TUMOR UPTAKE OF GA67 BY PHOTODEGRADED NIFEDIPINE

光降解硝苯地平对 GA67 的肿瘤摄取

• 批准号: 6500947
• 负责人: Kathryn Ann Morton
• 金额: $ 25.96万
• 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 2002-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6500947
• 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是通过转铁蛋白（tf依赖的还是独立的方法）在肿瘤中积累，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的Ga积累需要Tf和转移受体（TfR）的存在，但在许多情况下，肿瘤对Ga的摄取可能是一个与Tf无关的过程。此外，我们已经证明，体外肿瘤细胞对镓的tf非依赖性摄取可以通过多种操作显着增加，其中最有效的是用硝苯地平（一种钙通道阻滞剂）对细胞进行孵卵，该细胞已预先暴露于荧光或紫外线下。在这项拨款申请中，我们将探索光降解硝苯地平（PDN）介导Ga-67摄取的机制和用途。我们将确定硝苯地平的哪一种光降解产物对Ga-67的吸收起作用。对硝苯地平的紫外和荧光光照射产物进行色谱分离。我们将通过高效液相色谱，核磁共振，气相色谱-质谱，紫外和荧光光谱来表征它们的物理性质。我们将评估最丰富的分离物在细胞中介导Ga-67摄取的活性。对于那些证明在促进吸收方面最丰富和最活跃的衍生物，我们将比较和定义它们在长时间暴露于光和各种储存条件下促进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。基于其他关于PDN活性的报道和我们自己的观察，我们将重点关注PDN介导Ga-67摄取的4种最可能的方式：(1)通过钙通道；(2)通过激活Ca2+介导的钙通道；(3)受一氧化氮生成的影响；或(4)与受体介导的功能相关的效应。我们还将确定PDN是否具有其他生物学或生理学特性，这些特性可能会扩大其效用或使其临床应用复杂化。将评估PDN的毒性。这些药物对小鼠正常组织中Ga-67分布的影响将被确定，以及这些药物是否允许活性较低的早期成像。硝苯地平和PDN对不同类型肿瘤对Ga-67摄取的影响将被评估为小鼠培养细胞的外植体。这将使我们能够评估PDN是在所有组织中介导Ga-67的摄取，还是仅在癌症中。通过比较不同类型肿瘤对Ga-67的摄取程度，我们可以评估PDN在促进肿瘤对Ga-67摄取方面的广泛应用。即使对Ga-67摄取的刺激作用不是肿瘤特异性的，而是在所有组织中发现的，PDN仍然可能证明在缩短从注射Ga-67到成像所需的时间方面是有用的，并且可能允许在较低剂量的放射性核素下获得诊断图像。