Identification of a novel spliced variant of the SYT gene expressed in normal tissues and in synovial sarcoma

Synovial sarcoma (SS) is cytogenetically characterized by the translocation t(X;18)(p11.2-q11.2) generating a fusion between the SYT gene on chromosom e 18 and one member of the SSX family gene (SSX1; SSX2; SSX4) on chromosome X. Here, we report for the first time that 2 forms of SYT mRNA are present in both normal tissues and SSs. By amplifying the full-length SYT cDNA of two SSs, we detected 2 bands, here designated N-SYT and I-SYT. The latter, previously undescribed, contains an in-frame insertion of 93 bp. Its sequen cing revealed a 100% homology with the mouse SYT gene. These two SYT forms were present, although in different amounts, in all human normal tissues ex amined, including kidney, stomach, lung, colon, liver and synovia. Coexiste nce of N-SYT and I-SYT (both fused with SSX) was detected in a series of 59 SSs (35 monophasic and 24 biphasic) and in a SS cell line. A preliminary a nalysis of the differential expression levels of N-SYT and I-SYT in SSs rev ealed that the latter was consistently overexpressed, suggesting a role in SS pathogenesis. (C) 2001 Cancer Research Campaign.