Mesenchymal stem cell-derived exosomes facilitate nasopharyngeal carcinoma progression

Mesenchymal stem cells (MSCs), which are capable of differentiating into multiple cell types, are reported to exert multiple effects on tumor development. However, the relationship between MSCs and nasopharyngeal carcinoma (NPC) cells remains unclear. Exosomes are small membrane vesicles that can be released by several cell types, including MSCs. Exosomes, which can carry membrane and cytoplasmic constituents, have been described as participants in a novel mechanism of cell-to-cell communication. In the present study, we investigated the mechanisms underlying the interaction between MSCs and NPC cells. The data showed that MSCs secreted 40-100 nm heterogeneous small vesicles, which were defined as exosomes. Incubation of NPC cells with MSC-derived exosomes resulted in the uptake of exosomes by the cells, which promoted their proliferation, migration and tumorigenesis. After an extended treatment duration, the tumor cells showed morphological changes and significant changes in the expression of epithelial-mesenchymal transition (EMT) markers. Moreover, we found that FGF19 was highly expressed in MSC-exosomes and that exosomes stimulated NPC progression by activating the FGF19-FGFR4-dependent ERK signaling cascade and by modulating the EMT. All of these data indicated that exosomes participate in a novel mechanism by which MSCs influence NPC progression.