Apart from the canonical SS18-SSX fusion, this is only the second alternative gene fusion variant described in synovial sarcoma to date, in addition to two cases harboring the SS18L1-SSX1 fusion.
Meta-analyses showed that the test of detecting MDM2 amplification by fluorescence in situ hybridization was accurate in differentiating atypical lipomatous tumor/well-differentiated liposarcoma/dedifferentiated liposarcoma from benign tumors (N = 971; sensitivity = 95%, 95% confidence interval [CI] 89-98; specificity = 100%, CI 89-100) or from other STS (N = 347; sensitivity = 99%, CI 72-100; specificity = 90%, CI 78-95); that the test of detecting SS18-SSX fusion by reverse transcription polymerase chain reaction (PCR) was accurate in differentiating synovial sarcoma from other STS (N = 532; sensitivity = 93%, CI 85-96; specificity = 99%, CI 96-100).
Synovial sarcoma is an aggressive cancer invariably associated with a chromosomal translocation involving genes encoding the SWI-SNF complex component SS18 and an SSX (SSX1 or SSX2) transcriptional repressor.
Isobaric tags for relative and absolute quantitation (i-TRAQ) analyses identified approximate 1700-2,000 proteins regulated by the SS18/SSX fusion in each SS cell line.
Additionally, we showed that SS can originate from periosteal cells expressing SS18-SSX alone and from preosteoblasts expressing the fusion oncogene accompanied by the added stabilization of β-catenin, which is a common secondary change in SS.
Synovial sarcoma (SS) is characterized by a tumour specific chromosomal translocation t(X;18) (p11;q11) which results in the formation of SYT-SSX1 fusion protein.
Our analyses revealed that the primary tumor and NCC-SS1-C1 cell line harbored the SS18-SSX1 fusion gene typical of synovial sarcoma and similar proteomics profiles.
A transbronchial biopsy was performed, and immunohistochemical results as well as detection of SYT-SSX1 (SYnovial sarcoma Translocation-Synovial Sarcoma X chromosome breakpoint) transcripts resulted in a diagnosis of synovial sarcoma.
This review summarises our current understanding of the function of SS18-SSX and the mechanisms by which it alters the epigenetic landscape of permissive cells to induce transformation and the subsequent development of synovial sarcoma.
We demonstrate that BRD9 supports oncogenic mechanisms underlying the SS18-SSX fusion in synovial sarcoma and highlight targeted degradation of BRD9 as a potential therapeutic opportunity in this disease.
Here we demonstrate that SS18-SSX globally hijacks BAF complexes on chromatin to activate an SS transcriptional signature that we define using primary tumors and cell lines.
Based on our results, neither histological grading nor SYT-SSX fusion status seems to be suitable for outcome prediction and risk stratification in localized SS treated according to the CWS.
The aim of this study was to verify whether histological (grading and histology) and molecular (type of SSX translocation and INI1 expression) characteristics of SS influence the prognosis of the disease.