SYT-SSX fusion proteins in synovial sarcomas: detection and characterization with new antibodies

To identify and characterize the SYT-SSX fusion proteins in synovial sarcom as, we developed two polyclonal antibodies against the N-terminal part and for the C-terminal part of the SYT-SSX2 protein. Specificity was demonstrat ed on COS-7 cells transfected with two subtypes of SYT-SSX fusion genes, SY T-SSX1 and SYT-SSX2. Both antibodies recognized a single protein of 61 kDa in an immunoprecipitation of the transfected COS-7 cell lysates. These anti bodies also detected the native protein of 61 kDa in the lysate of a human synovial sarcoma cell line (HS-SY41) with immunoprecipitation, and in extra cts of human synovial sarcomas with western blot analysis. An immunohistoch emical study, using human synovial sarcoma tissues, demonstrated that the S YT-SSX fusion proteins localized in the nucleus of the tumor cells. These a ntibodies provide a useful method for studying the expression of the SYT-SS X fusion proteins. (C) 2000 Elsevier Science Ireland Ltd. All rights reserv ed.