Effect of hyperthermic CO₂-treated dendritic cell-derived exosomes on the human gastric cancer AGS cell line

The aim of the present study was to determine the antitumor effects of hyperthermic CO₂ (HT-CO₂)-treated dendritic cell (DC)-derived exosomes (Dex) on human gastric cancer AGS cells. Mouse-derived DCs were incubated in HT-CO₂ at 43°C for 4 h. The exosomes in the cell culture supernatant were then isolated. Cell proliferation was analyzed using the cell counting kit-8 (CCK-8) assay. Cell apoptosis was observed using flow cytometry, Hoechst 33258 staining and the analysis of caspase-3 activity. In addition, the proliferation of tumor cells was evaluated in xenotransplant nude mice. HT-CO₂ markedly inhibited cell proliferation, as assessed by the CCK-8 assay, and also induced apoptosis in a time-dependent manner, as demonstrated by Annexin V/propidium iodide flow cytometry, caspase-3 activity and morphological analysis using Hoechst fluorescent dye. It was also revealed that HT-CO₂-treated Dex decreased the expression of heat shock protein 70 and inhibited tumor growth in nude mice. In conclusion, HT-CO₂ exerted an efficacious immune-enhancing effect on DCs. These findings may provide a novel strategy for the elimination of free cancer cells during laparoscopic resection. However, the potential cellular mechanisms underlying this process require further investigation.