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: 5.04). 01/1994; 13(12):7393-8. DOI: 10.1128/MCB.13.12.7393
Source: PubMed

ABSTRACT 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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Available from: Michael J Klemsz, Aug 13, 2015
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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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    • "Initial clues about the role of the FET proteins in gene transcription came from the observation that their N-terminal SYGQ-rich domain functions as a potent transcriptional activation domain in oncogenic fusion proteins (Bertolotti et al., 1999; May et al., 1993; Prasad et al., 1994; Zinszner et al., 1994). Moreover, the Drosophila homologue of FUS, named Cabeza (CAZ) or Sarcoma-associated RNA binding fly homologue (SARFH), was found to localize to areas of active transcription in polytene chromosomes of salivary glands (Immanuel et al., 1995). "
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    • "In ES, copy number changes were low in any given tumor sample lending credence to the primary translocation in ES being a single major genetic hit of great import in development and maintenance of tumors. This supports studies on cultured human ES cells in which knockdown of EWS–FLI expression was shown to be sufficient to reverse transformation and tumorigenic properties (May et al., 1993). As stated earlier, however, EWS–FLI1 expression is likely not the only genetic or epigenetic hit that is required for development and maintenance of ES (Lessnick et al., 2002; Castillero-Trejo et al., 2005). "
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