Synergistic Effects of Melittin and Plasma Treatment: A Promising Approach for Cancer Therapy

Epilipidomics reveals lipid fatty acid and headgroup modification in gas plasma-oxidized biomembranes

Lipids, possessing unsaturated fatty acid chains and polar regions with nucleophilic heteroatoms, represent suitable oxidation targets for autologous and heterologous reactive species. Lipid peroxidation products (LPPs) are highly heterogeneous, including hydroperoxides, alkenals, chlorination, or glycation. Accordingly, delineation of lipid targets, species type, resulting products, and oxidation level remains challenging. To this end, liposomal biomimetic models incorporating a phosphatidylcholine, -ethanolamine, and a sphingomyelin were used to deconvolute effects on a single lipid scale to predict potential modification product outcomes. To introduce oxidative modifications, gas plasma technology, a powerful pro-oxidant tool to promote LPP formation by forming highly abundant reactive species in the gas and liquid phases, was employed to liposomes. The plasma parameters (gas type/combination) were modified to modulate the resulting species-profile and LPP formation by enriching specific reactive species types over others. HR-LC-MS (Münzel and et al., 2017) [2] was employed for LPP identification. Moreover, the heavy oxygen isotope 18O was used to trace O2-incorporation into LPPs, providing first information on the plasma-mediated lipid peroxidation mechanism. We found that combination of lipid class and gas composition predetermined the type of attack: admixture of O2 to the plasma and the presence of nitrogen atoms with free electrons in the molecule lead to chlorination of the amide bond and headgroup. Here, atomic oxygen driven formation of hypochlorite is the major reactive species. In contrast, POPC yields mainly to LPPs with oxidation of the oleic acid tail, especially truncations, epoxidation, and hydroperoxide formation. Here, singlet oxygen is assumingly the major driver. 18O labelling revealed that gas phase derived reactive species are dominantly incorporated into the LPPs, supporting previous findings on gas-liquid interface chemistry. In summary, we here provided the first insights into gas plasma-mediated lipid peroxidation, which, employed in more complex cell and tissue models, may support identifying mechanisms of actions in plasma medicine.

Melittin and phospholipase A2: Promising anti-cancer candidates from bee venom

As the research on cancer-related treatment deepens, integrating traditional therapies with emerging interventions reveals new therapeutic possibilities. Melittin and phospholipase A2, the primary anti-cancer components of bee venom, are currently gaining increasing attention. This article reviews the various formulations of melittin in cancer therapy and its potential applications in clinical treatments. The reviewed formulations include melittin analogs, hydrogels, adenoviruses, fusion toxins, fusion peptides/proteins, conjugates, liposomes, and nanoparticles. The article also explored the collaborative therapeutic effects of melittin with natural products, synthetic drugs, radiotherapy, and gene expression regulatory strategies. Phospholipase A2 plays a key role in bee venom anti-cancer strategy due to its unique biological activity. Using an extensive literature review and the latest scientific results, this paper explores the current state and challenges of this field, with the aim to provide new perspectives that guide future research and potential clinical applications. This will further promote the application of bee venom in cancer therapy.

Determining the Effect of Non-Thermal Plasma on the Transmembrane Kinetics of Melittin through Molecular Explorations

Non-thermal plasma (NTP) synergistic anticancer strategies are a current hotspot of interest at the intersection of plasma biomedicine. Melittin (MEL) has been shown to inhibit cancer in many malignant tumors; however, its clinical application is controversial. Therefore, the transmembrane process and mechanism of MEL activity in different cell systems were studied and the combination of MEL and NTP was proposed in this paper. The results showed that the electrostatic attraction between MEL and the lipid bilayer contributes to the stable orientation of MEL on the membrane surface. In addition, sialic acid overexpression affects the degree to which MEL binds the membrane system and the stability of the membrane structure. The use of NTP to reduce the dosage of MEL and its related nonspecific cytolysis activity has certain clinical application value. The results of this study provide theoretical support for improving the clinical applicability of MEL and contribute to the further development of plasma biomedicine.

Cold atmospheric plasma activated media selectively affects human head and neck cancer cell lines

OBJECTIVE

Cold atmospheric plasma (CAP) is a novel approach for cancer treatment. It can be used to treat liquids-plasma-activated media (PAM)-which are then transferred to the target as an exogenous source of reactive oxygen and nitrogen species (RONS). The present study aimed at chemically characterizing different PAM and assessing their in vitro selectivity against head and neck cancer cells (HNC).

