Cytotoxicity of Nonthermal Plasma Treatments on Three Cancer Cell Lines Induces Changes in Cell Morphology and in HSP70 Gene Expression

Nonthermal plasma processes recently emerged as promising therapeutic tools for the treatment of cancer. Most anticancer effects of plasma have been related to the induction of oxidative stress due to the release of reactive oxygen and nitrogen species (RONS), among other plasma components, during discharge. The exact mechanism of action in the eradication of cancer, though, is still far from being fully understood. In this research, three cancer-derived cell lines were exposed to pulsed dielectric barrier discharge (DBD) to investigate the effect of direct plasma exposure on cancer cells. Among many cellular functions, cell adhesion and morphology were found to be visibly influenced. Morphological assays showed the inhibition of intercellular adhesion, losses in cell clustering, and changes in the external shape and actin cytoskeleton. These effects were related to the decrease in cell viability and plasma operational conditions. The increased expression of the heat shock protein HSP70 in plasma-exposed Saos2 cells confirmed that changes in morphology and viability in cancer cells are representative of internal changes in the oxidative state of cells that are caused by plasma-induced oxidative stress.