On the Anti-Cancer Effect of Cold Atmospheric Plasma and the Possible Role of Catalase-Dependent Apoptotic Pathways

Differential eco-toxicological responses toward Eisenia fetida exposed to soil contaminated with naphthalene and typical metabolites

Naphthalene (NAP) was frequently detected in polycyclic aromatic hydrocarbons (PAHs)-contaminated soil, and its residues may pose an eco-toxicological threat to soil organisms. The toxic effects of NAP were closely tied to phenolic and quinone metabolites in biological metabolism. However, the present knowledge concerning the eco-toxicological impacts of NAP metabolites at the animal level is scanty. Here, we assessed the differences in the eco-toxicological responses of Eisenia fetida (E. fetida) in NAP, 1-naphthol (1-NAO) or 1,4-naphthoquinone (1,4-NQ) contaminated soils. NAP, 1-NAO, and 1,4-NQ exposure triggered the onset of oxidative stress as evidenced by the destruction of the antioxidant enzyme system. The lipid peroxidation and DNA oxidative damage levels induced by 1-NAO and 1,4-NQ were higher than those of NAP. The elevation of DNA damage varied considerably depending on differences in oxidative stress and the direct mode of action of NAP or its metabolites with DNA. All three toxicants induced different degrees of physiological damage to the body wall, but only 1, 4-NQ caused the shedding of intestinal epithelial cells. The integrated biomarker response for different exposure times illustrated that the comprehensive toxicity at the animal level was 1,4-NQ > 1-NAO > NAP, and the time-dependent trends of oxidative stress responses induced by the three toxicants were similar. At the initial stage, the antioxidant system of E. fetida responded positively to the provocation, but the ability of E. fetida to resist stimulation decreased with the prolongation of time resulting in provocation oxidative damage. This study would provide new insights into the toxicological effects and biohazard of PAHs on soil animals.

Human tissue-resident peritoneal macrophages reveal resistance towards oxidative cell stress induced by non-invasive physical plasma

In the context of multimodal treatments for abdominal cancer, including procedures such as cytoreductive surgery and intraperitoneal chemotherapy, recurrence rates remain high, and long-term survival benefits are uncertain due to post-operative complications. Notably, treatment-limiting side effects often arise from an uncontrolled activation of the immune system, particularly peritoneally localized macrophages, leading to massive cytokine secretion and phenotype changes. Exploring alternatives, an increasing number of studies investigated the potential of plasma-activated liquids (PAL) for adjuvant peritoneal cancer treatment, aiming to mitigate side effects, preserve healthy tissue, and reduce cytotoxicity towards non-cancer cells. To assess the non-toxicity of PAL, we isolated primary human macrophages from the peritoneum and subjected them to PAL exposure. Employing an extensive methodological spectrum, including flow cytometry, Raman microspectroscopy, and DigiWest protein analysis, we observed a pronounced resistance of macrophages towards PAL. This resistance was characterized by an upregulation of proliferation and anti-oxidative pathways, countering PAL-derived oxidative stress-induced cell death. The observed cellular effects of PAL treatment on human tissue-resident peritoneal macrophages unveil a potential avenue for PAL-derived immunomodulatory effects within the human peritoneal cavity. Our findings contribute to understanding the intricate interplay between PAL and macrophages, shedding light on the promising prospects for PAL in the adjuvant treatment of peritoneal cancer.

Phytochemical Estimation and Therapeutic Amelioration of Aesculus hippocastanum L. Seeds Ethanolic Extract in Gastric Ulcer in Rats Possibly by Inhibiting Prostaglandin Synthesis

OBJECTIVE

To quantify phytochemicals using liquid chromatography and mass spectroscopy (LCMS) analysis and explore the therapeutic effect of Aesculus hippocastanum L. (AH) seeds ethanolic extract against gastric ulcers in rats.

METHODS

Preliminary phytochemical testing and LCMS analysis were performed according to standard methods. For treatment, the animals were divided into 7 groups including normal control, ulcer control, self-healing, AH seeds low and high doses, ranitidine and per se groups. Rats were orally administered with 10 mg/kg of indomethacin, excluding the normal control group (which received 1% carboxy methyl cellulose) and the per se group (received 200 mg/kg AH seeds extract). The test group rats were then given 2 doses of AH seeds extract (100 and 200 mg/kg, respectively), while the standard group was given ranitidine (50 mg/kg). On the 11th day, rats in all groups were sacrificed, and their stomach was isolated to calculate the ulcer index, and other parameters such as blood prostaglandin (PGE2), tissue superoxide dismutase (SOD), catalase (CAT), malonyldialdehyde (MDA), and glutathione (GSH). All isolated stomach tissues were analyzed for histopathological findings.

RESULTS

The phytochemical examination shows that the AH seeds contain alkaloids, flavonoids, saponins, phenolic components, and glycosides. LCMS analysis confirms the presence of quercetin and rutin. The AH seeds extract showed significant improvement in gastric mucosa conditions after indomethacin-induced gastric lesions (P<0.01). Further marked improvement in blood PGE2 and antioxidant enzymes, SOD, CAT, MDA and GSH, were observed compared with self-healing and untreated ulcer-induced groups (P<0.01). Histopathology results confirmed that AH seeds extract improved the mucosal layer and gastric epithelial membrane in treated groups compared to untreated ulcer-induced groups.

