Ewing肉瘤（EwS）是一种罕见的由染色体易位编码嵌合转录因子（如EWSR1-FLI1）驱动的骨和软组织恶性肿瘤，它们结合GGAA模体形成新的增强子改变附近表达。我们提出，在6p25.1的EwS易感位点的种系微卫星变异可能影响下游基因表达和EwS生物学。我们对EwS血液DNA进行有针对性的长读测序，以表征重要的EWSR1-FLI1结合的变异和基因组特征。我们在6p25.1鉴定了50个微卫星等位基因，并观察到EwS-患者具有更长的等位基因（> 135 bp），并且带有更多的GGAA重复序列。6p25.1的GGAA微卫星表现出EWSR1-FLI1增强子的染色质特征，调节与RAS / MAPK信号通路相关的转录因子RREB1的表达。RREB1的knockdown减少了增殖和克隆能力，并减少了细胞周期和DNA复制基因的表达。我们在6p25.1的综合分析详细描述了较长的GGAA微卫星等位基因与获得性EWSR-FLI1增强结合，通过RREB1介导的增殖促进Ewing肉瘤发生。由Elsevier Inc.发表。

Ewing sarcoma (EwS) is a rare bone and soft tissue malignancy driven by chromosomal translocations encoding chimeric transcription factors, such as EWSR1-FLI1, that bind GGAA motifs forming novel enhancers that alter nearby expression. We propose that germline microsatellite variation at the 6p25.1 EwS susceptibility locus could impact downstream gene expression and EwS biology. We performed targeted long-read sequencing of EwS blood DNA to characterize variation and genomic features important for EWSR1-FLI1 binding. We identified 50 microsatellite alleles at 6p25.1 and observed that EwS-affected individuals had longer alleles (>135 bp) with more GGAA repeats. The 6p25.1 GGAA microsatellite showed chromatin features of an EWSR1-FLI1 enhancer and regulated expression of RREB1, a transcription factor associated with RAS/MAPK signaling. RREB1 knockdown reduced proliferation and clonogenic potential and reduced expression of cell cycle and DNA replication genes. Our integrative analysis at 6p25.1 details increased binding of longer GGAA microsatellite alleles with acquired EWSR-FLI1 to promote Ewing sarcomagenesis by RREB1-mediated proliferation.Published by Elsevier Inc.