Exosome/staphylococcal enterotoxin B, an anti tumor compound against pancreatic cancer.

Purpose: Exosomes (EXOs) are acellular vehicles used for cancer immunotherapy due to their immune-inducing properties. We synthesized a novel structure based on EXOs and staphylococcal enterotoxin B (SEB) and surveyed its cytostatic effect on a pancreatic cell line. Methods: EXOs were purified from tumor cells and SEB was anchored on it by protein transfer method. To determine the cytotoxic and apoptosis-inducing effect of this structure, treated cells with different concentrations of EXO/SEB were examined by MTT assay and Hoechst staining method. In addition, the expression rate of bcl-2, bax, bak, fas, bcl-xl and the activity of caspase-3 and caspase-9 were assessed. Results: We observed that 0.5 and 2.5 μg/100μl of EXO/ SEB significantly (p<0.001) stimulated apoptosis after 24 hrs. The concentrations of 0.5 and 2.5μg/100μl of EXO/SEB raised the expression rate of bax, bak, fas (p<0.001) but had no impact on bcl-2 and bcl-xl after 48 hrs. Furthermore, it was shown that 0.5, 2.5 and 5 μg/100μl of EXO/SEB only increased the activity of caspase-3 after 48 hrs (p<0.001). Conclusion: Our designed structure, the EXO/SEB, is a novel model being able to induce apoptosis.