The Ewing’s sarcoma EWS/FLI-1 fusion gene encodes a more potent transcriptional activator and is a more powerful transforming gene than FLI-1

Department of Pediatrics, Gwynne Hazen Cherry Memorial Laboratories, University of California, Los Angeles.
Molecular and Cellular Biology (Impact Factor: 4.78). 01/1994; 13(12):7393-8. DOI: 10.1128/MCB.13.12.7393
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EWS/FLI-1 is a chimeric protein formed by a tumor-specific 11;22 translocation found in both Ewing's sarcoma and primitive neuroectodermal tumor of childhood. EWS/FLI-1 has been shown to be a potent transforming gene, suggesting that it plays an important role in the genesis of these human tumors. We now demonstrate that EWS/FLI-1 has the characteristics of an aberrant transcription factor. Subcellular fractionation experiments localized the EWS/FLI-1 protein to the nucleus of primitive neuroectodermal tumor cells. EWS/FLI-1 specifically bound in vitro an ets-2 consensus sequence similarly to normal FLI-1. When coupled to a GAL4 DNA-binding domain, the amino-terminal EWS/FLI-1 region was a much more potent transcriptional activator than the corresponding amino-terminal domain of FLI-1. Finally, EWS/FLI-1 efficiently transformed NIH 3T3 cells, but FLI-1 did not. These data suggest that EWS/FLI-1, functioning as a transcription factor, leads to a phenotype dramatically different from that of cells expressing FLI-1. EWS/FLI-1 could disrupt normal growth and differentiation either by more efficiently activating FLI-1 target genes or by inappropriately modulating genes normally not responsive to FLI-1.

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    • "FLI1 (Friend leukemia virus integration 1, also known as EWSR2) and ERG [v-ets erythroblastosis virus E26 oncogene homolog (avian)] are closely related members of the erythroblast transformation-specific (ETS) family of transcription factors, containing ETS-type DNA-binding domain [15, 16]. The oncogenic fusion proteins preserve the N-terminal EWS domain and ETS domain of FLI1 or ERG, and function as an aberrant transcriptional activator [14, 17, 18]. In the most prevalent fusion variants, EWS exon 7 is fused to FLI1 exon 6 (type 1), FLI1 exon 5 (type 2), or ERG exon 9 [14, 15]. "
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    ABSTRACT: Ewing sarcoma (ES) is a group of highly aggressive small round cell tumors of bone or soft tissue with high metastatic potential and low cure rate. ES tumors are associated with a rapid osteolysis and necrosis. The currently accepted clinical prognostic parameters do not accurately predict survival of high-risk patients. Moreover, neither the subtype of EWS-FLI1/ERG in the tumor, nor the detection of fusion transcripts in the peripheral blood (PB) samples, has prognostic value in ES patients. We evaluated the prevalence of circulating tumor cells (CTCs) in 34 adult ES patients. Since CTCs were confirmed in only small subset of patients, we further explored the expression profiles of PB leukocytes using a panel of genes associated with immune system status and increased tumor invasiveness. Moreover, we analyzed the alterations of the routine blood tests in the examined cohort of patients and correlated our findings with the clinical outcome. A uniform decrease in ZAP70 expression in PB cells among all ES patients, as compared to healthy individuals, was observed. Monocytosis and the abnormal expression of CDH2 and CDT2 genes in the PB cells significantly correlated with poor prognosis in ES patients. Our study supports the previously proposed hypothesis of systemic nature of ES. Based on the PB cell expression profiles, we propose a mechanism by which immune system may be involved in intensification of osteoclastogenesis and disease progression in ES patients. Moreover, we demonstrate the prognostic value of molecular PB testing at the time of routine histopathological diagnosis.
    Medical Oncology 08/2014; 31(8):109. DOI:10.1007/s12032-014-0109-2 · 2.63 Impact Factor
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    • "In the basal state, endogenous EWS interacted weakly with YBX1 (Figure 3A, middle panels), but following short adipogenic stimulation (4h), the EWS-YBX1 interaction was greatly enhanced (Figure 3A, lower panels). EWS encodes a potent transactivation domain in the amino-terminus (May et al., 1993) and is frequently involved in chromosomal translocations that generate aberrant transcription factors (Sankar and Lessnick, 2011). Thus, we tested the effects of EWS on the transcriptional regulation of Bmp7 using a 1395-bp (-1392 to +3) mouse Bmp7 promoterreporter construct that contains an YBX1-binding site in the proximal region (-192 to +3) (Wang and Hirschberg, 2011). "
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    ABSTRACT: The recent surge in obesity has provided an impetus to better understand the mechanisms of adipogenesis, particularly in brown adipose tissue (BAT) because of its potential utilization for antiobesity therapy. Postnatal brown adipocytes arise from early muscle progenitors, but how brown fat lineage is determined is not completely understood. Here, we show that a multifunctional protein, Ewing Sarcoma (EWS), is essential for determining brown fat lineage during development. BATs from Ews null embryos and newborns are developmentally arrested. Ews mutant brown preadipocytes fail to differentiate due to loss of Bmp7 expression, a critical early brown adipogenic factor. We demonstrate that EWS, along with its binding partner Y-box binding protein 1 (YBX1), activates Bmp7 transcription. Depletion of either Ews or Ybx1 leads to loss of Bmp7 expression and brown adipogenesis. Remarkably, Ews null BATs and brown preadipocytes ectopically express myogenic genes. These results demonstrate that EWS is essential for early brown fat lineage determination.
    Developmental Cell 08/2013; 26(4):393-404. DOI:10.1016/j.devcel.2013.07.002 · 9.71 Impact Factor
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    • "EWS and FUS, also classified into hnRNP family, are two members of FET family of protooncoproteins, consisting of C-terminal RNA-binding domain and N-terminal transcriptional activation domain [69–71]. C-terminal region that contains RRMs, RGG repeats, and zinc finger domain of these two proteins is responsible for their interactions with RNA and ssDNA, while N-terminal has SYGQQS repeats behaving as transcription activator that is essential in transforming activity of oncogenic fusion proteins derived from translocation of EWS or FUS with ETS family of transcription factors such as FLI1 and ERG [61, 72–74]. Endogenous EWS is indispensable for stem cell quiescence and maintenance as depletion of EWS gene promotes early cellular senescence in hematopoietic stem/progenitor cells [62]. "
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    ABSTRACT: Stem cells possess huge importance in developmental biology, disease modelling, cell replacement therapy, and tissue engineering in regenerative medicine because they have the remarkable potential for self-renewal and to differentiate into almost all the cell types in the human body. Elucidation of molecular mechanisms regulating stem cell potency and differentiation is essential and critical for extensive application. Heterogeneous nuclear ribonucleoproteins (hnRNPs) are modular proteins consisting of RNA-binding motifs and auxiliary domains characterized by extensive and divergent functions in nucleic acid metabolism. Multiple roles of hnRNPs in transcriptional and posttranscriptional regulation enable them to be effective gene expression regulators. More recent findings show that hnRNP proteins are crucial factors implicated in maintenance of stem cell self-renewal and pluripotency and cell differentiation. The hnRNPs interact with certain sequences in target gene promoter regions to initiate transcription. In addition, they recognize 3'UTR or 5'UTR of specific gene mRNA forming mRNP complex to regulate mRNA stability and translation. Both of these regulatory pathways lead to modulation of gene expression that is associated with stem cell proliferation, cell cycle control, pluripotency, and committed differentiation.
    07/2013; 2013(1):623978. DOI:10.1155/2013/623978
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