METHODS

PAM were obtained by exposing 2 and 5 mL of cell culture medium to CAP for 5, 10 and 20 min at a 6 mm working distance. Anions kinetics was evaluated by ion chromatography. Cell proliferation inhibition, apoptosis occurrence, and cell cycle modifications were assessed by MTS and flow cytometry, on human epidermal keratinocyte (HaCaT) and HNC cell lines HSC3, HSC4 and A253.

RESULTS

The 2 mL conditions showed a significant reduction in cell proliferation whereas for the 5 mL the effect was milder, but the time-dependence was more evident. HaCaT were unaffected by the 5 mL PAM, indicating a selectivity for cancer cells.

CONCLUSIONS

The media chemical composition modified by CAP exposure influenced cell proliferation by modulating cell cycle and inducing apoptosis in cancer cells, without affecting normal cells.

Antimicrobial efficacy of direct air gas soft jet plasma for the in vitro reduction of oral bacterial biofilms

The aim of this study was to evaluate the antimicrobial efficacy of an air gas soft jet CAP for its potential use in removing oral biofilms, given that plasma-based technologies have emerged as promising methods in periodontology. Two types of biofilms were developed, one by Streptococcus mutans UA 159 bacterial strain and the other by a complex mixture of saliva microorganisms isolated from a patient with periodontitis. This latter biofilm was characterized via Next Generation Sequencing to determine the main bacterial phyla. The CAP source was applied at a distance of 6 mm for different time points. A statistically significant reduction of both CFU count and XTT was already detected after 60 s of CAP treatment. CLSM analysis supported CAP effectiveness in killing the microorganisms inside the biofilm and in reducing the thickness of the biofilm matrix. Cytotoxicity tests demonstrated the possible use of CAP without important side effects towards human gingival fibroblasts cell line. The current study showed that CAP treatment was able to significantly reduce preformed biofilms developed by both S. mutans and microorganisms isolated by a saliva sample. Further studies should be conducted on biofilms developed by additional saliva donors to support the potential of this innovative strategy to counteract oral pathogens responsible for periodontal diseases.

Hybrid bio-nanoporous peptide loaded-polymer platforms with anticancer and antibacterial activities

In this study, hybrid bio-nanoporous peptides loaded onto poly(N-isopropylacrylamide-co-butylacrylate) (pNIPAM-co-BA) coatings were designed and obtained via matrix-assisted pulsed laser evaporation (MAPLE) technique. The incorporation of cationic peptides magainin (MG) and melittin (Mel) and their combination was tailored to target synergistic anticancer and antibacterial activities with low toxicity on normal mammalian cells. Atomic force microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy as well as contact angle and surface energy measurements revealed the successful and functional incorporation of both the peptides within porous polymeric nanolayers as well as surface modifications (i.e. variation in the pore size diameter, surface roughness, and wettability) after Mel, MG or Mel-MG incorporation compared to pNIPAM-co-BA. In vitro testing revealed the impairment of biofilm formation on all the hybrid coatings while testing with S. aureus, E. coli and P. aeruginosa. Moreover, MG was shown to modulate the effect of Mel in the combined Mel-MG extract formulation released via pNIPAM-platforms, thus significantly reducing cancer cell proliferation through apoptosis/necrosis as revealed by flow cytometry analysis performed in vitro on HEK293T, A375, B16F1 and B16F10 cells. To the best of our knowledge, Mel-MG combination entrapped in the pNIPAM-co-BA copolymer has not yet been reported as a new promising candidate with anticancer and antibacterial properties for improved utility in the biomedical field. Mel-MG incorporation compared to pNIPAM-co-BA in in vitro testing revealed the impairment of biofilm formation in all the hybrid formulations.

A Ratiometric Gene-Switch System for miRNA Sensing and Gene Regulation

microRNAs (miRNAs) are a class of non-coding, small RNAs that play an important role in diverse biological processes and diseases. By regulating the expression of eukaryotic genes post-transcriptionally in a sequence-specific manner, miRNAs are widely used to design synthetic RNA switches. However, most of the RNA switches are often dependent on the corresponding ligand molecules, whose specificity and concentration would affect the efficiency of synthetic RNA circuits. Here, a fused transcriptional repressor Gal4BD-Rluc based gene-switch system Gal-miR for miRNA visualization and gene regulation is described. By placing a luciferase downstream gene under the control of endogenous miRNA machinery, the Gal-miR system makes the conversion of miRNA-mediated gene silencing into a ratiometric bioluminescent signal, which quantitatively reflected miRNA-206 activity during myogenic differentiation. Moreover, it demonstrates that this gene-switch system can effectively inhibit breast cancer cell viability, migration and invasion under the control of specific miRNAs by replacing the downstream gene with melittin functional gene. The study proposes a powerful modular genetic design for achieving precise control of transgene expression in a miRNA responsive way, as well as visualizing the dynamics of miRNA activity.