CONCLUSIONS

LCMS report confirms the presence of quercetin and rutin in AH seeds ethanolic extract. The therapeutic effect of AH seeds extract against indomethacin-induced ulcer in rat model indicated the regenerated membrane integrity, with improved cellular functions and mucus thickness. Further, improved antioxidant enzyme level would help to reduce PGE2 biosynthesis.

Cold Atmospheric Plasma Activates Selective Photothermal Therapy of Cancer

Due to the body’s systemic distribution of photothermal agents (PTAs), and to the imprecise exposure of lasers, photothermal therapy (PTT) is challenging to use in treating tumor sites selectively. Striving for PTT with high selectivity and precise treatment is nevertheless important, in order to raise the survival rate of cancer patients and lower the likelihood of adverse effects on other body sections. Here, we studied cold atmospheric plasma (CAP) as a supplementary procedure to enhance selectivity of PTT for cancer, using the classical photothermic agent’s gold nanostars (AuNSs). In in vitro experiments, CAP decreases the effective power of PTT: the combination of PTT with CAP at lower power has similar cytotoxicity to that using higher power irradiation alone. In in vivo experiments, combination therapy can achieve rapid tumor suppression in the early stages of treatment and reduce side effects to surrounding normal tissues, compared to applying PTT alone. This research provides a strategy for the use of selective PTT for cancer, and promotes the clinical transformation of CAP.

Plasma-activated medium induces ferroptosis by depleting FSP1 in human lung cancer cells

Cold atmospheric plasma (CAP) that generates reactive oxygen species (ROS) has received considerable scientific attentions as a new type of anticancer. In particular, an indirect treatment method of inducing cancer cell death through plasma-activated medium (PAM), rather than direct plasma treatment has been well established. Although various cell death pathways such as apoptosis, necroptosis, and autophagy have been suggested to be involved in PAM-induced cell death, the involvement of ferroptosis, another type of cell death regulated by lipid ROS is largely unknown. This study reports, that PAM promotes cell death via ferroptosis in human lung cancer cells, and PAM increases intracellular and lipid ROS, thereby resulting in mitochondrial dysfunction. The treatment of cells with N-acetylcysteine, an ROS scavenging agent, or ferrostatin-1, a ferroptosis inhibitor, protects cells against PAM-induced cell death. Interestingly, ferroptosis suppressor protein 1 (FSP1) is downregulated upon PAM treatment. Furthermore, the treatment of cells with iFSP1, an inhibitor of FSP1, further enhances PAM-induced ferroptosis. Finally, this study demonstrates that PAM inhibits tumor growth in a xenograft model with an increase in 4-hydroxynoneal and PTGS2, a byproduct of lipid peroxidation, and a decrease in FSP1 expression. This study will provide new insights into the underlying mechanism and therapeutic strategies of PAM-mediated cancer treatment.

Impact of Reactive Oxygen and Nitrogen Species Produced by Plasma on Mdm2-p53 Complex

The study of protein–protein interactions is of great interest. Several early studies focused on the murine double minute 2 (Mdm2)–tumor suppressor protein p53 interactions. However, the effect of plasma treatment on Mdm2 and p53 is still absent from the literature. This study investigated the structural changes in Mdm2, p53, and the Mdm2–p53 complex before and after possible plasma oxidation through molecular dynamic (MD) simulations. MD calculation revealed that the oxidized Mdm2 bounded or unbounded showed high flexibility that might increase the availability of tumor suppressor protein p53 in plasma-treated cells. This study provides insight into Mdm2 and p53 for a better understanding of plasma oncology.

The Quest to Quantify Selective and Synergistic Effects of Plasma for Cancer Treatment: Insights from Mathematical Modeling

Cold atmospheric plasma (CAP) and plasma-treated liquids (PTLs) have recently become a promising option for cancer treatment, but the underlying mechanisms of the anti-cancer effect are still to a large extent unknown. Although hydrogen peroxide (H2O2) has been recognized as the major anti-cancer agent of PTL and may enable selectivity in a certain concentration regime, the co-existence of nitrite can create a synergistic effect. We develop a mathematical model to describe the key species and features of the cellular response toward PTL. From the numerical solutions, we define a number of dependent variables, which represent feasible measures to quantify cell susceptibility in terms of the H2O2 membrane diffusion rate constant and the intracellular catalase concentration. For each of these dependent variables, we investigate the regimes of selective versus non-selective, and of synergistic versus non-synergistic effect to evaluate their potential role as a measure of cell susceptibility. Our results suggest that the maximal intracellular H2O2 concentration, which in the selective regime is almost four times greater for the most susceptible cells compared to the most resistant cells, could be used to quantify the cell susceptibility toward exogenous H2O2. We believe our theoretical approach brings novelty to the field of plasma oncology, and more broadly, to the field of redox biology, by proposing new ways to quantify the selective and synergistic anti-cancer effect of PTL in terms of inherent cell features.

