SUBCELLULAR TARGETS AND PDT INDUCED APOPTOSIS

描述：该项目旨在提供以下信息 光动力疗法诱导细胞死亡的机制(S)。这个 长期目标是提高对选择性肿瘤的理解 PDT介导的肿瘤根除，包括耐药肿瘤细胞 化疗或电离辐射。虽然最初人们认为 即PDT引起了坏死性反应，PDT诱导的细胞凋亡现在已经 在体内和细胞内的几种动物肿瘤系统中的描述 文化。尽管光动力疗法并不总是表现为启动细胞凋亡 反应，这可能与化验程序有关，或者 光损伤的部位。因此，他们计划使用各种方法 目的：探讨光动力疗法对细胞死亡的影响及S所采用的细胞死亡方式。他们的电流 假设(1)光动力疗法后细胞凋亡的表达依赖于 光损伤的亚细胞位置(S)；(2)线粒体光损伤导联 对非常快速的凋亡反应；(3)后者由释放触发 细胞色素c和其他来自线粒体膜的因子 激活胞质半胱氨酸天冬氨酸酶；(4)同时发生膜的光损伤 延缓或取消作为释放膜衍生的细胞的凋亡反应 产品，如神经酰胺，受损。他们建议后者 这些因素可以改变细胞凋亡的阈值或加速这一过程。 高剂量的光动力疗法可能会抑制细胞凋亡，因为特异性会丧失。他们的 假说认为，蛋白质磷酸化在光动力转换中的作用 诱导的凋亡程序可能是外周的，带有一定的激酶和 引起非特异性细胞毒性的磷酸酶抑制剂 细胞凋亡阈值的改变。提出了三个目标。目标 1旨在更好地了解网站(S) 光损伤作为细胞凋亡反应的决定因素。他们会 扩大已经对小鼠白血病进行的研究，并扩大 确定一套不同的本地化标准的工作范围 适用于非淋巴系来源的细胞类型。Aim 2考察了 线粒体光损伤诱导细胞凋亡的机制 小鼠白血病的反应和同时发生的细胞膜光损伤 可以延迟此响应。在目标3中，他们转向对光动力疗法的研究- 对常规药物无反应的细胞系诱导的细胞凋亡反应 化疗和亚系P53和bcl2的表达不同。CA PDT 在程序的后期阶段启动细胞凋亡，以绕过 耐药与高的细胞凋亡阈值有关？既然是这样 该提案涉及对他们先前研究的重点进行改变 在指导方面，已邀请三名顾问(两名当地人)协助 实验结果的设计和解释。

DESCRIPTION: This project is designed to provide information on mechanism(s) of cell death induced by photodynamic therapy (PDT). The long-range goal is an improved understanding of the selective tumor eradication mediated by PDT, including neoplastic cells resistant to chemotherapy or ionizing radiation. While it was initially believed that PDT caused a necrotic response, PDT-induced apoptosis has now been described in several animal tumor systems, both in vivo and in cell culture. Although PDT does not always appear to initiate an apoptotic response, this may be related to the assay procedure, or differences in sites of photodamage. They therefore plan to use a variety of methods to assess both effects of PDT and mode(s) of cell death. Their current hypothesis is that (1) expression of apoptosis after PDT depends on the subcellular site(s) of photodamage; (2) mitochondrial photodamage leads to very rapid apoptotic response; (3) the latter is triggered by release of cytochrome c and other factors from mitochondrial membranes which activate cytosolic caspases; (4) concurrent membrane photodamage will delay or abolish the apoptotic response as release of membrane-derived products, e.g. ceramide, is impaired. They propose that the latter factors can alter the apoptotic threshold or accelerate the program. High PDT doses may inhibit apoptosis, as specificity is lost. Their hypothesis suggests that the role of protein phosphorylation in the PDT- induced apoptotic program may be peripheral, with certain kinase and phosphatase inhibitors responsible for non-specific cytotoxicity or alterations in the apoptotic threshold. Three aims are proposed. Aim 1 is designed to provide a better understanding of site(s) of photodamage as a determinant of the apoptotic response. They will amplify studies already done with the murine leukemias, and extend the scope of work to determine if a different set of localization criteria apply to cell types of non-lymphoid origin. Aim 2 examines the mechanism whereby mitochondrial photodamage elicits an apoptotic response in the murine leukemias, and concurrent membrane photodamage can delay this response. In Aim 3, they turn to the study of the PDT- induced apoptotic response in cell lines non-responsive to conventional chemotherapy and sublines varying in p53 and bcl-2 expression. Ca PDT initiate apoptosis at such a late stage in the program as to circumvent drug resistance associated with a high apoptotic threshold? Since this proposal involves a change in focus from their previous research direction, three consultants (two locals) have been solicited to aid in the design and interpretation of experimental results.