HYPOXIC STRESS MECHANISMS IN RADIATION AND CHEMOTHERAPY

放射治疗和化疗中的缺氧应激机制

• 批准号: 6171902
• 负责人: BRIAN J MURPHY
• 金额: $ 25.37万
• 依托单位: SRI INTERNATIONAL
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-08-12 至 2001-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6171902
• 关键词: animal genetic material tag; antineoplastics; antisense nucleic acid; apoptosis; drug resistance; gene induction /repression; genetic promoter element; hepatocellular carcinoma; human genetic material tag; hypoxia; ionizing radiation; metallothionein; neoplasm /cancer genetics; neoplasm /cancer pharmacology; nucleic acid sequence; physiologic stressor; protein isoforms; radiation resistance; radiopharmacology; site directed mutagenesis; southern blotting; squamous cell carcinoma; tissue /cell culture; transcription factor; western blottings

Resistance to chemotherapeutic drugs and radiation is the most important factor in failures of conventional anticancer therapies to cure. A growing body of evidence suggests many human tumors contain a significant fraction of hypoxic cells that can directly affect therapeutic responsiveness. The detailed nature of these hypoxia- dependent resistance phenotypes remains unclear but involves a set of diverse proteins, called oxygen-regulated proteins (ORPs), whose expression is induced in response to transient and chronic hypoxia. This proposal is based on the hypothesis that the overexpression of a major isoform of metallothionein (MT-IIA) in hypoxic microenvironments of human tumors selects for malignant phenotypes. Proposed studies include experiments to precisely define the putative hypoxic responsive element(s) of the human MT-IIA 5'- regulatory region and to characterize the possible role of a metal-responsive element and a putative oxidant/ antioxidant response element in this regulation. The identities and properties of associated transcription factors will also be investigated. A second aim will extend ongoing studies of the cytoprotective role of transiently overexpressed MTs induced by hypoxia to subsequent exposures to reoxygenation, antineoplastic agents, or radiation exposure. This cytoprotective effect will be investigated by clonogenic and apoptosis assays, analysis of MI subcellular distributions, and monitoring of MT and apoptosis-associated protein expression patterns in a series of experiments using transgenic MT wild-type and knockout mouse cells and antisense-treated human squamous carcinoma and hepatoma cells. A detailed understanding of the genetic regulation and mechanisms of MT involvement in drug and radiation resistance in stressed regions of solid tumors will result in novel prognostic and therapeutic strategies. For example, these studies will provide a foundation for creating gene therapy approaches to cancer in which vector constructs containing the hypoxic/redox response elements that activate genes can be used for sensitizing tumor cells to other therapeutic agents.

对化疗药物和放射线的抵抗力最强 传统抗癌疗法失败的重要因素 治愈。 越来越多的证据表明许多人类肿瘤含有 缺氧细胞的很大一部分可以直接影响 治疗反应性。这些缺氧的详细性质 依赖性耐药表型仍不清楚，但涉及一组 多种蛋白质，称为氧调节蛋白（ORP），其 表达是响应短暂和慢性缺氧而诱导的。 该提议基于以下假设：a 的过度表达 缺氧微环境中金属硫蛋白 (MT-IIA) 的主要亚型 的人类肿瘤选择恶性表型。拟议的研究 包括精确定义假定的缺氧反应的实验 人类 MT-IIA 5'- 调控区的元件以及 描述金属响应元素的可能作用和 该调节中推定的氧化剂/抗氧化反应元件。这 相关转录因子的身份和特性也将 被调查。第二个目标是扩展正在进行的研究 缺氧诱导的瞬时过表达 MT 的细胞保护作用 随后暴露于再氧合、抗肿瘤药物或 辐射暴露。这种细胞保护作用将通过 克隆形成和细胞凋亡测定、MI 亚细胞分析 MT 和凋亡相关蛋白的分布和监测 使用转基因 MT 进行的一系列实验中的表达模式 野生型和基因敲除小鼠细胞以及反义处理的人鳞状细胞 癌细胞和肝癌细胞。对遗传的详细了解 MT参与药物和放射的调控及机制 实体瘤受压区域的抵抗力将产生新的 预后和治疗策略。例如，这些研究将 为创建癌症基因治疗方法奠定基础 哪个载体构建体含有缺氧/氧化还原反应元件 激活基因可用于使肿瘤细胞对其他基因敏感 治疗剂。