2130

EWSR1

EWS|bK984G1.4;Ewing sarcoma breakpoint region 1;EWSR1;Ewing sarcoma breakpoint region 1

Ewings sarcoma EWS-Fli1 (type 1) oncogene|RNA-binding protein EWS

22q12.2

protein-coding

A 14-year-old boy presented with a soft tissue swelling on the outer aspect of his left upper arm. Examination of the tumor by light microscopy showed a small round cell tumor with a rare focus of myogenic differentiation. Myogenic differentiation was confirmed on ultrastructural examination by immunohistochemistry and reverse transcriptase polymerase chain reaction (RT-PCR). Conventional G-banding and fluorescent in situ hybridization (FISH) demonstrated a complex variant of t(21;22)(q22;q12). By RT-PCR, the EWS-ERG fusion transcript was defined as type 9e. This tumor was unusual in that it showed characteristics of myogenic and neural differentiation, and contained a rearrangement of the EWS gene consistent with a diagnosis of Ewing's sarcoma. This supports the hypothesis that a class of biphenotypic childhood sarcomas, with features of myogenic and neural differentiation, exists that may be relatedto the Ewing's sarcoma family of tumors.

Ewing sarcoma-primitive neuroectodermal tumor (EWS/PNET) belongs to the group ofpediatric small round blue cell tumors; although EWS/PNET is classically a tumorof the soft tissue or bone in children and young adults, individual cases have been described in patients of ALL ages. A group of chromosomal translocations involving the EWS gene and a member of the Ets transcription factor family of genes has been detected in EWS/PNET, and heterogeneity in the precise breakpointof the translocation has been shown to generate a group of related fusion transcripts that may have prognostic significance. Within the last decade, the clinicopathologic spectrum of EWS/PNET has been markedly expanded by recognitionthat the tumor may also have a visceral origin. To determine whether visceral EWS/PNET has the same pattern of genetic alterations and range of fusion transcripts as EWS/PNET of bone and soft tissue, we performed reverse-transcription polymerase chain reaction-based testing of formalin-fixed,paraffin-embedded tissue from a series of visceral tumors for which the diagnosis of EWS/PNET was well established. Together with additional cases compiled from the literature, EWS-Fli1 (or a related fusion transcript) was present in 18 of 19 visceral EWS/PNET, with a distribution of transcript types not statistically different from EWS/PNET of soft tissue and bone (P >.05, chi(2) test). These results firmly establish the genetic relationship between EWS/PNET of visceral sites, soft tissue, and bone.#CI- Copyright 2001 by W.B. Saunders Company

Ewing's sarcoma is the second most common primary bone tumor seen in children and adolescents, and was described by James Ewing in 1921 as a diffuse endothelioma of bone. It is one of the differential diagnoses of pediatric small round blue cell tumors. This is not a single condition, but a group of morphologically and clinically closely related disorders with similar molecular biology -- expression of tumor-specific chimeric oncoproteins through balanced chromosomal translocations involving the EWS gene -- often referred to as the Ewing family of tumors. This includes Ewing's sarcoma of bone, extra-osseous Ewing's sarcoma, Askin tumor and peripheral neuroectodermal tumor. These are aggressive neoplasmswith almost 25% of patients having clinically evident metastases at presentation. Ewing's sarcoma has therefore been considered as a systemic disease necessitating local as well as systemic treatment. An aggressive multidisciplinary approach has resulted in significant improvement in prognosis for patients with these tumors.Despite aggressive treatment, 20-40% of patients with localized disease and almost 80% of patients with metastatic disease at presentation succumb to the illness. Advances in understanding the molecular biology of these tumors will hopefully result in the development of novel treatment approaches. The aim of this article is to review the existing treatment methods and to highlight the more recent approaches to the treatment of this condition.