Melittin: a possible regulator of cancer proliferation in preclinical cell culture and animal models

BACKGROUND

Melittin is a water-soluble cationic peptide derived from bee venom that has been thoroughly studied for the cure of different cancers. However, the unwanted interactions of melittin produce hemolytic and cytotoxic effects that hinder their therapeutic applications. To overcome the shortcomings, numerous research groups have adopted different approaches, including conjugation with tumor-targeting proteins, gene therapy, and encapsulation in nanoparticles, to reduce the non-specific cytotoxic effects and potentiate their anti-cancerous activity.

PURPOSE

This article aims to provide mechanistic insights into the chemopreventive activity of melittin and its nanoversion in combination with standard anti-cancer drugs for the treatment of cancer.

METHODS

We looked over the pertinent research on melittin's chemopreventive properties in online databases such as PubMed and Scopus.

CONCLUSION

In the present article, the anti-cancerous effects of melittin on different cancers have been discussed very nicely, as have their possible mechanisms of action to act against different tumors. Besides, it interacts with different signal molecules that regulate the diverse pathways of cancerous cells, such as cell cycle arrest, apoptosis, metastasis, angiogenesis, and inflammation. We also discussed the recent progress in the synergistic combination of melittin with standard anti-cancer drugs and a nano-formulated version of melittin for targeted delivery to improve its anticancer potential.

Effects of Nitro-Oxidative Stress on Biomolecules: Part 1-Non-Reactive Molecular Dynamics Simulations

Plasma medicine, or the biomedical application of cold atmospheric plasma (CAP), is an expanding field within plasma research. CAP has demonstrated remarkable versatility in diverse biological applications, including cancer treatment, wound healing, microorganism inactivation, and skin disease therapy. However, the precise mechanisms underlying the effects of CAP remain incompletely understood. The therapeutic effects of CAP are largely attributed to the generation of reactive oxygen and nitrogen species (RONS), which play a crucial role in the biological responses induced by CAP. Specifically, RONS produced during CAP treatment have the ability to chemically modify cell membranes and membrane proteins, causing nitro-oxidative stress, thereby leading to changes in membrane permeability and disruption of cellular processes. To gain atomic-level insights into these interactions, non-reactive molecular dynamics (MD) simulations have emerged as a valuable tool. These simulations facilitate the examination of larger-scale system dynamics, including protein-protein and protein-membrane interactions. In this comprehensive review, we focus on the applications of non-reactive MD simulations in studying the effects of CAP on cellular components and interactions at the atomic level, providing a detailed overview of the potential of CAP in medicine. We also review the results of other MD studies that are not related to plasma medicine but explore the effects of nitro-oxidative stress on cellular components and are therefore important for a broader understanding of the underlying processes.

Current Status and Future Trends of Cold Atmospheric Plasma as an Oncotherapy

Cold atmospheric plasma (CAP), a redox modulation tool, is capable of inhibiting a wide spectrum of cancers and has thus been proposed as an emerging onco-therapy. However, with incremental successes consecutively reported on the anticancer efficacy of CAP, no consensus has been made on the types of tumours sensitive to CAP due to the different intrinsic characteristics of the cells and the heterogeneous design of CAP devices and their parameter configurations. These factors have substantially hindered the clinical use of CAP as an oncotherapy. It is thus imperative to clarify the tumour types responsive to CAP, the experimental models available for CAP-associated investigations, CAP administration strategies and the mechanisms by which CAP exerts its anticancer effects with the aim of identifying important yet less studied areas to accelerate the process of translating CAP into clinical use and fostering the field of plasma oncology.

Can Bee Venom Be Used as Anticancer Agent in Modern Medicine?

Honey bee venom in its composition contains many biologically active peptides and enzymes that are effective in the fight against diseases of various etiologies. The history of the use of bee venom for medicinal purposes dates back thousands of years. There are many reports in the literature on the pharmacological properties of bee venom and/or its main components, e.g., anti-arthritic, anti-inflammatory, anti-microbial or neuroprotective properties. In addition, both crude venom and melittin exhibit cytotoxic activity against a wide range of tumor cells, with significant anti-metastatic activity in pre-clinical studies. Due to the constantly increasing incidence of cancer, the development of new therapeutic strategies in oncology is a particular challenge for modern medicine. A review paper discusses the various properties of bee venom with an emphasis on its anticancer properties. For this purpose, the PubMed database was searched, and publications related to "bee", "venom", "cancer" from the last 10 years were selected.

