REGULATION OF RADIORESISTANCE IN HUMAN RENAL CANCER CELL

放射治疗是癌症的重要治疗方式。 其 然而，有效性受到固有阻力的限制， 某些肿瘤细胞的电离辐射。 虽然各种因素 决定对辐射的反应，这项研究将集中在重要性 人原癌基因c-raf-1（Raf-1）的产物在细胞中的表达 对伽马射线的反应 负调节的观察 反义核酸转染的人肿瘤细胞辐射抗性的研究 c-raf-1 cDNA为辐射抗性假说提供了基础， 与Raf-1丝氨酸/苏氨酸蛋白激酶的功能有关。 因为辐射会诱导某些基因的转录， 重要的转录因子AP-1需要Raf蛋白激酶， 第二个假设是γ射线调节Raf-1蛋白 激酶。 激酶反过来可能在照射后的细胞凋亡中起作用。 细胞周期、DNA合成和/或转录的变化。 肾细胞癌（RCC）是一种进行性和相对放射抗性的肿瘤， 疾病，将被用作人类肿瘤细胞模型，以检查的作用， Raf-1在调节辐射抗性（AIM 1）中的作用，以确定Raf-1在辐射抗性调节中的作用。 γ辐射对Raf-1生物化学和功能的影响（AIM 2），以及 检测放射生物致癌基因介导的正常 肾细胞（AIM 3）。 Raf-1的功能将受到以下表达的调控： 含有缺失的新的Raf-specific显性负突变体，或 细微的氨基酸取代和有义/反义c-raf-1cDNA。 的 表达，翻译后修饰，丝氨酸/苏氨酸激酶 Raf-1的活性、亚细胞定位和细胞周期调控 将被审查。 分析的放射生物学反应将包括 辐射存活剂量反应，以及亚致死剂量的诱导和修复 损伤、潜在致命损伤和DNA链断裂。 这些研究 （i）更好地理解Raf-1蛋白的作用 激酶在调节辐射抗性和（ii）推进我们的 分子目标和机械的知识， 电离辐射 目前的调查应该会让我们开始 阐明Raf-1蛋白激酶在细胞内信号中的底物 转导途径对辐射抗性的影响。 获得的信息可能 促进制定有效放射治疗的新策略。

Radiation therapy is an important treatment modality for cancer. Its effectiveness has been restricted, however, by the inherent resistance of certain tumor cells to ionizing radiation. Although diverse factors dictate the response to radiation, this study will focus on the importance of the product of the human proto-oncogene c-raf-1 (Raf-1) in the cellular response to gamma radiation. The observation of the negative regulation of radiation resistance in human tumor cells transfected with antisense c-raf-1 cDNA provides a basis for the hypothesis that radiation resistance is linked to the function of Raf-1 serine/threonine protein kinase. Because radiation induces transcription of certain genes, and because an important transcription factor, AP-1, requires Raf protein kinase, the second hypothesis is that the gamma-radiation modulates Raf-1 protein kinase. The kinase, in turn, may play a role in the post-irradiation changes in cell cycle, DNA synthesis and/or transcription. Renal cell carcinoma (RCC), a progressive and relatively radioresistant disease, will be used as a human tumor cell model to examine the role of Raf-1 in the regulation of radiation resistance (AIM 1), to determine the effects of gamma-radiation on Raf-1 biochemistry and function (AIM 2), and to examine the radiobiological oncogene-mediated transformation of normal renal cells (AIM 3). Raf-1 function will be regulated by the expression of novel Raf-specific dominant negative mutants containing deletions or subtle amino acid substitutions, and sense/antisense c-raf-1 cDNA. The expression, posttranslational modification, serine/threonine kinase activity, subcellular localization and the cell cycle regulation of Raf-1 will be examined. Radiobiological responses analyzed will include the radiation survival dose response, and the induction and repair of sublethal damage, potentially lethal damage, and DNA strand breaks. These studies will (i) generate a better understanding of the role of Raf-1 protein kinase in the regulation of radiation resistance and (ii) advance our knowledge of the molecular targets and mechanically, of the action of ionizing radiation. The current investigations should lead us to begin to elucidate substrates of Raf-1 protein kinase in the intracellular signal transduction pathway(s) to radioresistance. The information gained may facilitate the development of new strategies for effective radiotherapy.