Platelet-derived exosomes promote the epithelial–mesenchymal transition in MCF7 cells

Breast cancer is a common female malignancy. In recent years, the incidence of breast cancer has increased and has become much younger. Studies have shown that platelet-derived exosomes play an important role in the progression of cancer. In this study, we investigated the effect of platelet-derived exosomes on the epithelial–mesenchymal transition (EMT), migration, and invasion of breast cancer cells. Activated and unactivated platelet-derived exosomes were extracted by ultracentrifugation. The morphology of platelet exosomes was observed and identified by transmission electron microscopy and western blotting. After MCF7 cells are treated with platelet or exosomes, the mRNA and protein levels of EMT-related genes were detected by RT-PCR and western blotting, respectively, and the migration and invasion abilities of MCF7 cells were also observed by transwell. We observed some exosomes-like structures derived from activated platelets by transmission electron microscopy. The level of transforming growth factor-β in activated platelet-derived exosomes was higher than that in unactivated platelet-derived exosomes. After activated platelet or activated platelet-derived exosomes were co-cultured with MCF7 cells, the expression of Snai1, N-cadherin, Vimentin and Fibronectin in activated platelets and breast cancer cells was significantly increased, while the expression of E-cadherin was significantly decreased. Activated platelets and activated platelet-derived exosomes significantly promoted the migration and invasiveness of MCF7 cells. These findings revealed that activated platelet or activated platelet-derived exosome enhances migration and invasion by promoting EMT in MCF cells. In conclusion, platelet-derived exosomes initiate EMT and promote the migration and invasiveness of MCF7 cells.