P53 function and apoptosis in melanoma

描述：(申请者描述)P53肿瘤抑制基因诱导 当被DNA损伤激活时，细胞周期停滞和/或凋亡。因为 癌症是用DNA损伤剂治疗的，治疗的结果是 显著受P53诱导细胞凋亡能力的影响 造成DNA损伤。因此，表达野生型p53的肿瘤往往反应更好。 并且比表达突变不活跃的肿瘤更具放射敏感性 P53。一个例外是黑色素瘤；这些肿瘤表达野生型p53，但 具有极强的抗辐射能力。我们的目标是在分子水平上理解为什么 野生型P53不能诱导DNA损伤的黑色素瘤细胞凋亡。在……里面 正常细胞，依赖于p53的细胞凋亡反应发生在DNA损伤 三个步骤：a)增加P53蛋白的半衰期，导致 蛋白质水平升高，P53与特定DNA的亲和力增强 序列；b)P53与特定基因的调节区和 诱导这些基因的转录；)通过诱导细胞凋亡 P53诱导基因的蛋白质产物。我们的初步结果表明 在黑色素瘤细胞中，即使在没有DNA损伤的情况下，p53也有 对DNA有很高的亲和力。我们还发现了一个缺陷，那就是 P53激活特定靶基因的转录，如MDM2基因。 因此，我们假设黑色素瘤的辐射抗性是由于两种 MEL无核细胞向黑色素瘤转化过程中的分子事件 细胞：a)DNA损伤反应中的异常，导致本体 P53的激活；以及b)P53作为一种 P53靶基因全套转录因子，允许 黑色素瘤细胞逃脱细胞凋亡。为了解决这一假设，我们将：1) 分析黑色素瘤进展过程中P53对DNA损伤的异常反应 并确定其是否可作为诊断和预后的标记物； 确定P53诱导表达的能力是否存在缺陷 全套p53靶基因是黑色素瘤细胞逃逸的基础 从依赖于p53的细胞凋亡；以及3)确定改变的DNA结合 序列特异性和/或转录活性受损是导致 P53不能诱导完整的P53靶基因的表达 基因。这些实验将有助于确定治疗策略，旨在 恢复黑色素瘤细胞的凋亡。

DESCRIPTION: (Applicant's Description) The p53 tumor suppressor gene induces cell cycle arrest and/or apoptosis when activated by DNA damage. Because cancer is treated with DNA-damaging agents, the outcome of therapy is significantly influenced by the ability of p53 to induce apoptosis in response to DNA damage. Thus, tumors that express wild-type p53 tend to respond better to therapy and are more radiosensitive than tumors expressing mutant inactive p53. One exception 5 melanoma; these tumors express wild-type p53, but are extremely radioresistant. Our goal is to understand at he molecular level why wild-type p53 does not induce apoptosis of melanoma cells with damaged DNA. In normal cells, p53-dependent apoptosis in response to DNA damage occurs in three steps: a) increase in the halffife of the p53 protein, leading to increased protein levels, and increase in the affinity of p53 for specific DNA sequences; b) binding of p53 to regulatory regions of specific genes and induction of transcription of these genes; ) induction of apoptosis by the protein products of the p53-inducible genes. Our preliminary results suggest that in melanoma cells, p53, even in the absence of DNA damage, has constitutively high affinity for DNA. We also Find a defect in the ability of p53 to activate transcription of specific target genes, such as the mdm2 gene. We therefore hypothesize that the radioresistance of melanoma is due to two molecular events that occur during Lransformation of mel anocytes to melanoma cells: a) an aberration in the DNA damage response leading to onstitutive activation of p53; and b) a defect in the ability of p53 to function as a transcription factor for the full repertoire of p53-target genes, allowing melanoma cells to escape apoptosis. To address this hypothesis we will:1) analyze the aberrant response of p53 to DNA damage during melanoma progression and determine whether it an be used as a diagnostic and prognostic marker; 2) determine whether a defect in the ability of p53 to induce expression of the full repertoire of p53-target genes underlies the escape of melanoma cells from p53-dependent apoptosis; and 3) determine whether altered DNA binding sequence-specificity and/or compromised transcriptional activity underlie the inability of p53 to induce expression of the full repertoire of p53-target genes. These experiments will help identify therapeutic strategies aimed at restoring apoptosis to melanoma cells.