Wilms tumour (WT), a childhood kidney cancer with embryonal origins, has been extensively characterised for genetic and epigenetic alterations, but a proportion of WTs still lack identifiable abnormalities. To uncover DNA methylation changes critical for WT pathogenesis, we compared the epigenome of fetal kidney with two WT cell lines, using methyl-CpG immunoprecipitation. We filtered our results to remove common cancer-associated epigenetic changes, and to enrich for genes involved in early kidney development. This identified four candidate genes that were hypermethylated in WT cell lines compared to fetal kidney, of which ESRP2 (epithelial splicing regulatory protein 2), was the most promising gene for further study. ESRP2 was commonly repressed by DNA methylation in WT, and this was shown to occur early in WT development (in nephrogenic rests). ESRP2 expression could be reactivated by DNA methyltransferase inhibition in WT cell lines. When ESRP2 was overexpressed in WT cell lines, it acted as an inhibitor of cellular proliferation in vitro, and in vivo it suppressed tumour growth of orthotopic xenografts in nude mice. RNA-seq of the ESRP2-expressing WT cell lines identified several novel splicing targets, in addition to well-characterised targets of ESRP2. We propose a model in which the mesenchymal to epithelial transition that is essential for early kidney development, can be disrupted in to generate WT, either by genetic abnormalities such as WT1 mutations, or by epigenetic defects, such as ESRP2 methylation.

中文翻译：

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DNA甲基化在Wilms肿瘤中对表皮剪接调节因子ESRP2进行表观遗传抑制。

Wilms肿瘤（WT）是一种具有胚胎起源的儿童肾脏癌，已被广泛表征为遗传和表观遗传学改变，但仍有一部分WTs缺乏可识别的异常。为了揭示对于WT发病机理至关重要的DNA甲基化变化，我们使用甲基CpG免疫沉淀法将胎儿肾脏的表观基因组与两种WT细胞系进行了比较。我们对结果进行了筛选，以消除常见的癌症相关表观遗传学变化，并丰富参与早期肾脏发育的基因。与胎儿肾脏相比，这确定了四种在WT细胞系中甲基化程度较高的候选基因，其中ESRP2（上皮剪接调节蛋白2）是最有希望研究的基因。ESRP2通常在WT中被DNA甲基化所抑制，并且显示在WT发育的早期（在肾原性休克中）发生。WT细胞系中的DNA甲基转移酶抑制作用可以重新激活ESRP2表达。当ESRP2在WT细胞系中过表达时，它在体外可作为细胞增殖的抑制剂，而在体内，它可抑制裸鼠体内原位异种移植物的肿瘤生长。表达ESRP2的WT细胞系的RNA序列除了确定的ESRP2靶标外，还鉴定了几个新的剪接靶标。我们提出了一个模型，其中对于早期肾脏发育必不可少的间质到上皮的转变，可以通过遗传异常（例如WT1突变）或通过表观遗传缺陷（例如ESRP2甲基化）而中断产生WT。它在体外可作为细胞增殖的抑制剂，在体内可抑制裸鼠体内原位异种移植物的肿瘤生长。表达ESRP2的WT细胞系的RNA序列除了确定的ESRP2靶标外，还鉴定了几个新的剪接靶标。我们提出了一个模型，其中对于早期肾脏发育必不可少的间质到上皮的转变，可以通过遗传异常（例如WT1突变）或通过表观遗传缺陷（例如ESRP2甲基化）而中断产生WT。它在体外可作为细胞增殖的抑制剂，在体内可抑制裸鼠体内原位异种移植物的肿瘤生长。表达ESRP2的WT细胞系的RNA序列除了确定的ESRP2靶标外，还鉴定了几个新的剪接靶标。我们提出了一个模型，其中对于早期肾脏发育必不可少的间质到上皮的转变，可以通过遗传异常（例如WT1突变）或通过表观遗传缺陷（例如ESRP2甲基化）而中断产生WT。