An Updated Review Summarizing the Anticancer Efficacy of Melittin from Bee Venom in Several Models of Human Cancers

Apitherapy (using bee products) has gained broad recognition in cancer therapeutics globally. Honeybee venom has a broad range of biological potential, and its utilization is rapidly emerging in apitherapy. Bee products have significant potential to strengthen the immune system and improve human health. Thus, this review is targeted toward recapitulating the chemo-preventive potential of melittin (MEL), which constitutes a substantial portion of honeybee venom. Honeybee venom (apitoxin) is produced in the venom gland of the honeybee abdomen, and adult bees utilize it as a primary colony defense mechanism. Apitoxin comprises numerous biologically active compounds, including peptides, enzymes, amines, amino acids, phospholipids, minerals, carbohydrates, and volatile components. We are mainly focused on exploring the potential of melittin (a peptide component) of bee venom that has shown promising potential in the treatment of several human cancers, including breast, stomach, lung, prostate, ovary, kidney, colon, gastric, esophageal, cervical cancers, melanoma, osteosarcoma, and hepatocellular carcinoma. This review has summarized all potential studies related to the anticancerous efficacy of melittin (apitoxin), its formulations, conjugates, and nano-formulations against several human carcinomas, which would further pave the way for future researchers in developing potent drugs for cancer management.

Effect of Melittin Complexes with Graphene and Graphene Oxide on Triple-Negative Breast Cancer Tumors Grown on Chicken Embryo Chorioallantoic Membrane

One of the components of bee venom is melittin (M), which has strong lysing properties on membranes. M has high toxicity to cancer cells, but it also affects healthy cells, making it necessary to use methods for targeted delivery to ensure treatment. This research is a continuation of previous studies using graphene nanomaterials as M carriers to breast cancer cells. The studies described below are conducted on a more organized biological structure than what is found in vitro cells, namely, cancerous tumors grown on a chicken embryo chorioallantoic membrane. Caspase 3 and 8 levels are analyzed, and the level of oxidative stress markers and changes in protein expression for cytokines are examined. The results show that M complexes with nanomaterials reduce the level of oxidative stress more than M alone does, but the use of graphene (GN) as a carrier increases the level of DNA damage to a greater extent than the increase caused by M alone. An analysis of cytokine levels shows that the use of the M and GN complex increases the level of proteins responsible for inhibiting tumor progression to a greater extent than the increase occasioned by a complex with graphene oxide (GO). The results suggest that the use of GN as an M carrier may increase the toxic effect of M on structures located inside a cell.

Recent advances in cold atmospheric plasma (CAP) for breast cancer therapy

The serious problems of conventional breast cancer therapy strategies such as drug resistance, severe side effects, and lack of selectivity prompted the development of various cold atmospheric plasma (CAP) devices. Due to its advanced technology, CAP can produce a unique environment rich in reactive oxygen and nitrogen species (RONS), photons, charged ions, and an electric field, making it a promising revolutionary platform for cancer therapy. Despite substantial technological successes, CAP-based therapeutic systems are encounter with distinct limitations, including low control of the generated RONS, poor knowledge about its anticancer mechanisms, and challenges concerning designing, manufacturing, clinical translation, and commercialization, which must be resolved. The latest developments in CAP-based therapeutic systems for breast cancer treatment are discussed in this review. More significantly, the integration of CAP-based medicine approaches with other breast cancer therapies, including chemo- and nanotherapy is thoroughly addressed.

Recent advances of bioactive proteins/polypeptides in the treatment of breast cancer

Proteins do not only serve as nutrients to fulfill the demand for food, but also are used as a source of bioactive proteins/polypeptides for regulating physical functions and promoting physical health. Female breast cancer has the highest incidence in the world and is a serious threat to women's health. Bioactive proteins/polypeptides exert strong anti-tumor effects and exhibit inhibition of multiple breast cancer cells. This review discussed the suppressing effects of bioactive proteins/polypeptides on breast cancer in vitro and in vivo, and their mechanisms of migration and invasion inhibition, apoptosis induction, and cell cycle arrest. This may contribute to providing a basis for the development of bioactive proteins/polypeptides for the treatment of breast cancer.

