Department of Pathology, Wayne State University, Detroit, MI, USA.
Genes Chromosomes Cancer. 2011 Dec;50(12):1054-62. doi: 10.1002/gcc.20923. Epub 2011 Aug 24.
Cellular morphology of small cell osteosarcoma, an aggressive variant of osteosarcoma, is similar to Ewing sarcoma, but its molecular pathogenesis is largely unknown. We report the case of a 12-year-old girl with multifocal small cell osteosarcoma positive for the Ewing sarcoma breakpoint region 1 (EWSR1) gene rearrangement by interphase fluorescent in situ hybridization and negative for EWSR1-FLI1, EWSR1-ERG, and EWSR1-WT1 fusion transcripts by reverse transcriptase PCR. Rapid amplification of cDNA ends revealed exon 6 of the cAMP-responsive element binding protein 3-like 1 gene (CREB3L1, also known as "OASIS," NM_52854.2) fused in-frame to the EWSR1 exon 11, consistent with the EWSR1-CREB3L1 fusion transcript expressed in tumor tissue. The corresponding chimeric gene was confirmed by amplification and subsequent sequencing of the genomic breakpoint between introns 11 and 5 of EWSR1 and CREB3L1, respectively. An ∼70 kDa product in the tumor tissue lysate reacted with the CREB3L1 carboxyterminal antibody, consistent with a 656-amino acid predicted chimeric protein. Immunohistochemistry with the same antibody showed signal translocation from the physiologic perinuclear compartment observed in glia and unrelated osteoblasts to nuclei of tumor cells, consistent with the likely function of EWSR1-CREB3L1 as a transcriptional regulator predicted by its structure. This is the first report of a fusion transcript in osteogenic sarcoma; it demonstrates a relation between molecular mechanisms of small cell osteogenic and Ewing sarcomas. The 3'-end partner and the inferred structure of EWSR1-CREB3L1, however, are different from those of Ewing sarcoma, suggesting different targets of the new oncogene.
小细胞骨肉瘤是骨肉瘤的一种侵袭性变体，其细胞形态类似于尤因肉瘤，但分子发病机制在很大程度上尚不清楚。我们报告了一例 12 岁女孩的病例，该患者的小细胞骨肉瘤呈多灶性，通过间期荧光原位杂交呈 EWSR1 基因重排阳性，通过逆转录 PCR 呈 EWSR1-FLI1、EWSR1-ERG 和 EWSR1-WT1 融合转录本阴性。快速扩增 cDNA 末端显示 cAMP 反应元件结合蛋白 3 样 1 基因（CREB3L1，也称为“OASIS”，NM_52854.2）的外显子 6 与 EWSR1 的外显子 11 融合，形成框架内融合，与肿瘤组织中表达的 EWSR1-CREB3L1 融合转录本一致。通过分别扩增和随后测序 EWSR1 和 CREB3L1 的内含子 11 和 5 之间的基因组断点，确认了相应的嵌合基因。肿瘤组织裂解物中的约 70 kDa 产物与 CREB3L1 羧基末端抗体反应，与预测的 656 个氨基酸的嵌合蛋白一致。用相同的抗体进行免疫组化染色，发现信号从观察到的胶质细胞和无关成骨细胞的生理核周隔室转移到肿瘤细胞的核内，这与 EWSR1-CREB3L1 作为转录调节剂的可能功能一致，这是由其结构预测的。这是骨肉瘤中融合转录本的首次报告；它证明了小细胞成骨肉瘤和尤因肉瘤之间分子机制的关系。然而，EWSR1-CREB3L1 的 3'-末端伙伴和推断的结构与尤因肉瘤不同，这表明新癌基因的不同靶点。
