一个不依赖转铁蛋白的过程。此外，我们已经证明，肿瘤细胞对镓的非转铁蛋白依赖性摄取可以通过多种操作显著增加，其中最有效的操作是将细胞与预先暴露于荧光或紫外光下的钙通道阻滞剂硝苯地平孵育。在这项拨款申请中，我们将探索光降解硝苯地平(PDN)在介导Ga-67摄取方面的机制和用途。我们将确定硝苯地平的哪些光解产物对Ga-67的摄取起作用。对硝苯地平的紫外光和荧光光照射产物进行层析分离。我们将通过高效液相色谱、核磁共振、气相色谱-质谱联用、紫外光谱和荧光光谱等手段对其物理性质进行表征。我们将评估最丰富的菌株在介导细胞对Ga-67摄取方面的活性。对于那些被证明在促进吸收方面最丰富和最活跃的衍生物，我们将比较和确定它们在延长光照条件下和在储存中遇到的各种条件下促进Ga-67吸收的稳定性和持续活性。利用最活跃、最丰富和最稳定的衍生物，我们建议定义PDN促进Ga-67摄取的机制。基于对PDN活性的其他报道，以及我们自己的观察，我们将重点讨论PDN最有可能通过的4种途径：(1)通过钙通道；(2)通过激活钙离子介导的钙通道；(3)通过一氧化氮的产生；(4)通过与受体介导的功能有关的效应。我们还将确定PDN是否具有其他生物学或生理特性，可能会扩大其用途或使其临床应用复杂化。将对PDN的毒性进行评估。这些试剂对小鼠正常组织中Ga-67分布的影响将被确定，以及这些试剂是否允许在较低活性的情况下进行早期成像。将评估硝苯地平和PDN对作为培养细胞外植体生长的各种类型的肿瘤摄取Ga-67的影响。这将使我们能够评估PDN是否在所有组织中介导Ga-67的摄取，或者仅在癌症中。通过比较不同类型肿瘤的摄取程度，我们可以评估PDN在增强肿瘤对Ga-67摄取方面的广泛应用程度。即使对Ga-67摄取的刺激作用被证明不是肿瘤特有的，而是在所有组织中发现的，PDN仍可能被证明在缩短从注射Ga-67到成像所需的时间方面是有用的，并可能允许以较低剂量的放射性核素获得诊断图像。