Graphical abstract

In ovo model in cancer research and tumor immunology

Considering cancer not only as malignant cells on their own but as a complex disease in which tumor cells interact and communicate with their microenvironment has motivated the establishment of clinically relevant 3D models in past years. Technological advances gave rise to novel bioengineered models, improved organoid systems, and microfabrication approaches, increasing scientific importance in preclinical research. Notwithstanding, mammalian in vivo models remain closest to mimic the patient’s situation but are limited by cost, time, and ethical constraints. Herein, the in ovo model bridges the gap as an advanced model for basic and translational cancer research without the need for ethical approval. With the avian embryo being a naturally immunodeficient host, tumor cells and primary tissues can be engrafted on the vascularized chorioallantoic membrane (CAM) with high efficiencies regardless of species-specific restrictions. The extraembryonic membranes are connected to the embryo through a continuous circulatory system, readily accessible for manipulation or longitudinal monitoring of tumor growth, metastasis, angiogenesis, and matrix remodeling. However, its applicability in immunoncological research is largely underexplored. Dual engrafting of malignant and immune cells could provide a platform to study tumor-immune cell interactions in a complex, heterogenic and dynamic microenvironment with high reproducibility. With some caveats to keep in mind, versatile methods for in and ex ovo monitoring of cellular and molecular dynamics already established in ovo are applicable alike. In this view, the present review aims to emphasize and discuss opportunities and limitations of the chicken embryo model for pre-clinical research in cancer and cancer immunology.

Possible Synergies of Nanomaterial-Assisted Tissue Regeneration in Plasma Medicine: Mechanisms and Safety Concerns

Cold atmospheric plasma and nanomedicine originally emerged as individual domains, but are increasingly applied in combination with each other. Most research is performed in the context of cancer treatment, with only little focus yet on the possible synergies. Many questions remain on the potential of this promising hybrid technology, particularly regarding regenerative medicine and tissue engineering. In this perspective article, we therefore start from the fundamental mechanisms in the individual technologies, in order to envision possible synergies for wound healing and tissue recovery, as well as research strategies to discover and optimize them. Among these strategies, we demonstrate how cold plasmas and nanomaterials can enhance each other's strengths and overcome each other's limitations. The parallels with cancer research, biotechnology and plasma surface modification further serve as inspiration for the envisioned synergies in tissue regeneration. The discovery and optimization of synergies may also be realized based on a profound understanding of the underlying redox- and field-related biological processes. Finally, we emphasize the toxicity concerns in plasma and nanomedicine, which may be partly remediated by their combination, but also partly amplified. A widespread use of standardized protocols and materials is therefore strongly recommended, to ensure both a fast and safe clinical implementation.

Pharmacological effects and mechanisms of bee venom and its main components: Recent progress and perspective

Bee venom (BV), a type of defensive venom, has been confirmed to have favorable activities, such as anti-tumor, neuroprotective, anti-inflammatory, analgesic, anti-infectivity effects, etc. This study reviewed the recent progress on the pharmacological effects and mechanisms of BV and its main components against cancer, neurological disorders, inflammatory diseases, pain, microbial diseases, liver, kidney, lung and muscle injury, and other diseases in literature during the years 2018-2021. The related target proteins of BV and its main components against the diseases include Akt, mTOR, JNK, Wnt-5α, HIF-1α, NF-κB, JAK2, Nrf2, BDNF, Smad2/3, AMPK, and so on, which are referring to PI3K/Akt/mTOR, MAPK, Wnt/β-catenin, HIF-1α, NF-κB, JAK/STAT, Nrf2/HO-1, TrkB/CREB/BDNF, TGF-β/Smad2/3, and AMPK signaling pathways, etc. Further, with the reported targets, the potential effects and mechanisms on diseases were bioinformatically predicted via Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, disease ontology semantic and enrichment (DOSE) and protein-protein interaction (PPI) analyses. This review provides new insights into the therapeutic effects and mechanisms of BV and its main components on diseases.

Plasma activated medium prepared by a bipolar microsecond-pulsed atmospheric pressure plasma jet array induces mitochondria-mediated apoptosis in human cervical cancer cells

Plasma activated medium (PAM) was prepared by a bipolar microsecond-pulsed atmospheric pressure plasma jet (APPJ) array source and was utilized for cancer cell treatment. APPJ array-produced plasma were characterized. APPJ array treatment of three different solutions (deionized water (DW), HBSS (serum-free Hanks’ balanced salt solution), and DMEM (Dulbecco’s Modified Eagle Medium) + 10% FBS (fetal bovine serum)) were performed to induce the changes in the concentration of reactive oxygen and nitrogen species (RONS) as functions of the operating parameters. Human cervical cancer cells (HeLa) injected with plasma-treated media were investigated for changes in cell viability using MTT assay. It was observed that PAM-induced ROS can regulate the protein expression associated with mitochondria, and PAM causes apoptosis through Cyto C/JNK/p38 signaling on human cervical cancer cells.

