The t( I I ;22)(q24;q 12) and t(2 I ;22)(q22;q 12) are specific chromosomal translocations found in the Ewing family of tumors including ES, PNET and Askin tumors. In these translocations, the amino-terminal portion of the EWS gene located in 22q12 fuses to the carboxyl-terminal portion of the FLI-I gene located in I lq24 or the ERG gene located in 2 1922, which belong to the ets oncogene superfamily of transcription activators. We investigated the chimeric mRNAs of I 5 ESs (7 cell lines and 8 tumor samples) and 7 PNETs (3 cell lines and 4 tumor samples) using the RT-PCR method and sequencing. We detected 2 types of EWS-ERG chimeric mRNA in 2 ES cell lines and I PNET tumor sample in addition to 4 types of EWS-FLI-I chimeric mRNA in I I ESs (4 cell lines and 7 tumor samples) and 4 PNETs (2 cell lines and 2 tumor samples). There seemed to be no association between the type of chimeric mRNA and clinical features such as sex, age, primary site and histopathology of the patients. All of the chimeric mRNAs are generated from in-frame junctions and are thought to encode fusion proteins that may be the molecular mechanism involved in the Ewing family of tumors. o 1995 Wiley-Liss, lnc.
Ewing's sarcoma (ES) is a highly malignant, small-roundcell sarcoma that occurs mainly in children and young adults, and accounts for approximately 30% of primary bone tumors in this age group . Although lacking any morphological characteristics in many cases, E S cells sometimes express neural differentiation . In this sense, ES cells resemble primitive neuroectodermal tumor (PNET) cells. Increasing evidence, as shown below, suggests that these tumors have a common neural-crest origin but may exhibit variable neural differentiation and tissue localization.
Askin tumor, a small-round-cell sarcoma of the chest wall, is