Gene expression profiles relate to SS18/SSX fusion type in synovial sarcoma

Abstract

We applied 27k spotted cDNA microarray slides to assess gene expression profiles in 26 samples from 24 patients with synovial sarcomas (SS). The data were analyzed in relation to histopathologic type, cytogenetic aberrations, gene fusion type and development of distant metastases. Supervised analysis based on gene fusion type in 12 SS with SS18/SSX1 and 9 with SS18/SSX2 revealed significant differences in gene expression profiles. Among the discriminators were several genes that have previously been found to be upregulated in SS, including AXL, ZIC2, SPAG7, AGRN, FOXC1, NCAM1 and multiple metallothioneins. Histopathology and degree of cytogenetic complexity did not significantly influence expression, whereas a genetic signature that related to development of metastases could be discerned, albeit with a high false‐positive rate. In conclusion, our findings demonstrate differentially expressed genes for the 2 major gene fusion variants in SS, SS18/SSX1 and SS18/SSX2, and thereby suggest that these result in different downstream effects.