Anticancer Activity of Bee Venom Components against Breast Cancer

While the survival rate has increased due to treatments for breast cancer, the quality of life has decreased because of the side effects of chemotherapy. Various toxins are being developed as alternative breast cancer treatments, and bee venom is drawing attention as one of them. We analyzed the effect of bee venom and its components on breast cancer cells and reviewed the mechanism underlying the anticancer effects of bee venom. Data up to March 2022 were searched from PubMed, EMBASE, OASIS, KISS, and Science Direct online databases, and studies that met the inclusion criteria were reviewed. Among 612 studies, 11 were selected for this research. Diverse drugs were administered, including crude bee venom, melittin, phospholipase A2, and their complexes. All drugs reduced the number of breast cancer cells in proportion to the dose and time. The mechanisms of anticancer effects included cytotoxicity, apoptosis, cell targeting, gene expression regulation, and cell lysis. Summarily, bee venom and its components exert anticancer effects on human breast cancer cells. Depending on the mechanisms of anticancer effects, side effects are expected to be reduced by using various vehicles. Bee venom and its components have the potential to prevent and treat breast cancer in the future.

Modulating the Antioxidant Response for Better Oxidative Stress-Inducing Therapies: How to Take Advantage of Two Sides of the Same Medal?

Oxidative stress-inducing therapies are characterized as a specific treatment that involves the production of reactive oxygen and nitrogen species (RONS) by external or internal sources. To protect cells against oxidative stress, cells have evolved a strong antioxidant defense system to either prevent RONS formation or scavenge them. The maintenance of the redox balance ensures signal transduction, development, cell proliferation, regulation of the mechanisms of cell death, among others. Oxidative stress can beneficially be used to treat several diseases such as neurodegenerative disorders, heart disease, cancer, and other diseases by regulating the antioxidant system. Understanding the mechanisms of various endogenous antioxidant systems can increase the therapeutic efficacy of oxidative stress-based therapies, leading to clinical success in medical treatment. This review deals with the recent novel findings of various cellular endogenous antioxidant responses behind oxidative stress, highlighting their implication in various human diseases, such as ulcers, skin pathologies, oncology, and viral infections such as SARS-CoV-2.

Synergistic effect of plasma-activated medium and novel indirubin derivatives on human skin cancer cells by activation of the AhR pathway

Due to the increasing number of human skin cancers and the limited effectiveness of therapies, research into innovative therapeutic approaches is of enormous clinical interest. In recent years, the use of cold atmospheric pressure plasma has become increasingly important as anti-cancer therapy. The combination of plasma with small molecules offers the potential of an effective, tumour-specific, targeted therapy. The synthesised glycosylated and non glycosylated thia-analogous indirubin derivatives KD87 and KD88, respectively, were first to be investigated for their pharmaceutical efficacy in comparison with Indirubin-3'-monoxime (I3M) on human melanoma (A375) and squamous cell carcinoma (A431) cells. In combinatorial studies with plasma-activated medium (PAM) and KD87 we determined significantly decreased cell viability and cell adhesion. Cell cycle analyses revealed a marked G2/M arrest by PAM and a clear apoptotic effect by the glycosylated indirubin derivative KD87 in both cell lines and thus a synergistic anti-cancer effect. I3M had a pro-apoptotic effect only in A431 cells, so we hypothesize a different mode of action of the indirubin derivatives in the two skin cancer cells, possibly due to a different level of the aryl hydrocarbon receptor and an activation of this pathway by nuclear translocation of this receptor and subsequent activation of gene expression.

Cold Atmospheric Plasma Does Not Affect Stellate Cells Phenotype in Pancreatic Cancer Tissue in Ovo

Pancreatic ductal adenocarcinoma (PDAC) is a challenging neoplastic disease, mainly due to the development of resistance to radio- and chemotherapy. Cold atmospheric plasma (CAP) is an alternative technology that can eliminate cancer cells through oxidative damage, as shown in vitro, in ovo, and in vivo. However, how CAP affects the pancreatic stellate cells (PSCs), key players in the invasion and metastasis of PDAC, is poorly understood. This study aims to determine the effect of an anti-PDAC CAP treatment on PSCs tissue developed in ovo using mono- and co-cultures of RLT-PSC (PSCs) and Mia PaCa-2 cells (PDAC). We measured tissue reduction upon CAP treatment and mRNA expression of PSC activation markers and extracellular matrix (ECM) remodelling factors via qRT-PCR. Protein expression of selected markers was confirmed via immunohistochemistry. CAP inhibited growth in Mia PaCa-2 and co-cultured tissue, but its effectiveness was reduced in the latter, which correlates with reduced ki67 levels. CAP did not alter the mRNA expression of PSC activation and ECM remodelling markers. No changes in MMP2 and MMP9 expression were observed in RLT-PSCs, but small changes were observed in Mia PaCa-2 cells. Our findings support the ability of CAP to eliminate PDAC cells, without altering the PSCs.

