Mechanisms in Wilms Tumorigenesis

肾母细胞瘤是一种儿童胚胎性肾癌，与11号染色体短臂上的分子遗传异常有关。该肿瘤与泌尿生殖系统的异常有关，从我们和其他人对WT1基因的克隆和鉴定中可以明显看出共同的遗传起源。WT1仅表达于浓缩的后肾间充质或发育中的肾小球。因此，它必须对后肾间充质和输尿管上皮芽相互作用后的诱导信号作出反应，并可能调节与分化和形态发生有关的其他基因的表达。这个项目的长期目标是通过识别WT1靶基因并确定它们在肾脏发生和肿瘤发生中的作用，来确定WT1如何调节这一过程。这些目标将通过追求以下具体目标来实现。为了验证WT1同时激活和抑制靶基因以调控肾脏发生的假设，我们将通过研究WT1的启动子，检测它们在肾母细胞瘤和体外和体内肾脏形成过程中的表达，从基因芯片分析中鉴定出潜在的WT1靶基因。在第二个目标中，我们将使用染色质沉淀来识别WT1的直接转录靶标基因。在第三个目标中，我们将在Wilms肿瘤细胞系中调节WT1和P53的表达，并确定对转录谱的影响。我们还将开发肾脏特异的cDNA阵列和特异性消融选择性转录本的方法。这些拟议的研究有望为WT1作为转录调节因子的作用提供新的见解，并导致识别与肾脏发生和肾母细胞瘤发生有关的新基因。

Wilms tumor is an embryonal kidney cancer of children that has been linked to molecular genetic abnormalities on the short arm of chromosome 11. This tumor is associated with anomalies in the urogenitary system and a shared genetic origin has become evident from the cloning and characterization of the WT1 locus by ourselves and others. WT1 is restricted in expression to the condensing metanephric mesenchyme or developing glomeruli. Thus it must respond to induction signals following interaction of the metanephric mesenchyme and the epithelial ureteric bud and likely regulate the expression of other genes involved in differentiation and morphogenesis. The long term objective of this project is to determine how the WT1 regulates this process by identifying WT1-target genes and defining their role in nephrogenesis and tumorigenesis. These objectives will be achieved by pursuing the following specific aims. To test the hypothesis that WT1 both activates and represses target genes to regulate nephrogenesis in Aim one we will characterize genes identified as potential WT1 targets from GeneChip analyses by studying their promoters, examining their expression in Wilms tumors and during nephrogenesis in vitro and in vivo. In aim two we will use chromatin precipitation to identify genes that are direct transcriptional targets for WT1. In aim three we will modulate WT1 and p53 expression in a Wilms tumor cell line and determine effects on transcript profiles. We will also develop kidney specific cDNA arrays and methods for specifically ablating selective transcripts. The proposed studies promise to provide new insights into the role of WT1 as a transcriptional regulator and to lead to the identification of novel genes involved in nephrogenesis and Wilms tumorigenesis.