Plasma-induced selectivity in bone cancer cells death

Plasma Treatment of Ovarian Cancer Cells Mitigates Their Immuno-Modulatory Products Active on THP-1 Monocytes

Cancers modulate their microenvironment to favor their growth. In particular, monocytes and macrophages are targeted by immuno-modulatory molecules installed by adjacent tumor cells such as ovarian carcinomas. Cold physical plasma has recently gained attention as innovative tumor therapy. We confirmed this for the OVCAR-3 and SKOV-3 ovarian cancer cell lines in a caspase 3/7 independent and dependent manner, respectively. To elaborate whether plasma exposure interferes with their immunomodulatory properties, supernatants of control and plasma-treated tumor cells were added to human THP-1 monocyte cultures. In the latter, modest effects on intracellular oxidation or short-term metabolic activity were observed. By contrast, supernatants of plasma-treated cancer cells abrogated significant changes in morphological and phenotypic features of THP-1 cells compared to those cultured with supernatants of non-treated tumor cell counterparts. This included cell motility and morphology, and modulated expression patterns of nine cell surface markers known to be involved in monocyte activation. This was particularly pronounced in SKOV-3 cells. Further analysis of tumor cell supernatants indicated roles of small particles and interleukin 8 and 18, with MCP1 presumably driving activation in monocytes. Altogether, our results suggest plasma treatment to alleviate immunomodulatory secretory products of ovarian cancer cells is important for driving a distinct myeloid cell phenotype.

The effect of reactive oxygen and nitrogen species on the structure of cytoglobin: A potential tumor suppressor

Many current anti-cancer therapies rely on increasing the intracellular reactive oxygen and nitrogen species (RONS) contents with the aim to induce irreparable damage, which subsequently results in tumor cell death. A novel tool in cancer therapy is the use of cold atmospheric plasma (CAP), which has been found to be very effective in the treatment of many different cancer cell types in vitro as well as in vivo, mainly through the vast generation of RONS. One of the key determinants of the cell's fate will be the interaction of RONS, generated by CAP, with important proteins, i.e. redox-regulatory proteins. One such protein is cytoglobin (CYGB), a recently discovered globin proposed to be involved in the protection of the cell against oxidative stress. In this study, the effect of plasma-produced RONS on CYGB was investigated through the treatment of CYGB with CAP for different treatment times. Spectroscopic analysis of CYGB showed that although chemical modifications occur, its secondary structure remains intact. Mass spectrometry experiments identified these modifications as oxidations of mainly sulfur-containing and aromatic amino acids. With longer treatment time, the treatment was also found to induce nitration of the heme. Furthermore, the two surface-exposed cysteine residues of CYGB were oxidized upon treatment, leading to the formation of intermolecular disulfide bridges, and potentially also intramolecular disulfide bridges. In addition, molecular dynamics and docking simulations confirmed, and further show, that the formation of an intramolecular disulfide bond, due to oxidative conditions, affects the CYGB 3D structure, thereby opening the access to the heme group, through gate functioning of His₁₁₇. Altogether, the results obtained in this study (1) show that plasma-produced RONS can extensively oxidize proteins and (2) that the oxidation status of two redox-active cysteines lead to different conformations of CYGB.

CAP modifies the structure of a model protein from thermophilic bacteria: mechanisms of CAP-mediated inactivation

Cold atmospheric plasma (CAP) has great potential for sterilization in the food industry, by deactivation of thermophilic bacteria, but the underlying mechanisms are largely unknown. Therefore, we investigate here whether CAP is able to denature/modify protein from thermophilic bacteria. We focus on MTH1880 (MTH) from Methanobacterium thermoautotrophicum as model protein, which we treated with dielectric barrier discharge (DBD) plasma operating in air for 10, 15 and 20 mins. We analysed the structural changes of MTH using circular dichroism, fluorescence and NMR spectroscopy, as well as the thermal and chemical denaturation, upon CAP treatment. Additionally, we performed molecular dynamics (MD) simulations to determine the stability, flexibility and solvent accessible surface area (SASA) of both the native and oxidised protein.

Anti-cancer capacity of plasma-treated PBS: effect of chemical composition on cancer cell cytotoxicity

We evaluate the anti-cancer capacity of plasma-treated PBS (pPBS), by measuring the concentrations of NO₂⁻ and H₂O₂ in pPBS, treated with a plasma jet, for different values of gas flow rate, gap and plasma treatment time, as well as the effect of pPBS on cancer cell cytotoxicity, for three different glioblastoma cancer cell lines, at exactly the same plasma treatment conditions. Our experiments reveal that pPBS is cytotoxic for all conditions investigated. A small variation in gap between plasma jet and liquid surface (10 mm vs 15 mm) significantly affects the chemical composition of pPBS and its anti-cancer capacity, attributed to the occurrence of discharges onto the liquid. By correlating the effect of gap, gas flow rate and plasma treatment time on the chemical composition and anti-cancer capacity of pPBS, we may conclude that H₂O₂ is a more important species for the anti-cancer capacity of pPBS than NO₂⁻. We also used a 0D model, developed for plasma-liquid interactions, to elucidate the most important mechanisms for the generation of H₂O₂ and NO₂⁻. Finally, we found that pPBS might be more suitable for practical applications in a clinical setting than (commonly used) plasma-activated media (PAM), because of its higher stability.

Cold Atmospheric Plasma in the Treatment of Osteosarcoma

Human osteosarcoma (OS) is the most common primary malignant bone tumor occurring most commonly in adolescents and young adults. Major improvements in disease-free survival have been achieved by implementing a combination therapy consisting of radical surgical resection of the tumor and systemic multi-agent chemotherapy. However, long-term survival remains poor, so novel targeted therapies to improve outcomes for patients with osteosarcoma remains an area of active research. This includes immunotherapy, photodynamic therapy, or treatment with nanoparticles. Cold atmospheric plasma (CAP), a highly reactive (partially) ionized physical state, has been shown to inherit a significant anticancer capacity, leading to a new field in medicine called “plasma oncology.” The current article summarizes the potential of CAP in the treatment of human OS and reviews the underlying molecular mode of action.

Cold atmospheric plasma in orthopaedic and urologic tumor therapy

Cold atmospheric plasma (CAP) is a highly reactive ionized physical state thereby provoking divers biological effects. In medical applications, CAP treatment promotes wound healing, provokes immunostimulation, and is antiseptically active. Moreover, CAP interacts with antiproliferative mechanisms suggesting CAP treatment as a promising anticancer strategy. Here we review the current state of science concerning the so far investigated CAP effects on different cancer entities in orthopaedic and urologic oncology.