Differences in intracellular mobile zinc levels affect susceptibility to plasma-activated medium-induced cytotoxicity.
There is growing evidence that plasma-activated medium (PAM), which is prepared by non-thermal plasma (NTP) irradiation of cell-free medium, is a beneficial tool for cancer therapy. PAM has been reported to preferentially kill cancer cells; however, its mechanism is not fully understood. Since PAM contains reactive oxygen species (ROS) and reactive nitrogen species, the anti-cancer effects of PAM are thought to be attributed to oxidative stress induced by these reactive molecules. Oxidative stress has been shown to release zinc (Zn2+) from intracellular Zn2+stores and provoke Zn2+-dependent cell death. We have previously demonstrated that intracellular free Zn2+plays a critical role in PAM-induced cell death in human neuroblastoma SH-SY5Y cells. In this study, we found that normal human fibroblasts were less susceptible to PAM cytotoxicity compared with SH-SY5Y cells. PAM decreased intracellular NAD+levels in both cells, whereas the depletion of ATP and mitochondrial ROS generation was hardly observed in fibroblasts. Intracellular mobile Zn2+contents of fibroblasts were lower than those of SH-SY5Y cells. PAM suppressed the activity of aconitase, which is a tricarboxylic acid cycle enzyme, only in SH-SY5Y cells, and N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), a Zn2+chelator, counteracted the suppression. The combination treatment with PAM and Zn2+augmented PAM-induced ATP depletion, mitochondrial ROS generation, and cytotoxicity in fibroblasts. These findings suggest the possibility that cells with high intracellular mobile Zn2+are susceptible to PAM cytotoxicity. Therefore, we concluded that the differences in mobile Zn2+levels affect PAM-induced cellular responses.
a Laboratory of Clinical Pharmaceutics, Gifu Pharmaceutical University , Gifu , Japan.
Hirokazu
H
Hara
a Laboratory of Clinical Pharmaceutics, Gifu Pharmaceutical University , Gifu , Japan.
Sayako
S
Sueyoshi
a Laboratory of Clinical Pharmaceutics, Gifu Pharmaceutical University , Gifu , Japan.
Miko
M
Taniguchi
a Laboratory of Clinical Pharmaceutics, Gifu Pharmaceutical University , Gifu , Japan.
Tetsuro
T
Kamiya
a Laboratory of Clinical Pharmaceutics, Gifu Pharmaceutical University , Gifu , Japan.
Tetsuo
T
Adachi
D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects / Q000528:radiation effects; D002614:Chelating Agents / Q000008:administration & dosage; D005347:Fibroblasts / Q000187:drug effects / Q000528:radiation effects; D006801:Humans; D008928:Mitochondria / Q000528:radiation effects; D009447:Neuroblastoma / Q000188:drug therapy* / Q000473:pathology / Q000532:radiotherapy*; D018384:Oxidative Stress / Q000187:drug effects / Q000528:radiation effects*; D058626:Plasma Gases; D026361:Reactive Nitrogen Species / Q000378:metabolism / Q000528:radiation effects; D017382:Reactive Oxygen Species / Q000378:metabolism / Q000528:radiation effects; D015032:Zinc / Q000378:metabolism*
D002614:Chelating Agents; D058626:Plasma Gases; D026361:Reactive Nitrogen Species; D017382:Reactive Oxygen Species; D015032:Zinc
Plasma-activated medium; ROS; mitochondria; non-thermal plasma; zinc