Detection of chimeric genes in Ewing's sarcoma and its clinical applications

Ewing's sarcoma (ES), most commonly an undifferentiated tumor of bone, belongs to the enigmatic diagnostic category of small round cell tumors (SRCT) of childhood. The consistent presence of the translocation t (11; 22) in the vast majority of tumors provides evidence for a common histogenesis in ES and its family of tumors (ESFT), and also provides a unique diagnostic characteristic to discriminate this tumor family from SRCT. Molecular analysis of this translocation has revealed that it forms a chimeric gene between EWS on chromosome 22 and FLI-1 on chromosome 11. Similarly, the variant t (21; 22), t (7; 22), t (17; 22), and t (2; 22) rearrangements also form chimeric genes between regions of EWS and the ETS gene family (ERG, ETV1, E1AF, and FEV). Detection of these specific chimeric genes would provide a method for diagnosis of ESFT. We have developed a procedure for simultaneous detection of the chimeric genes by reverse transcription polymerase chain reaction (RT-PCR) with a mixture of primers. We conclude that the detecting those chimeric genes by this method can be easy and useful for diagnosis of ESFT. Moreover, by defining the specific chimeric gene it is possible to detect the tumor cell contamination in autologous blood stem cell transplantation.