P53 function and apoptosis in melanoma

描述：（申请人的描述）p53肿瘤抑制基因诱导 细胞周期停滞和/或凋亡。因为 癌症用DNA损伤剂治疗，治疗的结果是 p53诱导细胞凋亡的能力显著影响 DNA损伤。因此，表达野生型p53的肿瘤倾向于更好地响应 并且比表达突变失活的肿瘤更放射敏感 第53页。一个例外是5例黑色素瘤;这些肿瘤表达野生型p53，但 非常抗辐射我们的目标是在分子水平上理解为什么 野生型p53不诱导DNA受损的黑素瘤细胞凋亡。在 正常细胞中，p53依赖性细胞凋亡响应DNA损伤发生在 三个步骤：a）增加p53蛋白的半衰期，导致 蛋白质水平增加，p53对特定DNA的亲和力增加 序列; B）p53与特定基因的调节区的结合，和 诱导这些基因的转录;）通过这些基因诱导细胞凋亡。 p53诱导基因的蛋白产物。我们的初步结果表明 在黑色素瘤细胞中，即使没有DNA损伤， 对DNA的组成型高亲和力。我们还发现了一个缺陷， p53以激活特定靶基因如mdm 2基因的转录。 因此，我们假设黑色素瘤的放射抗性是由于两个 黑色素细胞向黑色素瘤转化过程中发生的分子事件 细胞：a）DNA损伤反应中的畸变，导致结构性 p53的活化;和B）p53作为免疫调节剂发挥功能的能力的缺陷 p53靶基因的完整库的转录因子，允许 黑色素瘤细胞逃避凋亡。为了解决这个假设，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 并确定其是否可用作诊断和预后标志物; 2） 确定是否存在p53诱导表达的能力缺陷， 完整的p53靶基因库是黑色素瘤细胞逃逸的基础 从p53依赖性细胞凋亡;和3）确定是否改变DNA结合 序列特异性和/或受损的转录活性是 p53不能诱导p53-靶的全部库的表达 基因.这些实验将有助于确定治疗策略， 恢复黑素瘤细胞的凋亡。

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.