title: Plasma-activated medium induces A549 cell injury via a spiral apoptotic cascade involving the mitochondrial-nuclear network.
abstract: Plasma medicine is a rapidly expanding new field of interdisciplinary research that combines physics, chemistry, biology, and medicine. Nonthermal atmospheric pressure plasma can be applied to living cells and tissues and has emerged as a novel technology for cancer therapy. Plasma has recently been shown to affect cells not only directly, but also by indirect treatment with previously prepared plasma-activated medium (PAM). The objective of this study was to demonstrate the inhibitory effects of PAM on A549 cell survival and elucidate the signaling mechanisms responsible for cell death. PAM maintained its ability to suppress cell viability for at least 1 week when stored at -80°C. The severity of PAM-triggered cell injury depended on the kind of culture medium used to prepare the PAM, especially that with or without pyruvate. Hydrogen peroxide (H2O2) and/or its derived or cooperating reactive oxygen species reduced the mitochondrial membrane potential, downregulated the expression of the antiapoptotic protein Bcl2, activated poly(ADP-ribose) polymerase-1, and released apoptosis-inducing factor from mitochondria with endoplasmic reticulum stress. However, the activation of caspase 3/7 and attenuation of cell viability by the addition of caspase inhibitor were not observed. The accumulation of adenine 5'-diphosphoribose as a product of the above reactions activated transient receptor potential melastatin 2, which elevated intracellular Ca(2+) levels and subsequently led to cell death. These results demonstrated that H2O2 and/or other reactive species in PAM disturbed the mitochondrial-nuclear network in cancer cells through a caspase-independent apoptotic pathway. Moreover, damage to the plasma membrane by H2O2-cooperating charged species not only induced apoptosis, but also increased its permeability to extracellular reactive species. These phenomena were also detected in PAM-treated HepG2 and MCF-7 cells.
authors.affiliation: Laboratory of Clinical Pharmaceutics, Gifu Pharmaceutical University, 501-1196 Gifu, Japan. Electronic address: adachi@gifu-pu.ac.jp.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Adachi
authors.affiliation: Institute of Innovation for Future Society, Nagoya University, 464-8603 Nagoya, Japan.
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Tanaka
authors.affiliation: Laboratory of Clinical Pharmaceutics, Gifu Pharmaceutical University, 501-1196 Gifu, Japan.
authors.forename: Saho
authors.initials: S
authors.lastname: Nonomura
authors.affiliation: Laboratory of Clinical Pharmaceutics, Gifu Pharmaceutical University, 501-1196 Gifu, Japan.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Hara
authors.affiliation: Laboratory of Pharmaceutical Physical Chemistry, Gifu Pharmaceutical University, 501-1196 Gifu, Japan.
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Kondo
authors.affiliation: Institute of Innovation for Future Society, Nagoya University, 464-8603 Nagoya, Japan.
authors.forename: Masaru
authors.initials: M
authors.lastname: Hori
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis; D002460:Cell Line; D002467:Cell Nucleus / Q000502:physiology*; D006801:Humans; D008928:Mitochondria / Q000502:physiology*; D058626:Plasma Gases; D015398:Signal Transduction
chemical_list: D000975:Antioxidants; D058626:Plasma Gases
keywords: Caspase-independent apoptosis; Free radicals; Nonthermal atmospheric pressure plasma; PARP-1; Plasma-activated medium; Reactive oxygen and nitrogen species; TRPM2