Higher N2 gas-flow rate ratios in O2- and Ar-containing feed gas mixtures enhance the cytotoxic effects of radical-activated medium against murine melanoma B16F10 cells

Radical-activated medium (RAM), produced from cold atmospheric plasma irradiation of liquid cell culture medium, is of significant interest for its potential application in cancer treatment. In this study, murine melanoma B16F10 cells were used to examine the anticancer activity of RAMs generated from various plasma feed gas mixtures. RAMs generated from plasma feed gases containing O2 decreased cell viability, which was enhanced by N2. Mitochondrial membrane potentials decreased, whereas caspase-9 and caspase-3 activity increased, suggesting an induction of mitochondria-mediated apoptosis. Interestingly, caspase-3 activity was enhanced when N2 was present in the plasma feed gas. Moreover, only RAM generated from plasma feed gases containing N2 and O2 activated caspase-12 and c-Jun N-terminal kinase, which suggests an induction of endoplasmic reticulum-mediated apoptosis. Overall, the results suggest that N2 in the feed gas during RAM production enhances its anticancer activity by triggering both endoplasmic reticulum and mitochondria-mediated cell death.