RADIOSENSITIVITY OF HUMAN GLIOMAS

放射治疗是仅次于手术的治疗恶性肿瘤的最有效方法。 脑瘤。然而，-20%的多形性胶质母细胞瘤(GBM)进展 在放射治疗过程中，表明这些损伤是 抗辐射的抗辐射的使用手术中获得的组织，我们将 开发实验室方法来识别这些肿瘤，并将 量化他们对辐射的反应。哺乳动物的辐射敏感性 细胞是在实验室通过测量细胞杀伤率来确定的。然而， 对于原发肿瘤组织，这种方法是有问题的，因为 对电镀效率和结果选择的研究很少 原始肿瘤细胞群的一小部分。尝试开发 以脑瘤细胞存活率为终点的预测分析有 失败了。我们认为，关键是要确定是否还有其他 定量测量可以用来预测肿瘤对辐射的反应 心理治疗。我们建议使用以下方法来评估本征辐射响应 更适合用于原发肿瘤标本：DNA倍体测量 脉冲场凝胶电泳法断链；NA超卷曲变化 通过核晕分析；染色体断裂和染色体断裂的测量 利用荧光原位杂交技术进行交流。我们会 用彗星试验测定选定肿瘤中的低氧分数。我们 将确定这些化验中的哪一种提供了相关信息 关于人脑肿瘤细胞的辐射反应，并建立 预测性分析。 由于在研究辐射敏感性方面存在的固有问题 在自然环境之外移植的肿瘤，我们将研究 低能量激光原位照射恶性脑瘤的可行性 术中使用能量X射线源并间隔采集组织以 测量DNA损伤和修复以及肿瘤缺氧情况。这可能是最理想的 研究单个肿瘤对辐射敏感性的方法。我们的 具体目标是：1)确定最佳实验条件 人脑肿瘤DNA损伤修复和缺氧程度的定量研究 作为异种移植模型生长的组织；2)确定哪种检测方法 在目标1中的研究表明(S)最有希望成为一种预测胰岛素抵抗的方法 异种移植模型的体内辐射反应性；3)DNA测量 新鲜GBM的损伤修复与染色体断裂与交换 使用所选分析的最佳条件的标本(S)；4) 探讨手术中照射人脑肿瘤的可行性 使用Allow能量X射线源和采集肿瘤组织进行分析 低氧组分与DNA损伤和修复；以及，5)将 目标3中获得的结果与肿瘤的BUDR标记指数和 潜在倍增时间、遗传异常、DNA修复活性 酶O/6-AT，并具有既定的临床预后指标，以及 放射治疗结果的临床测量。

Next to surgery, radiation is the most effective treatment for malignant brain tumors. Nonetheless, -20% of glioblastoma multiforme (GBM) progress during the course of radiation therapy, suggesting that these lesions are resistant to radiation. Using tissues obtained during surgery, we will develop laboratory methodologies for identifying these tumors, and will quantify their response to radiation. Radiation sensitivity of mammalian cells is determined in the laboratory by measuring cell killing. However, for primary tumor tissue this approach is problematic because of low plating efficiencies and the resultant selection for study of a very small fraction of the original tumor cell population. Attempts to develop predictive assays based on brain tumor cell survival as the end-point have failed. We believe that it is crucial to determine whether other quantitative measures can be used to predict tumor response to radiation therapy. We propose to assess intrinsic radiation response with methods more suitable for use in primary tumor samples: measurement of DNA double strand breaks by pulsed field gel electrophoresis; NA supercoiling changes by the nucleoid halo assay; and measurement of chromosomal breaks and exchanges using fluorescence in situ hybridization techniques. We will determine hypoxic fraction in selected tumors using the comet assay. We will determine which of these assays provides relevant information regarding the radiation response of human brain tumor cells and establish predictive assays. Because of the problems inherent in studying radiation sensitivity of explanted tumors outside of their natural milieu, we will study the feasibility of irradiating malignant brain tumors in situ with a low energy X-ray source intraoperatively and harvesting tissue at intervals to measure DNA damage and repair and tumor hypoxia. This may be the ideal way to study the individual tumor's sensitivity to radiation. Our specific aims are: 1) to define the optimal experimental conditions to quantify DNA damage and repair and hypoxic fraction in human brain tumor tissue grown as a xenograft model; 2) to determine which of the assays studied in Aim 1 show(s) the most promise as a predictive assay for in vivo radiation responsiveness in xenograft models; 3) to measure DNA damage and repair and chromosome breaks and exchanges in fresh GBM specimens using optimal conditions for the chosen assay(s); 4) to investigate the feasibility of irradiating human brain tumors at surgery with allow energy X-ray source and harvesting tumor tissue for assays of hypoxic fraction and DNA damage and repair; and, 5) to correlate the results obtained in Aim 3 with the tumor's BUdR labeling index and potential doubling time, genetic aberrations, activity of the DNA repair enzyme O/6-AT, and with established clinical indicators of prognosis, and clinical measures of radiation therapy outcome.