MEMBRANE FREE RADICALS IN PHOTODYNAMIC CANCER THERAPY

光动力学疗法是一种新兴的、有前途的肿瘤治疗方法 这是一种正在世界范围内研究的模式。 长期目标 本研究的目的是探讨其模式的基本机制 在生物化学和细胞水平的行动，因此找到方法， 增强PDT的疗效。 我们假设， 增强自由基脂质过氧化过程将导致增加 PDT的有效性。 这项建议的工作假设是， 使用血卟啉衍生物制剂的光动力疗法 由于Photofrin（PDT/HPD）在细胞膜中产生单线态氧， 肿瘤细胞膜和肿瘤血管内皮细胞膜 系统 这种单线态氧与不饱和脂质反应， 胆固醇，产生氢过氧化物，可以作为引发剂， 自由基脂质过氧化链反应，破坏膜 功能 我们相信微血管内皮细胞是一个关键 这些过氧化过程的目标。 我们进一步假设， 环境，将加强'黑暗'自由基脂质过氧化作用 光传递后的反应将导致增强的内皮细胞 细胞损伤和死亡。 内皮细胞似乎特别 对自由基介导的氧化应激敏感。 因此，在所有 实验中，我们将比较微血管 血管内皮细胞和两种肿瘤细胞 细胞系 L1210小鼠白血病和MCF-7人乳腺癌。 本项目的工作假设将通过以下方式进行检验 具体目标： I. 确定是否促氧化剂，如铁，或抗坏血酸，或铁与 抗坏血酸，将增强PDT/HPD对细胞的光毒性， 相反，确定小分子抗氧化剂，如维生素E， Lazaroids和BHT将提供抗过氧化保护 光毒性 二. 确定膜源性自由基是否完整产生， 功能细胞的PDT/HPD，如果促氧化剂将提高自由 自由基过氧化过程，然后确定是否产生自由基 与光毒性有关。 三.确定是否增加细胞膜的氧化性， 多不饱和脂肪酸的比例会增加光毒性 PDT/HPD 四. 我们将利用分子生物学技术对抗氧化剂进行修饰 酶谱的细胞，并确定这是否会改变他们的 PDT/HPD敏感性。 诉 详细研究可能是关键的基本化学反应 PDT/HPD光毒性。

Photodynamic therapy (PDT) is a new and promising cancer treatment modality that is being investigated worldwide. The long term objective of this research is to investigate the fundamental mechanisms of its mode of action at the biochemical and cellular level and hence find ways to enhance the efficacy of PDT. We hypothesize that an environment that enhances free radical lipid peroxidation processes will lead to increased effectiveness of PDT. The working hypothesis of this proposal is that photodynamic therapy with a hematoporphyrin derivative preparation such as Photofrin (PDT/HPD) produces singlet oxygen in cell membranes, both tumor cell membranes and endothelial cell membranes of the tumor vascular system. This singlet oxygen reacts with unsaturated lipids and cholesterol, yielding hydroperoxides, which can serve as initiators of free radical lipid peroxidation chain reactions, disrupting membrane function. We believe that the microvascular endothelial cell is a key target for these peroxidative processes. We further hypothesize that an environment that will enhance the 'dark' free radical lipid peroxidation reactions after the delivery of light will result in enhanced endothelial cell damage and death. The endothelial cell appears to be particularly sensitive to free radical-mediated oxidative stress. Therefore, in all experiments we will compare results obtained with microvascular endothelial cells to those from vascular epithelial cells and two tumor cell lines. L1210 murine leukemia and MCF-7 human breast carcinoma. The working hypothesis of this project will be tested with the following Specific Aims: I. Determine if pro-oxidants, such as iron, or ascorbate, or iron with ascorbate, will enhance the phototoxicity of PDT/HPD to cells, and conversely, determine if small-molecule antioxidants such as vitamin E, lazaroids, and BHT will provide protection against peroxidative phototoxicity. II. Determine if membrane-derived free radicals are produced in intact, functioning cells by PDT/HPD, and if pro-oxidants will enhance the free radical peroxidation processes, then determine if radical production correlates with phototoxicity. III. Determine if making cell membranes more oxidizable by increasing the proportion of polyunsaturated fatty acids will increase the phototoxicity of PDT/HPD. IV. We will use molecular biology techniques to modify the antioxidant enzyme profile of cells and determine if this will alter their sensitivity to PDT/HPD. V. Study in detail the fundamental chemical reactions that may be key to PDT/HPD phototoxicity.