Toxicity and Immunogenicity in Murine Melanoma following Exposure to Physical Plasma‐Derived Oxidants

Abstract

Metastatic melanoma is an aggressive and deadly disease. Therapeutic advance has been achieved by antitumor chemo- and radiotherapy. These modalities involve the generation of reactive oxygen and nitrogen species, affecting cellular viability, migration, and immunogenicity. Such species are also created by cold physical plasma, an ionized gas capable of redox modulating cells and tissues without thermal damage. Cold plasma has been suggested for anticancer therapy. Here, melanoma cell toxicity, motility, and immunogenicity of murine metastatic melanoma cells were investigated following plasma exposure in vitro. Cells were oxidized by plasma, leading to decreased metabolic activity and cell death. Moreover, plasma decelerated melanoma cell growth, viability, and cell cycling. This was accompanied by increased cellular stiffness and upregulation of zonula occludens 1 protein in the cell membrane. Importantly, expression levels of immunogenic cell surface molecules such as major histocompatibility complex I, calreticulin, and melanocortin receptor 1 were significantly increased in response to plasma. Finally, plasma treatment significantly decreased the release of vascular endothelial growth factor, a molecule with importance in angiogenesis. Altogether, these results suggest beneficial toxicity of cold plasma in murine melanomas with a concomitant immunogenicity of potential interest in oncology.

Activation of Murine Immune Cells upon Co-culture with Plasma-treated B16F10 Melanoma Cells

“…Presence of FCS during plasma treatment was of minor importance corroborating previous results that excess protein has negligible effects on plasma-derived long-lived oxidants [36]. Plasma-induced tumor cell death supposedly was of an immunogenic nature, as release of ATP and CXCL1 suggests [48], which is in line with earlier reports [34,35,49,50].…”

“…High species concentrations can be used to exploit apoptotic redox signaling pathways in tumor cells [29], and first cancer patients have benefited from plasma therapy [30]. Plasma treatment can act in concert with other drugs [31][32][33], and plasma-generated reactive species induce pro-immunogenic molecules on tumor cells, such as ecto-calreticulin (CRT) [34][35][36]. Although the release of this and other DAMP signals after plasma treatment in melanoma cells has been shown, evidence of immune cell activation in response to plasma-treated melanoma is scarce.…”

Molecular Mechanisms of the Efficacy of Cold Atmospheric Pressure Plasma (CAP) in Cancer Treatment

“…Within the tumor microenvironment, they recognize tumor antigens and lyse the target cells, helping the body to fight cancer using its endogenous weapons provided by the immune system. Using direct plasma treatment or plasma-conditioned liquids, ICD has been observed in vitro in a number of tumor cell types including, for instance, pancreatic cancer, colorectal cancer, lung cancer, and malignant melanoma [99,[131][132][133][134][135][136][137][138][139][140]. Due to the extensive poly-pragmasia of plasma sources used in the field of plasma medicine, the central mechanisms underlying plasma-induced ICD have not been commonly unraveled.…”

Modifying the Tumour Microenvironment: Challenges and Future Perspectives for Anticancer Plasma Treatments

“…Plasma treatments have shown to increase T cell infiltration in murine pancreatic tumours, which could be related to the activation of immunogenic cell death of cancer cells, expressing calreticulin and releasing damage-associated molecular patterns [124]. Additionally, it has been proposed that plasma-derived ROS could upregulate the expression of major histocompatibility complex-I, favouring antigen presentation by cancer cells which could result in an increased number of intratumoural CD8+ T cells [125,126]. In the same way, B cells may play an important role in modulating the tumour response, as they can secrete IL-10 and TGF-β to favour tumour cell proliferation.…”