Kinsey Michelle, Smith Richard, Iyer Anita K, McCabe Edward R B, Lessnick Stephen L
Department of Oncological Sciences, University of Utah School of Medicine, Salt Lake City, Utah, USA.
Cancer Res. 2009 Dec 1;69(23):9047-55. doi: 10.1158/0008-5472.CAN-09-1540. Epub 2009 Nov 17.
Most Ewing's sarcomas harbor chromosomal translocations that encode fusions between EWS and ETS family members. The most common fusion, EWS/FLI, consists of an EWSR1-derived strong transcriptional activation domain fused, in-frame, to the DNA-binding domain-containing portion of FLI1. EWS/FLI functions as an aberrant transcription factor to regulate genes that mediate the oncogenic phenotype of Ewing's sarcoma. One of these regulated genes, NR0B1, encodes a corepressor protein, and likely plays a transcriptional role in tumorigenesis. However, the genes that NR0B1 regulates and the transcription factors it interacts with in Ewing's sarcoma are largely unknown. We used transcriptional profiling and chromatin immunoprecipitation to identify genes that are regulated by NR0B1, and compared these data to similar data for EWS/FLI. Although the transcriptional profile overlapped as expected, we also found that the genome-wide localization of NR0B1 and EWS/FLI overlapped as well, suggesting that they regulate some genes coordinately. Further analysis revealed that NR0B1 and EWS/FLI physically interact. This protein-protein interaction is likely to be relevant for the development of Ewing's sarcoma because mutations in NR0B1 that disrupt the interaction have transcriptional consequences and also abrogate oncogenic transformation. Taken together, these data suggest that EWS/FLI and NR0B1 physically interact, coordinately modulate gene expression, and mediate the transformed phenotype of Ewing's sarcoma.
大多数尤因肉瘤存在染色体易位，这些易位编码EWS和ETS家族成员之间的融合蛋白。最常见的融合蛋白EWS/FLI由EWSR1衍生的强转录激活结构域与FLI1含DNA结合结构域的部分读框内融合而成。EWS/FLI作为一种异常转录因子发挥作用，调控介导尤因肉瘤致癌表型的基因。其中一个受调控的基因NR0B1编码一种共抑制蛋白，可能在肿瘤发生中发挥转录作用。然而，在尤因肉瘤中NR0B1调控的基因以及与其相互作用的转录因子很大程度上尚不清楚。我们利用转录谱分析和染色质免疫沉淀来鉴定受NR0B1调控的基因，并将这些数据与EWS/FLI的类似数据进行比较。尽管转录谱如预期那样重叠，但我们还发现NR0B1和EWS/FLI在全基因组水平上的定位也重叠，这表明它们协同调控一些基因。进一步分析显示NR0B1和EWS/FLI存在物理相互作用。这种蛋白质-蛋白质相互作用可能与尤因肉瘤的发生发展相关，因为破坏这种相互作用的NR0B1突变具有转录后果，并且还能消除致癌转化。综上所述，这些数据表明EWS/FLI和NR0B1存在物理相互作用，协同调节基因表达，并介导尤因肉瘤的转化表型。
