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Abstract：
The mechanistic basis for the metastasis of Ewing sarcomas remains poorly understood, as these tumors harbor few mutations beyond the chromosomal translocation that initiates the disease. Instead, the epigenome of Ewing sarcoma cells reflects the regulatory state of genes associated with the DNA-binding activity of the fusion oncoproteins EWSR1::FLI1 or EWSR1::ERG. In this study, we examined the EWSR1::FLI1/ERG\'s repression of transcription factor genes, concentrating on those that exhibit a broader range of expression in tumors than in Ewing sarcoma cell lines. Focusing on one of these target genes, ETS1, we detected EWSR1::FLI1 binding and an H3K27me3-repressive mark at this locus. Depletion of EWSR1::FLI1 results in ETS1\'s binding of promoter regions, substantially altering the transcriptome of Ewing sarcoma cells, including the upregulation of the gene encoding TENSIN3 (TNS3), a focal adhesion protein. Ewing sarcoma cell lines expressing ETS1 (CRISPRa) exhibited increased TNS3 expression and enhanced movement compared with control cells. Visualization of control Ewing sarcoma cells showed a distributed vinculin signal and a network-like organization of F-actin; in contrast, ETS1-activated Ewing sarcoma cells showed an accumulation of vinculin and F-actin toward the plasma membrane. Interestingly, the phenotype of ETS1-activated Ewing sarcoma cell lines depleted of TNS3 resembled the phenotype of the control cells. Critically, these findings have clinical relevance as TNS3 expression in Ewing sarcoma tumors positively correlates with that of ETS1. Implications: ETS1\'s transcriptional regulation of the gene encoding the focal adhesion protein TENSIN3 in Ewing sarcoma cells promotes cell movement, a critical step in the evolution of metastasis.
摘要：
尤因肉瘤转移的机制基础仍然知之甚少，因为这些肿瘤在引发疾病的染色体易位之外几乎没有突变。相反，尤因肉瘤(EWS)细胞的表观基因组反映了与融合癌蛋白EWSR1::FLI1或EWSR1::ERG的DNA结合活性相关的基因的调节状态.在这项研究中,我们检查了EWSR1::FLI1/ERG对转录因子基因的抑制，集中在那些在肿瘤中比在EWS细胞系中表现出更广泛表达的细胞上。专注于这些目标基因之一，ETS1，我们在该基因座处检测到EWSR1::FLI1结合和H3K27me3抑制标记。EWSR1::FLI1的耗尽导致ETS1与启动子区域的结合，显著改变EWS细胞的转录组，包括编码TENSIN3（TNS3）的基因的上调，粘着斑蛋白.与对照细胞相比,表达ETS1(CRISPRa)的EWS细胞系表现出增加的TNS3表达和增强的运动。对照EWS细胞的可视化显示出分布的Vinculin信号和F-肌动蛋白的网络样组织;相比之下，ETS1激活的EWS细胞显示出黏珠蛋白和F-肌动蛋白向质膜的积累。有趣的是,消除TNS3的ETS1激活的EWS细胞系的表型与对照细胞的表型相似。严重的,这些发现具有临床相关性,因为TNS3在EWS肿瘤中的表达与ETS1的表达呈正相关.含义：ETS1对Ewing肉瘤细胞中编码粘着斑蛋白TENSIN3的基因的转录调节促进细胞运动，转移进化的关键步骤。
