Exosome-mediated Induction of Apoptosis in Cisplatin-treated Gastric Cancer Cells as a Strategy to Mitigate Side Effects

Background: Gastric cancer is the third most lethal malignancy worldwide. While cisplatin has shown remarkable efficacy at a low cost, it is also associated with severe side effects. Exosomes play a key role in mediating the bystander effect of radiation and have the capacity to deliver apoptosis signals for targeted destruction of tumor cell. However, there remains a paucity of research on exosome-mediated bystander effects in the context of chemotherapeutic drugs. Objective: This study aims to investigate the ability of cisplatin-induced exosomes to deliver apoptosis signals to gastric cancer cells, with the aim of mitigating the adverse effects associated with chemotherapy. Methods: Differential ultracentrifugation was used to isolate apoptotic exosomes secreted by cisplatin-induced gastric cancer MKN-28 cells. Characterization and identification of these exosomes were performed by transmission electron microscopy, particle size analyzer, flow cytometry, and Western blotting. The transduction efficiency of the exosomes was confirmed through immunefluorescence. The effects of apoptotic exosomes on the proliferation, apoptosis, migration, cycle, senescence, and tumor formation of MKN-28 cells in vitro and in vivo were investigated by live cell workstation, flow cytometry, HE staining, and tumorigenicity assays. Results: Cisplatin-induced apoptotic exosomes, termed DDP-EXO, exhibited a significantly enhanced inhibitory effect on the proliferation of MKN-28 cells compared to gastric epithelial GES-1 cells. Moreover, DDP-EXO was able to deliver apoptotic signals to MKN-28 cells, leading to an increase in the apoptotic population in recipient cells, possibly through the involvement of Caspase-9. Furthermore, DDP-EXO showed limited impacts on cell migration, cell cycle, or cell senescence. In vivo, DDP-EXO effectively suppressed tumorigenesis in a subcutaneous tumor model without causing detectable pathological changes in main organs and blood samples, suggesting a favorable safety profile. Conclusion: In summary, this study provides new perspectives on the potential application of exosomes as an innovative therapeutic approach for gastric cancer.