STATUS OF P53 IN A LFS CANCER PRONE FAMILY

遗传易感性的分子机制研究进展 癌症在很大程度上是通过识别和分析 视网膜母细胞瘤等家族性癌症综合征的易感基因， 肾母细胞瘤、I型神经纤维瘤病和家族性结肠息肉病。这个 肿瘤抑制基因p53已被证明在广泛的 各种散发性肿瘤。在这些情况下，p53的一个等位基因是 丢失了，剩下的等位基因获得了体细胞突变。这个 癌症易感家系中P53胚系突变的鉴定 Li-Fraumeni综合征(LFS)为P53引入了一个新的角色，即 对癌症的遗传易感性。我们最近的研究表明， 来自癌症患者的正常皮肤成纤维细胞(NSFs)- 易感家系表达低水平的野生型(Wt)和突变型(Mt)p53 与正常人检测到的wt p53水平相当的蛋白质 细胞。此外，肿瘤起源于四个不同的两个生殖层 该家族中的个体表现出wt p53等位基因的丢失和 Mt等位基因的保留。我们还知道，许多突变 在LFS中发现的P53家族似乎具有跨显性效应 WT-P53的体外检测。 了解胚系p53突变在遗传易感性中的作用 和肿瘤的发生，我们建议分析生物学和生化 在这个患有LFS的癌症易感家系中发现了mt p53的特征。 因此，我们将检测SV40T抗原、MDM-2和序列特异性DNA P53在这些神经干细胞中的结合特性，并评价其作用 WT/MT表型对细胞周期进程和细胞凋亡的影响。这样的分析 将提供有关mt p53对wt功能的影响的信息。 杂合子情况下的P53基因。我们会把这些研究扩展至其他本地家庭。 家庭，以了解这些调查结果的广泛影响 遗传性的p53突变。由于P53蛋白表现出 转录因子并在体外与特定的DNA序列结合， 同时内源性表达mt和wt p53的家族神经干细胞提供了良好的 用于识别受基因调控的靶基因的实验系统 P53基因突变。这些基因的状态将由 对先前鉴定的细胞生长的表达进行分析 相关基因或差异表达的基因 在家庭NSFs中进行监管(重量/公吨)。因此，本文中提出的实验 应用程序不仅应该用来增加我们对 Mt-P53在易感性、肿瘤形成和肿瘤形成中的功能意义 患有LFS的癌症易感家庭的进展，但也应该产生 与P53在肿瘤发生中的作用有关的信息。

The studies of the molecular mechanism of inherited susceptibility to cancer are significantly aided by the identification and analysis of predisposing genes from familial cancer syndromes such as retinoblastoma, Wilms'Tumors, Neurofibromatosis Type I, and Familial Polyposis Coli. The tumor suppressor gene p53 has been shown to frequently altered in a wide variety of sporatic tumors. In these instances, one allele of p53 has been lost and the remaining allele has acquired a somatic mutation. The identification of a germ-line p53 mutation in cancer-prone families with Li-Fraumeni syndrome (LFS) has introduced a new role for p53, i.e., a role in genetic susceptibility to cancer. Our recent studies show that the normal skin fibroblast (NSFs) cells derived from individuals in the cancer- prone family express low levels of both wild-type (wt) and mutant (mt) p 53 protein at levels comparable to that of the wt p53 detected in normal cells. Furthermore, tumors arising from two germ-layers in four different individuals in this family exhibited the loss of the wt p53 allele and the retention of the mt allele. We have also known that many of the mutations in p53 found in LFS families appear to have a transdominant effect over the wt p53 in in vitro assays. To understand the role of germ-line p53 mutations in genetic predisposition and tumorigenesis, we propose to analyze the biological and biochemical characteristics of mt p53 found in this cancer-prone family with LFS. Therefore, we will examine the SV40 T Ag, MDM-2 and sequence specific DNA binding properties of p53 in these NSFs, and evaluate the effect of this wt/mt phenotype on cell cycle progression and apoptosis. Such analysis will provide information on the effects of mt p53 on the functions of wt p53 in a heterozygous situation. We will extend these studies to other LFS families in order to understand the broad implications of these findings for inherited p53 mutations. Since the p53 protein exhibits the properties of a transcription factor and binds to specific DNA sequences in vitro, the family NSFs with endogenous expression of both mt and wt p53 provide a good experimental system with which to identify target genes modulated by mutation in p53. The status of such genes will be evaluated by the analysis of either the expression of previously identified cell growth associated genes or the expression of genes which are differentially regulated in family NSFs (wt/mt). Thus, the experiments proposed in this application should serve not only to increase our understanding of the functional implications of mt p53 in predisposition, tumor formation and progression in cancer-prone families with LFS but should also yield information relevant to the function of p53 in tumorigenesis in general.