However, there is significant morphologic heterogeneity and overlap with a variety of other neoplasms, which can cause diagnostic challenge, particularly as the immunoprofile is varied, SS18-SSX is not detected in 100% of SSs, and they may occur at unusual sites.
Analysis by reverse transcriptase polymerase chain reaction (RT-PCR) failed to identify the SYT-SSX1 or SYT-SSX2 fusion transcripts characteristic of synovial sarcoma.
In summary, SS18-SSX-induced Wnt/β-catenin signaling appears to be of crucial biological importance in synovial sarcoma tumorigenesis and progression, representing a potential molecular target for the development of novel therapeutic strategies.
Our objective was to evaluate the expression of apoptotic pathway members in synovial sarcomas and interrogate the impact of modulating SS18-SSX expression on this pathway.
These studies reveal the central role of Wnt/β-catenin signaling in SYT-SSX2-induced sarcoma genesis, and open new venues for the development of effective synovial sarcoma curative agents.
Our new FISH assay has several advantages, including its applicability to paraffin-embedded samples, discrimination of the SS18-SSX1 and SS18-SSX2 translocations particularly in cases with aneuploidy, and potentially detecting translocations in all cases of synovial sarcoma, even with variant translocations.
To investigate the underlying mechanism, we studied human synovial sarcoma (SS), in which transformation results from the translocation of exactly 78 amino acids of SSX to the SS18 subunit of BAF complexes.
Although precise function of SYT-SSX remains to be investigated, accumulating evidences suggest its role in gene regulation via epigenetic mechanisms, and the product of SYT-SSX target genes may serve as biomarkers of SS.
The synovial sarcoma (SS)-associated protein, SYT-SSX2, reprograms myogenic progenitors and human bone marrow-derived mesenchymal stem cells (BMMSCs) by dictating their commitment to a pro-neural lineage.
This is the first reported case of a remarkable soft tissue sarcoma that exhibits overlapping morphologic features between SS and EMC and that also harbors a combination of SS18-SSX2 and EWS-NR4A3 gene fusions.
This study may be valuable for understanding the pathogenic role and molecular mechanism of the fusion gene SYT-SSX in synovial sarcoma through the proposed genome-wide approach.
Collectively, these data suggest that a human multipotent mesenchymal stem cell can serve as a cell of origin for SS and SS is a stem cell malignancy resulting from dysregulation of self-renewal and differentiation capacities driven by SS18-SSX fusion protein.
Synovial sarcoma (SS) is an aggressive soft-tissue malignancy characterized by a unique t(X;18) translocation resulting in expression of SS18-SSX fusion protein.
Prospectively, FNAs positive for the SYT-SSX fusion transcript by RT-PCR (n = 6) and, retrospectively, cases proven on histopathology and immunohistochemistry (ICC; positivity for vimentin and epithelial membrane antigen [EMA]/cytokeratin) as SS (n = 10) were included in the study.