Klin Padiatr 2010; 222 - A16
DOI: 10.1055/s-0030-1254467

Characterization of EWS-FLI1 fusion sites in Ewing sarcomas

M Berger 1, M Krumbholz 1, U Dirksen 2, A Braeuninger 3, M Metzler 1
  • 1Department of Pediatrics, University of Erlangen, Erlangen, Germany
  • 2Department of Pediatric Hematology and Oncology, University of Muenster, Muenster, Germany
  • 3Department of Molecular Pathology, University of Muenster, Muenster, Germany

Aims: Chromosomal translocations are recurrent somatic aberrations in hematologic and mesenchymal malignancies. Genomic breakpoints have been analyzed in a number of leukemia subtypes in order to deduce mechanism involved in translocation formation from DNA fusion sequences. Only few translocation fusion sites have sequenced in sarcomas. Here we show a powerful tool to detect the genomic EWS-FLI1 breakpoint, resulting from t(11;22)(q24;q12), the most common chromosomal translocation in Ewing Sarcomas (ES).

Patients and method: Using a two round multiplex long-range PCR (MLR-PCR) EWS-FLI1 fusion sites were amplified from tumour tissue DNA of 38 paediatric ES patients and 8 ES cell lines.

Results: MLR-PCR successfully amplified patient and cell line specific fusion sites in all tested DNA samples. There are no breakpoint subclusters within the Breakpoint Cluster Region (BCR) of FLI1, in contrast to a clustering in the 5′ region of the EWS-BCR. We could not identify association of breakpoints to various recombination inducing sequence motifs.

Conclusion: In comparison to previous results from breakpoint analyzes in different leukemia subtypes, distribution and breakpoint fine structure suggest a similar underlying mechanism of breakpoint repair in ES. The patient specific genomic fusion site also represents an individual molecular marker for absolute tumor cell quantification in diagnostic and follow up specimen.