Transformation induced by Ewing's sarcoma associated EWS/FLI-1 is suppressed by KRAB/FLI-1.
Ewing's sarcoma is a childhood bone tumour with poor prognosis, most commonly associated with a t(11;22)(q24;q12) reciprocal translocation that fuses the EWS and FLI-1 genes, resulting in the production of an aberrant chimeric transcription factor EWS/FLI-1. To elucidate the mechanisms by which EWS/FLI-1 mediates transformation in mouse models, we have generated a murine Ews/Fli-1 fusion protein. We demonstrate that this protein transforms fibroblast cells in vitro similar to human EWS/FLI-1 as demonstrated by serum and anchorage-independent growth, the formation of tumours in nude mice and elevation of the oncogenic marker c-myc. Furthermore, transformation of these cells was inhibited by a specific repressor, KRAB/FLI-1. The KRAB/FLI-1 repressor also suppressed the tumorigenic phenotype of a human Ewing's sarcoma cell line. These findings suggest that the transformed phenotype of Ewing's sarcoma cells can be reversed by using the sequence-specific FLI-1-DNA-binding domain to target a gene repressor domain. The inhibition of EWS/FLI-1 is the first demonstration of the KRAB domain suppressing the action of an ETS factor. This approach provides potential avenues for the elucidation of the biological mechanisms of EWS/FLI-1 oncogenesis and the development of novel therapeutic strategies.
Chan
D
D
Centre for Functional Genomics and Human Diseases, Monash Institute of Reproduction and Development, Monash University, Melbourne, Australia.
Wilson
T J
TJ
Xu
D
D
Cowdery
H E
HE
Sanij
E
E
Hertzog
P J
PJ
Kola
I
I
D016475:3T3 Cells; D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002471:Cell Transformation, Neoplastic / Q000139:chemically induced*; D003114:Colony-Forming Units Assay; D003470:Culture Media; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology*; D016153:Genes, Suppressor / Q000502:physiology; D051379:Mice; D010641:Phenotype; D017434:Protein Structure, Tertiary; D051789:Proto-Oncogene Protein c-fli-1; D011518:Proto-Oncogene Proteins; D034802:RNA-Binding Protein EWS / Q000235:genetics / Q000494:pharmacology*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000494:pharmacology; D012097:Repressor Proteins; D012512:Sarcoma, Ewing / Q000737:chemistry*; D015534:Trans-Activators / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology*
D003470:Culture Media; D004268:DNA-Binding Proteins; C497426:Fli1 protein, mouse; D051789:Proto-Oncogene Protein c-fli-1; D011518:Proto-Oncogene Proteins; D034802:RNA-Binding Protein EWS; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D015534:Trans-Activators; C422407:ZNF350 protein, human