Nonthermal plasma induces head and neck cancer cell death: the potential involvement of mitogen-activated protein kinase-dependent mitochondrial reactive oxygen species

Abstract

Nonthermal plasma (NTP) is generated by ionization of neutral gas molecules, which results in a mixture of energy particles including electrons and ions. Recent progress in the understanding of NTP has led to its application in the treatment of various diseases, including cancer. However, the molecular mechanisms of NTP-induced cell death are unclear. The purpose of this study was to evaluate the molecular mechanism of NTP in the induction of apoptosis of head and neck cancer (HNC) cells. The effects of NTP on apoptosis were investigated using MTT, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling, Annexin V assays, and western blot analysis. The cells were examined for production of reactive oxygen species (ROS) using DCFCA or MitoSOX staining, intracellular signaling, and an animal model. NTP reduced HNC cell viability in a dose-dependent manner and induced apoptosis. NTP resulted in alteration of mitochondrial membrane potential and accumulation of intracellular ROS generated from the mitochondria in HNC cells. Blockade of ROS production by N-acetyl-L-cysteine inhibited NTP-induced apoptosis. NTP led to the phosphorylation of c-JUN N-terminal kinase (JNK) and p38, but not extracellular-regulated kinase. Treatment with JNK and p38 inhibitors alleviated NTP-induced apoptosis via ROS generation. Taken together, these results show that NTP induced apoptosis of HNC cells by a mechanism involving MAPK-dependent mitochondrial ROS. NTP inhibited the growth of pre-established FaDu tumors in a nude mouse xenograft model and resulted in accumulation of intracellular ROS. In conclusion, NTP induced apoptosis in HNC cells through a novel mechanism involving MAPK-mediated mitochondrial ROS. These findings show the therapeutic potential of NTP in HNC.

Cell migration and adhesion of a human melanoma cell line is decreased by cold plasma treatment

“…We obtained similar results investigating phosphatidylserine exposure using Annexin V which further supports the notion that induction of apoptosis was negligible (data not shown). This is in disagreement with findings of other groups which, however, used different plasma sources and/or cell lines in their experimentations [19][20][21]. These studies have shown plasma-reduced cancer cell viability and induced apoptosis in a dose-dependent manner.…”

“…apoptosis) in several tumor cells [17]. Applying plasmagenerated ROS, an induction of apoptosis was shown in melanocytic tumors in mice [18], in p53-mutated cancer cells [19], and in head and neck carcinoma in vivo [20] as well as in several other models [21]. Most studies have focused on tumor cell death after cold plasma treatment.…”

Upconversion nanoparticle-mediated photodynamic therapy induces THP-1 macrophage apoptosis via ROS bursts and activation of the mitochondrial caspase pathway

“…However, the overproduction of ROS may damage lipids, proteins, and DNA. 45 This study demonstrated that intracellular ROS production was increased significantly and peaked at 3 hours following PDT treatment ( Figure 4B). There are two explanations for this increase in ROS: 1) the photosensitizer may transfer its energy to form highly reactive 1 O 2 when oxygen is present in the environment as previous studies have reported that 1 O 2 may be one of the mediators of the imbalance in intracellular ROS; 29 and 2) the activated photosensitizer may react directly with organic substrates or via electron or hydrogen transfer to yield free radicals.…”

Biphasic effects of l-ascorbate on the tumoricidal activity of non-thermal plasma against malignant mesothelioma cells

“…Furthermore, NTP has been proposed as a novel anticancer therapeutic strategy [17]. This is based on the fact that NTP induces its cytotoxic effects through generating oxidative stress [18,19] specifically on cancer cells, including ovarian carcinoma [20,21], head and neck carcinoma [22], colorectal cancer and glioblastoma [23]. Interestingly, a recent study examining pancreatic carcinoma cells (MIAPaCa2) revealed the merit of the combined use of NTP and the anti-metabolite, gemcitabine [24].…”