Identification of EWS/FLI-1 transcripts in giant-cell tumor of bone

The EWS/FLI-1 fusion gene, resulting from a t(11;22) translocation, plays a key role in the pathogenesis of Ewing's sarcoma. We demonstrate the presence of EWS/FLI-1 hybrid transcripts also in giant-cell tumor, a bone neoplasm featuring intermediate characteristics between benign and malignant lesions. Chimeric products were detected by semi-nested PCR after 2 cycles of amplification in 13/15 cases of giant-cell tumor, and their presence was confirmed by Southern and Western blots and fluorescence in situ hybridization. Moreover, 3/8 primary cultures of giant-cell tumor showed the same type of hybrid transcript observed in the original tumor sample. Sequencing of PCR products confirmed the presence of EWS and FLI-1 sequences in these products. Detection of EWS/FLI-1 fusion transcripts in giant-cell tumor of bone provides a model for the study of the transforming mechanisms of the EWS/FLI-1 fusion gene in mesenchymal tumors.