Pleiotropic Devitalization of Renal Cancer Cells by Non-Invasive Physical Plasma: Characterization of Molecular and Cellular Efficacy

Short-term Effects of Non-invasive Physical Plasma Treatment on Genomic Stability

BACKGROUND/AIM

The application of non-invasive physical plasma (NIPP) generates reactive oxygen species. These can lead to chemical oxidation of cellular molecules including DNA. On the other hand, NIPP can induce therapeutically intended apoptosis, which also leads to DNA fragmentation in the late phase. Therefore, to assess unwanted genotoxic effects, the formation of DNA damage was investigated in this study in discrimination from apoptotic processes.

MATERIALS AND METHODS

Mutation events after NIPP application were analyzed in CCL-93 fibroblast cells using the hypoxanthine phosphoribosyl transferase assay. Additionally, DNA single-strand breaks (SSB) and double-strand breaks (DSB) were quantified by performing the alkaline comet assay, and terminal deoxynucleotidyl transferase dUTP nick-end labeling assay. DSBs were quantified by phospho-histone 2AX-p53-binding protein 1 co-localization DSB focus assay. The data were compared with cell death quantification by the caspase-3/7 apoptosis assay.

RESULTS

Treatment with NIPP led to exceedingly rapid damage to genomic DNA and the appearance of DNA SSBs and DSBs in the initial 4 h. However, damage decreased again within the first 4-8 h, then the late phase began, characterized by DNA DSB and increasing caspase-3/7 activation.

CONCLUSION

Although NIPP treatment leads to extremely rapid damage to genomic DNA, this damage is reversed very quickly by efficient DNA-repair processes. As a consequence, only those cells whose genome damage can be repaired actually survive and proliferate. Persistent genotoxic effects were not observed in the cell system used.

Enhancing the Impact of Chemotherapy on Ewing Sarcoma Cells through Combination with Cold Physical Plasma

Although Ewing's sarcoma (ES) is a rare, but very aggressive tumor disease affecting the musculoskeletal system, especially in children, it is very aggressive and difficult to treat. Although medical advances and the establishment of chemotherapy represent a turning point in the treatment of ES, resistance to chemotherapy, and its side effects, continue to be problems. New treatment methods such as the application of cold physical plasma (CPP) are considered potential supporting tools since CPP is an exogenous source of reactive oxygen and nitrogen species, which have similar mechanisms of action in the tumor cells as chemotherapy. This study aims to investigate the synergistic effects of CPP and commonly used cytostatic chemotherapeutics on ES cells. The chemotherapy drugs doxorubicin and vincristine, the most commonly used in the treatment of ES, were applied to two different ES cell lines (RD-ES and A673) and their IC₂₀ and IC₅₀ were determined. In addition, individual chemotherapeutics in combination with CPP were applied to the ES cells and the effects on cell growth, cell viability, and apoptosis processes were examined. A single CPP treatment resulted in the dose-dependent growth inhibition of ES cells. The combination of different cytostatics and CPP led to significant growth inhibition, a reduction in cell viability, and higher rates of apoptosis compared to cells not additionally exposed to CPP. The combination of CPP treatment and the application of cytostatic drugs to ES cells showed promising results, significantly enhancing the cytotoxic effects of chemotherapeutic agents. These preclinical in vitro data indicate that the use of CPP can enhance the efficacy of common cytostatic chemotherapeutics, and thus support the translation of CPP as an anti-tumor therapy in clinical routine.