REGULATION OF RADIORESISTANCE IN HUMAN RENAL CANCER CELL

放射治疗是癌症的一种重要治疗手段。它的 然而，有效性受到了以下固有阻力的限制 某些肿瘤细胞受到电离辐射。虽然因素多种多样 口述对辐射的反应，本研究将重点放在重要性上 人原癌基因c-raf-1(Raf-1)产物在细胞内的表达 对伽马辐射的反应。对负性调节的观察 反义基因对人肿瘤细胞辐射抗性的影响 C-RAF-1基因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，而且因为一种 重要的转录因子AP-1需要Raf蛋白激酶， 第二个假说是伽马辐射调节Raf-1蛋白 激活剂。反过来，该激酶可能在辐射后的 细胞周期、DNA合成和/或转录的变化。 肾细胞癌(RCC)，一种进展性和相对放射抵抗 疾病，将被用作人类肿瘤细胞模型来检验其作用 Raf-1在辐射抗性调节(AIM-1)中的作用 伽马辐射对Raf-1生化和功能的影响(AIM 2)，以及 检测放射生物癌基因介导的正常人乳腺癌细胞转化 肾细胞(AIM 3)。RAF-1的功能将由表达调控 含有缺失或缺失的新型Raf特异性显性负性突变体 微妙的氨基酸替换，以及正义/反义c-raf-1的cDNA.这个 表达，翻译后修饰，丝氨酸/苏氨酸激酶 Raf-1的活性、亚细胞定位及细胞周期调控 将会被检查。分析的放射生物学反应将包括 辐射存活剂量效应与亚致死剂量的诱导与修复 损害，潜在的致命损害，和DNA链断裂。这些研究 会对Raf-1蛋白的作用有更好的理解吗？ 激酶在辐射抗性调节中的作用和(Ii)促进我们的 对分子靶标的了解，以及对分子作用的了解 电离辐射。目前的调查应该会引导我们开始 阐明细胞内信号中Raf-1蛋白激酶的底物 辐射抗性的转导途径(S)。所获得的信息可能 促进制定有效放射治疗的新战略。

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.