First cloned human immortalized adipose derived mesenchymal stem-cell line with chimeric SS18-SSX1 gene (SS-iASC).

The SS18-SSX chimeric gene is unique to synovial sarcoma. Multiple model systems including mouse cell lines expressing SS18-SSX, and genetically engineered mouse models of synovial sarcoma have been developed to elucidate the role of the chimeric gene in synovial sarcomagenesis. Although several cell lines stably expressing human SS18-SSX exist, there is an ongoing need for cell culture models enabling researchers to investigate the molecular mechanism of SS18-SSX action in a relevant cellular context. Here we report the establishment of a novel SS18-SSX1-expressing cell line created from immortalized human adipose tissue-derived mesenchymal stem cells via lentiviral transduction of the chimeric gene. Our cell line, termed SS-iASC, has been characterized by karyotyping and cell line identification, and stable expression of SS18-SSX1 has been verified using real-time PCR (RT-PCR), nested PCR, immunofluorescence, and immunoblotting. Focal cytokeratin positivity characteristic of synovial sarcoma but no β-Catenin, Bcl-2 or cyclin D1 expression was observed in SS-iASC. The novel cell line expressing SS18-SSX1 on a human adipose-derived stromal cell background is expected to be helpful in addressing the question whether the chimeric gene alone is sufficient to trigger the formation of synovial sarcoma.