Expression of DOL54 is not restricted to myxoid liposarcomas with the FUS-DDIT3 chimera but is found in various sarcomas

The DOL54 gene [also known as megakaryocyte stimulating factor, articular superficial zone protein (SZP) or proteoglycan 4 (PRG4)], was cloned as a downstream target gene of the FUS-DDIT3 chimera, which is the fusion gene that characterizes myxoid liposarcoma (MLS). Activation of DOL54 was found to require an intact DNA binding domain of the DDIT3 protein and to be dependent on the presence of the N-terminal part of the FUS protein. Although originally suggested to be of oncogenic significance, expression analysis of DOL54 in tumors has so far been limited to a few cases of liposarcoma and malignant fibrous histiocytoma (MFH). In the present study we were interested to evaluate whether DOL54 expression can be associated with other fusion genes in which FUS is the 5'-partner. Thus, we investigated the expression of DOL54 in low grade fibromyxoid sarcoma (LGFMS) carrying the FUS-BBF2H7 chimeric transcript. We also included synovial sarcomas (SS), Ewing tumors (ET), extraskeletal myxoid chondrosarcomas (EMC) and MFH. The first 3 of these tumor types are characterized by chromosomal translocations that give rise to fusion genes not involving FUS, while no specific chimeric genes have been reported in MFH. DOL54 expression was found in 8/12 LGFMS carrying the FUS-BBF2H7 chimera but also in 8/10 of the examined MFH, 5/7 SS, 2/5 ET and 7/7 examined EMC. The results of our study clearly show that expression of DOL54 is not only a characteristic feature of MLS with the FUS-DDIT3 chimera but that this is a frequent finding also in various other sarcomas.