Microsatellites as EWIS/FLI response elements in Ewing's sarcoma
Microsatellites as EWIS/FLI response elements in Ewing's sarcoma
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DOI：
10.1073/pnas.0801073105
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发表时间：
2008-07-22
影响因子：
11.1
通讯作者：
Lessnick, Stephen L.
中科院分区：
文献类型：
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作者：
Gangwal, Kunal;Sankar, Savita;Lessnick, Stephen L.
ETS基因家族经常参与导致人类癌症的染色体易位，包括前列腺癌、白血病和肉瘤。然而，致癌ETS蛋白（dna结合转录因子）是肿瘤发生所必需的靶基因，其机制尚不清楚。尤文氏肉瘤是整个ETS相关肿瘤的典范，因为几乎所有病例都有涉及ETS基因的复发性染色体易位。在尤文氏肉瘤中最常见的易位是编码EWS/FLI致癌转录因子。我们采用全基因组定位技术（ChIP-chip）鉴定EWS/FLI直接结合的靶基因。对这些基因启动子的分析表明，高度重复的含有ggaa的元件（微卫星）具有显著的过度代表性。在平行方法中，我们发现EWS/FLI使用GGAA微卫星来调节一些靶基因的表达，包括NR0B1，这是Ewing肉瘤发生所需的基因。NR0B1启动子中的微卫星在体外和体内结合了EWS/FLI，并且是将EWS/FLI调控赋予报告基因的必要和充分条件。全基因组计算研究表明，GGAA微卫星富集在EWS/ fli上调基因附近，而不富集在下调基因附近。机制研究表明，EWS/FLI结合DNA并通过这些重复元件调节基因表达的能力取决于连续GGAA基序的数量。这些发现说明了ETS蛋白特异性的前所未有的途径和微卫星在肿瘤发生中的应用。
The ETS gene family is frequently involved in chromosome translocations that cause human cancer, including prostate cancer, leukemia, and sarcoma. However, the mechanisms by which oncogenic ETS proteins, which are DNA-binding transcription factors, target genes necessary for tumorigenesis is not well understood. Ewing's sarcoma serves as a paradigm for the entire class of ETS-associated tumors because nearly all cases harbor recurrent chromosomal translocations involving ETS genes. The most common translocation in Ewing's sarcoma encodes the EWS/FLI oncogenic transcription factor. We used whole genome localization (ChIP-chip) to identify target genes that are directly bound by EWS/FLI. Analysis of the promoters of these genes demonstrated a significant over-representation of highly repetitive GGAA-containing elements (microsatellites). In a parallel approach, we found that EWS/FLI uses GGAA microsatellites to regulate the expression of some of its target genes including NR0B1, a gene required for Ewing's sarcoma oncogenesis. The microsatellite in the NR0B1 promoter bound EWS/FLI in vitro and in vivo and was both necessary and sufficient to confer EWS/FLI regulation to a reporter gene. Genome wide computational studies demonstrated that GGAA microsatellites were enriched close to EWS/FLI-up-regulated genes but not down-regulated genes. Mechanistic studies demonstrated that the ability of EWS/FLI to bind DNA and modulate gene expression through these repetitive elements depended on the number of consecutive GGAA motifs. These findings illustrate an unprecedented route to specificity for ETS proteins and use of microsatellites in tumorigenesis.