Intracellular Responses Triggered by Cold Atmospheric Plasma and Plasma-Activated Media in Cancer Cells

Cold atmospheric plasma (CAP), an ionized gas operating at room temperature, has been increasingly studied with respect to its potential use in medicine, where its beneficial effects on tumor reduction in oncology have been demonstrated. This review discusses the cellular changes appearing in cell membranes, cytoplasm, various organelles, and DNA content upon cells’ direct or indirect exposure to CAP or CAP-activated media/solutions (PAM), respectively. In addition, the CAP/PAM impact on the main cellular processes of proliferation, migration, protein degradation and various forms of cell death is addressed, especially in light of CAP use in the oncology field of plasma medicine.

Applications of Cold Atmospheric Pressure Plasma in Dentistry

Plasma is an electrically conducting medium that responds to electric and magnetic fields. It consists of large quantities of highly reactive species, such as ions, energetic electrons, exited atoms and molecules, ultraviolet photons, and metastable and active radicals. Non-thermal or cold plasmas are partially ionized gases whose electron temperatures usually exceed several tens of thousand degrees K, while the ions and neutrals have much lower temperatures. Due to the presence of reactive species at low temperature, the biological effects of non-thermal plasmas have been studied for application in the medical area with promising results. This review outlines the application of cold atmospheric pressure plasma (CAPP) in dentistry for the control of several pathogenic microorganisms, induction of anti-inflammatory, tissue repair effects and apoptosis of cancer cells, with low toxicity to healthy cells. Therefore, CAPP has potential to be applied in many areas of dentistry such as cariology, periodontology, endodontics and oral oncology.

Role of Short- and Long-Lived Reactive Species on the Selectivity and Anti-Cancer Action of Plasma Treatment In Vitro

Simple Summary

One fundamental feature that has emerged from in vitro application of cold plasmas in cancer treatment is the key role of the liquid phase covering the cells. In the present work, we investigated the effect of direct and indirect plasma treatments on two cancer and three normal cell lines to assess the benefits of one treatment over the other in terms of death of tumor versus healthy cells. Our results demonstrate that indirect plasma treatment is as efficient at killing tumor cells as an appropriate combination of H₂O₂, NO₂⁻ and acidic pH in ad hoc solutions, while sparing normal cells. However, direct plasma treatment is far more efficient at killing normal than tumor cells, and we provide evidence that short- and long-lived reactive species contribute synergistically to kill normal cells, while having an additive effect regarding tumor cell death. Collectively, our results call the use of plasma-activated liquid in cancer treatment into question.

Abstract

(1) Plasma-activated liquids (PAL) have been extensively studied for their anti-cancer properties. Two treatment modalities can be applied to the cells, direct and indirect plasma treatments, which differ by the environment to which the cells are exposed. For direct plasma treatment, the cells covered by a liquid are present during the plasma treatment time (phase I, plasma ON) and the incubation time (phase II, plasma OFF), while for indirect plasma treatment, phase I is cell-free and cells are only exposed to PAL during phase II. The scope of this work was to study these two treatment modalities to bring new insights into the potential use of PAL for cancer treatment. (2) We used two models of head and neck cancer cells, CAL27 and FaDu, and three models of normal cells (1Br3, NHK, and RPE-hTERT). PBS was used as the liquid of interest, and the concentration of plasma-induced H₂O₂, NO₂⁻ and NO₃⁻, as well as pH change, were measured. Cells were exposed to direct plasma treatment, indirect plasma treatment or reconstituted buffer (PBS adjusted with plasma-induced concentrations of H₂O₂, NO₂⁻, NO₃⁻ and pH). Metabolic cell activity, cell viability, lipid peroxidation, intracellular ROS production and caspase 3/7 induction were quantified. (3) If we showed that direct plasma treatment is slightly more efficient than indirect plasma treatment and reconstituted buffer at inducing lipid peroxidation, intracellular increase of ROS and cancer cell death in tumor cells, our data also revealed that reconstituted buffer is equivalent to indirect plasma treatment. In contrast, normal cells are quite insensitive to these two last treatment modalities. However, they are extremely sensitive to direct plasma treatment. Indeed, we found that phase I and phase II act in synergy to trigger cell death in normal cells and are additive concerning tumor cell death. Our data also highlight the presence in plasma-treated PBS of yet unidentified short-lived reactive species that contribute to cell death. (4) In this study, we provide strong evidence that, in vitro, the concentration of RONS (H₂O₂, NO₂⁻ and NO₃⁻) in combination with the acidic pH are the main drivers of plasma-induced PBS toxicity in tumor cells but not in normal cells, which makes ad hoc reconstituted solutions powerful anti-tumor treatments. In marked contrast, direct plasma treatment is deleterious for normal cells in vitro and should be avoided. Based on our results, we discuss the limitations to the use of PAL for cancer treatments.