Cold Atmospheric Plasma Changes the Amino Acid Composition of Solutions and Influences the Anti-Tumor Effect on Melanoma Cells.

Stephanie Arndt,Anja-Katrin Bosserhoff,Petra Unger,Julia L Zimmermann,Claudia Samol,Sigrid Karrer,Michael Gruber,Wolfram Gronwald,Katja Dettmer,Fadi Fadil,Marko Boskovic

doi:10.3390/ijms22157886

Abstract

Cold Atmospheric Plasma (CAP) is an ionized gas near room temperature. Its anti-tumor effect can be transmitted either by direct treatment or mediated by a plasma-treated solution (PTS), such as treated standard cell culture medium, which contains different amino acids, inorganic salts, vitamins and other substances. Despite extensive research, the active components in PTS and its molecular or cellular mechanisms are not yet fully understood. The purpose of this study was the measurement of the reactive species in PTS and their effect on tumor cells using different plasma modes and treatment durations. The PTS analysis yielded mode- and dose-dependent differences in the production of reactive oxygen and nitrogen species (RONS), and in the decomposition and modification of the amino acids Tyrosine (Tyr) and Tryptophan (Trp). The Trp metabolites Formylkynurenine (FKyn) and Kynurenine (Kyn) were produced in PTS with the 4 kHz (oxygen) mode, inducing apoptosis in Mel Im melanoma cells. Nitrated derivatives of Trp and Tyr were formed in the 8 kHz (nitrogen) mode, elevating the p16 mRNA expression and senescence-associated ß-Galactosidase staining. In conclusion, the plasma mode has a strong impact on the composition of the active components in PTS and affects its anti-tumor mechanism. These findings are of decisive importance for the development of plasma devices and the effectiveness of tumor treatment.

Highlights

Cold Atmospheric Plasma (CAP) is of interest in a variety of medical applications, such as sterilization [1], wound healing [2,3], virus inactivation [4] and cancer treatment [5]
The aim of the study was to examine the molecular and cellular reactions of tumor cells induced by plasma-treated solutions (PTS) that had been generated by means of the plasma care® device using frequencies of 4 kHz and 8 kHz
In order to examine which reactive oxygen and nitrogen species (RONS) are produced in plasma-treated medium (PTS), long-lived reactive oxygen species (ROS) were determined based on the scaling of Dihydrorhodamine 123 (DHR 123) fluorescence, hydrogen peroxide (H2O2) and reactive nitrogen species (RNS) by measuring nitrite (NO2−) and nitrate (NO3−)

Summary

Introduction

Cold Atmospheric Plasma (CAP) is of interest in a variety of medical applications, such as sterilization [1], wound healing [2,3], virus inactivation [4] and cancer treatment [5]. Various in vitro and animal studies have shown efficacious anti-proliferative and pro-apoptotic effects on tumor cells after CAP treatment [13,14,15,16,17,18]. Indirect plasma treatment may have the advantage of targeting cancer cells inside the body because of its injection into the tumor tissue. H2O2, NO2− and NO3− have been described as the three main active components responsible for the anti-tumor effects of PTS [28], as other short-lived species are quenched very rapidly [29].

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