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。这种肿瘤与泌尿生殖系统异常有关，从我们和其他人对WT1基因座的克隆和表征中可以看出，它们具有共同的遗传起源。WT1的表达仅限于凝缩后肾间质或发育中的肾小球。因此，它必须响应后肾间质和输尿管上皮芽相互作用后的诱导信号，并可能调节其他参与分化和形态发生的基因的表达。该项目的长期目标是通过鉴定WT1靶基因并确定其在肾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下列具体目标来实现。为了验证在Aim 1中WT1激活和抑制靶基因来调节肾发生的假设，我们将通过研究基因芯片分析中确定的潜在WT1靶基因的启动子，检测它们在Wilms肿瘤中的表达以及在体外和体内的肾发生过程中。在目标二中，我们将使用染色质沉淀来识别WT1的直接转录目标基因。在目标三中，我们将调节WT1和p53在Wilms肿瘤细胞系中的表达，并确定对转录谱的影响。我们还将开发肾脏特异性cDNA阵列和方法来特异性地消融选择性转录本。提出的研究有望为WT1作为转录调节因子的作用提供新的见解，并导致识别参与肾发生和Wilms肿瘤发生的新基因。

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.