FREE RADICALS IN HYPERTHERMIA

治疗性热疗是为治疗疾病而产生的超生理温度。目前，热疗被研究为许多癌症治疗(如前列腺癌)的辅助治疗，包括放射治疗和光动力治疗。热休克的氧化应激理论有以下几个组成部分：热休克可以产生自由基和相关的氧化剂；这些物种可以引起热所产生的部分细胞损伤；如果诱导保护蛋白，细胞损伤是可以容忍的。本申请中提出的研究旨在测试热休克的氧化应激理论。我们假设，细胞在高温(例如41-45摄氏度)下会产生更多的自由基通量。因此，利用培养的细胞，我们将：使用电子顺磁共振检测和鉴定这些自由基；检查细胞中的总通量或氧化剂；并检查细胞对这些氧化剂的反应。我们假设抗氧化酶超氧化物歧化酶(SOD)和/或谷胱甘肽过氧化物酶(GPX)水平的升高会导致耐热性，而SOD和/或GPX水平的降低会导致热敏感性。我们将通过使用分子生物学技术改变细胞中的抗氧化酶水平来检验这一假设，然后测试它们的耐热性。对于那些能够产生一氧化氮的细胞，我们假设高温会导致一氧化氮的产生增加，在某些情况下，这可能是细胞毒性的。我们将检测培养的内皮细胞(和其他适当的)细胞在高温下产生一氧化氮的能力，并确定这种一氧化氮是否有害。如果ROS很重要，那么我们可以预测，在热应激的细胞中，催化铁会增加，从而放大热处理引发的氧化。我们将研究这种铁在高温期间产生细胞毒性中的作用，并确定催化铁水平的调节是否会改变细胞的耐热性。这项拟议的研究计划旨在检验这样一种假设，即自由基和相关氧化剂的产生是高温有害影响的一个重要方面。

Therapeutic hyperthermia is the production of super-physiological temperatures for treatment of disease. Hyperthermia is currently being investigated as an adjuvant for many cancer therapies, (e.g. prostate cancer) including radiation and photodynamic therapy. The oxidative stress theory of heat shock has the following components: heat shock can produce free radicals and related oxidants; these species can cause part of the cellular injury produced by heat; and cellular injury can be tolerated if protective proteins are induced. The research proposed in this application is designed to test the oxidative stress theory of heat shock. We hypothesize that cells subjected to hyperthermia (e.g., 41-45 C) will produce an increased flux of free radicals. Thus, using cultured cells we will: detect and identify these free radicals using electron paramagnetic resonance; examine the overall flux or oxidants in cells; and examine the response of cells to these oxidants. We hypothesize that elevated levels of the antioxidant enzymes superoxide dismutase (SOD) and/or glutathione peroxidase (GPx) will lead to thermotolerance, whereas depressed levels of SOD and/or GPx will lead to heat sensitivity. We will test this hypothesis by using molecular biology techniques to alter the antioxidant enzyme level in cells and then test their thermotolerance. For those cells capable of generating nitric oxide, we hypothesize that heat will result in increased production of nitric oxide, which under certain circumstances, can be cytotoxic. We will examine the ability of cultured endothelial (and other appropriate) cells to generate nitric oxide in response to hyperthermia and determine if this nitric oxide is detrimental. If ROS are important, then we would predict that catalytic iron would increase in heat-stressed cells, thereby amplifying the oxidations initiated by heat treatment. We will examine the role of this iron in producing cell toxicity during hyperthermia and determine if modulation of catalytic iron levels will alter the thermotolerance of cells. This proposed research program is designed to test the hypothesis that production of free radicals and related oxidants is an important aspect of the detrimental effects of hyperthermia.