ANALYSIS OF FUS-CHOP FUSION TRANSCRIPTS IN DIFFERENT TYPES OF SOFT-TISSUE LIPOSARCOMA AND THEIR DIAGNOSTIC IMPLICATIONS

In myxoid and round cell liposarcomas, a specific chromosomal transloc ation [(12;16)(q13;p11)] results in the expression of chimeric fusion transcripts encompassing parts of the FUS gene (16p11) at their 5' end s and the CHOP gene (12q13) at their 3' ends. Using a reverse transcri ption-PCR protocol, we determined the prevalence of FUS-CHOP fusion tr anscripts in a series of liposarcoma samples. Fusion transcripts were detected in 13 of 30 biopsy samples from soft tissue liposarcomas. Exp ression of fusion transcripts was not restricted to myxoid and round c ell liposarcomas, as suggested previously; it was also detected in 1 o f 3 well-differentiated and 4 of 14 pleomorphic liposarcomas. Sequence analysis revealed four different FUS-CHOP fusion transcript variants, two of which have not been described before. Furthermore, using FUS-C HOP fusion transcripts as targets in reverse transcription-PCR assays, we detected disseminated tumor cells in peripheral blood or bone marr ow in 3 of 5 patients undergoing surgery for soft tissue liposarcoma.