Cold Physical Plasma in Cancer Therapy: Mechanisms, Signaling, and Immunity

Despite recent advances in therapy, cancer still is a devastating and life-threatening disease, motivating novel research lines in oncology. Cold physical plasma, a partially ionized gas, is a new modality in cancer research. Physical plasma produces various physicochemical factors, primarily reactive oxygen and nitrogen species (ROS/RNS), causing cancer cell death when supplied at supraphysiological concentrations. This review outlines the biomedical consequences of plasma treatment in experimental cancer therapy, including cell death modalities. It also summarizes current knowledge on intracellular signaling pathways triggered by plasma treatment to induce cancer cell death. Besides the inactivation of tumor cells, an equally important aspect is the inflammatory context in which cell death occurs to suppress or promote the responses of immune cells. This is mainly governed by the release of damage-associated molecular patterns (DAMPs) to provoke immunogenic cancer cell death (ICD) that, in turn, activates cells of the innate immune system to promote adaptive antitumor immunity. The pivotal role of the immune system in cancer treatment, in general, is highlighted by many clinical trials and success stories on using checkpoint immunotherapy. Hence, the potential of plasma treatment to induce ICD in tumor cells to promote immunity targeting cancer lesions systemically is also discussed.

Combining Nanotechnology and Gas Plasma as an Emerging Platform for Cancer Therapy: Mechanism and Therapeutic Implication

Nanomedicine and plasma medicine are innovative and multidisciplinary research fields aiming to employ nanotechnology and gas plasma to improve health-related treatments. Especially cancer treatment has been in the focus of both approaches because clinical response rates with traditional methods that remain improvable for many types of tumor entities. Here, we discuss the recent progress of nanotechnology and gas plasma independently as well as in the concomitant modality of nanoplasma as multimodal platforms with unique capabilities for addressing various therapeutic issues in oncological research. The main features, delivery vehicles, and nexus between reactivity and therapeutic outcomes of nanoparticles and the processes, efficacy, and mechanisms of gas plasma are examined. Especially that the unique feature of gas plasma technology, the local and temporally controlled deposition of a plethora of reactive oxygen, and nitrogen species released simultaneously might be a suitable additive treatment to the use of systemic nanotechnology therapy approaches. Finally, we focus on the convergence of plasma and nanotechnology to provide a suitable strategy that may lead to the required therapeutic outcomes.

Bee Venom Melittin Disintegrates the Respiration of Mitochondria in Healthy Cells and Lymphoblasts, and Induces the Formation of Non-Bilayer Structures in Model Inner Mitochondrial Membranes

In this paper, we examined the effects of melittin, a bee venom membrane-active peptide, on mitochondrial respiration and cell viability of healthy human lymphocytes (HHL) and Jurkat cells, as well as on lymphoblasts from acute human T cell leukemia. The viability of melittin-treated cells was related to changes in O₂ consumption and in the respiratory control index (RCI) of mitochondria isolated from melittin-pretreated cells as well as of mitochondria first isolated from cells and then directly treated with melittin. It was shown that melittin is three times more cytotoxic to Jurkat cells than to HHL, but O₂ consumption and RCI values of mitochondria from both cell types were equally affected by melittin when melittin was directly added to mitochondria. To elucidate the molecular mechanism of melittin’s cytotoxicity to healthy and cancer cells, the effects of melittin on lipid-packing and on the dynamics in model plasma membranes of healthy and cancer cells, as well as of the inner mitochondrial membrane, were studied by EPR spin probes. The affinity of melittin binding to phosphatidylcholine, phosphatidylserine, phosphatidic acid and cardiolipin, and binding sites of phospholipids on the surface of melittin were studied by ³¹P-NMR, native PAGE and AutoDock modeling. It is suggested that the melittin-induced decline of mitochondrial bioenergetics contributes primarily to cell death; the higher cytotoxicity of melittin to cancer cells is attributed to its increased permeability through the plasma membrane.

Applications and evolution of melittin, the quintessential membrane active peptide

Melittin, the main venom component of the European Honeybee, is a cationic linear peptide-amide of 26 amino acid residues with the sequence: GIGAVLKVLTTGLPALISWIKRKRQQ-NH₂. Melittin binds to lipid bilayer membranes, folds into amphipathic α-helical secondary structure and disrupts the permeability barrier. Since melittin was first described, a remarkable array of activities and potential applications in biology and medicine have been described. Melittin is also a favorite model system for biophysicists to study the structure, folding and function of peptides and proteins in membranes. Melittin has also been used as a template for the evolution of new activities in membranes. Here we overview the rich history of scientific research into the many activities of melittin and outline exciting future applications.