BACKGROUND: Ewing sarcoma is a malignant bone tumor characterized by a high frequency of somatic EWSR1 translocations. Ewing sarcoma is less common in people of African or African-American ancestry, suggesting a genetic etiology. PROCEDURE: Germline DNA from white patients with Ewing sarcoma (n = 135), white controls with Wilms tumor (n = 200), and African-American controls (n = 285) wasgenotyped at 21 SNPs in the EWSR1 gene. Intron 7 of EWSR1, the most common site of translocation, was also sequenced in ALL subjects. Genetic variation between groups was evaluated statistically using exact logistic regression and Fisher exact tests. RESULTS: One SNP in EWSR1 (rs2857461) showed a low level of statistical association with the diagnosis of Ewing sarcoma compared to Wilms tumor. The odds ratio for having Ewing sarcoma in people with at least one copy of the minor allele of rs2857461 was 3.57 (95% confidence interval 0.79-21.7; P = 0.07). No other SNPs or variations in intron 7 of EWSR1 were associated with Ewing sarcoma. The median relative difference in minor allele frequencies between white subjects with Ewing sarcoma and African-American controls at the evaluatedEWSR1 SNPs was 45%. CONCLUSIONS: Variations in EWSR1 at known SNPs or across intron 7 are not associated with the diagnosis of Ewing sarcoma. EWSR1 does not appear to be an Ewing sarcoma susceptibility gene. The genetic basis for this disease remains unknown.#CI- Copyright (c) 2011 Wiley Periodicals, Inc.

Ewing sarcoma, a rare malignancy of childhood and adolescence, has attracted wide research interest. tumor-specific chromosomal translocations generate aberrant EWS-ETS transcription factors, which alter intracellular signaling networks through gene and protein expression and are considered to be the primary tumor-initiating event. Ewing sarcoma therefore offers insights into principle molecular mechanisms of cancer development and maintenance. Still, despite long-standing research, biology-based targeted treatment strategies for Ewing sarcoma are only beginning to emerge. This article provides an overview of the biological basis and putative targeted treatment options.

There are major differences between tumors in children and adults, viz. the incidence of tumor types, the predisposition of certain organs and tissues (e.g.sympathetic nervous tissue, kidney, and soft tissues) to develop tumors, problems related to tumor classification, and the biologic behavior of childhood malignancies, which are usually characterized by high rates of proliferation activity. A large number of new entities, especially in soft tissue tumors, havebeen published over the past years, including nodular mesothelial hyperplasia, which is a tumor-like lesion derived from peritoneal macrophages; infantile myofibromatosis, which can mimic leiomyosarcoma; intermediate grade fibrohistiocytic tumors, like dermatofibrosarcoma protuberans-related giant-cellfibroblastoma, plexiform fibrohistiocytic tumor and angiomatoid malignant fibrous histiocytoma displaying evidence of myogeneous differentiation; finally, the high-grade intraabdominal desmoplastic small cell tumor. With modern methods we can gain better insights into the biology of tumors. For example, tumors of the Ewing's sarcoma family have in common a characteristic t(11; 22) chromosomal translocation, the Ewing's sarcoma (EWS) (22q12) gene rearrangement, and the MIC2 gene. The EWS gene rearrangement is not restricted to tumors of the Ewing's sarcoma family (classic Ewing's sarcoma and malignant peripheral neuroectodermaltumor), however, but occurs in malignant melanoma of the soft tissue and in intraabdominal desmoplastic small cell tumor. Rhabdomyosarcomas (RMS) can be divided into two basic types with different prognoses: embryonal RMS, including botryoid and spindle-cell variants, and alveolar RMS, including the solid variant. The prognosis of alveolar RMS is poorer than that of classic embryonal RMS, mainly due to early tumor dissemination in alveolar RMS. The prognosis of neuroblastoma is mainly based on chromosomal and molecular biologic findings. Structural chromosome 1 abnormalities, double minute chromosomes, homogeneously staining regions, N-myc amplifications, and DNA diploidy are indications for an unfavorable outcome. Despite progress in childhood solid tumor pathology, many questions remain open, including those relating to basic chromosomal defects in germ cell tumors and the obscure nature of tumor heterogeneity.