Fusion of the RBP56 and CHN Genes in Extraskeletal Myxoid Chondrosarcomas with Translocation T(9;17)(q22;q11)

Although most extraskeletal myxoid chondrosarcomas (EMC) are cytogenetically characterized by the translocation t(9;22)(q22;q12), another subset has recently been identified carrying a t(9;17)(q22;q11). Whereas the t(9;22) is known to result in fusion of the CHN (TEC) gene from 9q22 with the EWS gene from 22q12, creating a chimeric EWS/CHN, the genes involved in the t(9;17) of EMC are unknown. We examined two EMC with t(9;17)(q22;q11) and found that the CHN gene was recombined with the RBP56 gene from 17q11 to generate a chimeric RBP56/CHN. RBP56 has not previously been shown to be involved in tumorigenesis but it encodes a putative RNA-binding protein similar to the EWS and FUS (TLS) proteins known to play a pathogenetic role in several sarcomas. The presence of the RBP56/CHN chimeric gene in EMC with t(9;17)(q22;q11) shows that the N-terminal parts of EWS and RBP56 have similar oncogenic potential making them pathogenetically equivalent in oncoproteins arising from fusions with certain transcription factors.