Transforming growth factor-β1 signaling promotes epithelial-mesenchymal transition-like phenomena, cell motility, and cell invasion in synovial sarcoma cells.

The epithelial-to-mesenchymal transition (EMT) and the reverse process (the mesenchymal-to-epithelial transition [MET]) have been shown to be associated with tumor cell invasion and metastasis in different carcinomas. The EMT and MET have recently been shown to play a key role in the pathogenic processes of sarcomas, which are completely different from those of carcinomas. However, the definitive roles of the EMT in the tumorigenesis of synovial sarcomas remain unknown. Here, we explored whether transforming growth factor (TGF)-β signaling, an important oncogenic event in synovial sarcoma, modulates tumor cell characteristics related to the EMT, such as cell adhesion, migration, invasion, and proliferation. Interestingly, we found that TGF-β1 induced tumor cell activation, resulting in a tendency to aggregate and biphasic-like features. TGF-β1 also caused downregulation of E-cadherin and subsequent upregulation of N-cadherin, Snail, and Slug, which are responsible for EMT-like phenomena and increased cell motility and invasion. To further investigate the roles of TGF-β1 in the EMT, we established a SW982 cell line with stable TGF-β1 inhibition viaSB431542.These cells exhibited significantly decreased motility, migration, and proliferation (P = 0.001). Taken together, our data demonstrated that alterations in the TGF-β1/Smad signaling pathway could regulate the expression of EMT-related factors and the EMT process, resulting in changes in tumor cell invasion, migration, and proliferation in synovial sarcoma cells. These results may provide a important insights into therapeutic interventions and contribute to the present understanding of tumor progression in patients.