α-Mangostin Nanoparticles Cytotoxicity and Cell Death Modalities in Breast Cancer Cell Lines

α-Mangostin (AMG) is a potent anticancer xanthone that was discovered in mangosteen (Garcinia mangostana Linn.). AMG possesses the highest opportunity for chemopreventive and chemotherapeutic therapy. AMG inhibits every step in the process of carcinogenesis. AMG suppressed multiple breast cancer (BC) cell proliferation and apoptosis by decreasing the creation of cancerous compounds. Accumulating BC abnormalities and their associated molecular signaling pathways promotes novel treatment strategies. Chemotherapy is a commonly used treatment; due to the possibility of unpleasant side effects and multidrug resistance, there has been substantial progress in searching for alternative solutions, including the use of plant-derived natural chemicals. Due to the limitations of conventional cancer therapy, nanotechnology provides hope for effective and efficient cancer diagnosis and treatment. Nanotechnology enables the delivery of nanoparticles and increased solubility of drugs and drug targeting, resulting in increased cytotoxicity and cell death during BC treatment. This review summarizes the progress and development of AMG’s cytotoxicity and the mechanism of death BC cells. The combination of natural medicine and nanotechnology into a synergistic capital will provide various benefits. This information will aid in the development of AMG nanoparticle preparations and may open up new avenues for discovering an effective BC treatment.

Plasma-activated thermosensitive biogel as an exogenous ROS carrier for post-surgical treatment of cancer

Post-surgical residual tumor cells are the primary cause of relapse and progression of cancer but unfortunately, there are limited therapeutic options. In this work, a fillable plasma-activated biogel is produced on a thermosensitive biogel [(Poly-DL-lactide)-(poly-ethylene glycol)-(poly-DL-lactide), PLEL] with the aid of a discharge plasma for local post-operative treatment of cancer. In vivo data show that the plasma-activated PLEL biogel (PAPB) eliminates residual tumor tissues after removal surgery and also inhibits in situ recurrence while showing no evident systemic toxicity. Moreover, the PAPB possesses excellent storage capability, allows for slow release of plasma-generated reactive oxygen species (ROS), and exhibits good ROS-mediated anticancer effects in vitro. Our results reveal that the novel plasma-activated biogel is an effective therapeutic agent for local post-operative treatment of cancer.

Novel Anticancer and Treatment Sensitizing Compounds against Pancreatic Cancer

The isolation of chemical compounds from natural origins for medical application has played an important role in modern medicine with a range of novel treatments having emerged from various natural forms over the past decades. Natural compounds have been exploited for their antioxidant, antimicrobial and antitumor capabilities. Specifically, 60% of today's anticancer drugs originate from natural sources. Moreover, the combination of synthetic and natural treatments has shown applications for (i) reduced side effects, (ii) treatment sensitization and (iii) reduction in treatment resistance. This review aims to collate novel and natural compounds that are being explored for their preclinical anticancer, chemosensitizing and radiosensitizing effects on Pancreatic Ductal Adenocarcinoma (PDAC), which is a lethal disease with current treatments being inefficient and causing serve side effects. Two key points are highlighted by this work: (i) the availability of a range of natural compounds for potentially new therapeutic approaches for PDAC, (ii) potential synergetic impact of natural compounds with advanced chemo- and radio-therapeutic modalities for PDAC.

Open-Air Cold Plasma Device Leads to Selective Tumor Cell Cytotoxicity

The need for effective and safe therapies for cancer is growing as aging is modifying its epidemiology. Cold atmospheric plasma (CAP) has gained attention as a potential anti-tumor therapy. CAP is a gas with enough energy to ionize a significant fraction of its constituent particles, forming equal numbers of positive ions and electrons. Timely-resolved output voltage measurement, emission spectroscopy, and quantification of reactive species (RS) in plasma-activated media (PAM) were performed to characterize the physical and chemical properties of plasma. To assess the cytotoxicity of cold atmospheric plasma in human tumors, different cell lines were cultured, plated, and exposed to CAP, followed by MTT and SRB colorimetric assays 24 h later. Human fibroblasts, phenotypically normal cells, were processed similarly. Plasma cytotoxicity was higher in cells of breast cancer, urinary bladder cancer, osteosarcoma, lung cancer, melanoma, and endometrial cancer. Cytotoxicity was time-dependent and possibly related to the increased production of hydrogen peroxide in the exposed medium. Sixty seconds of CAP exposure renders selective effects, preserving the viability of fibroblast cells. These results point to the importance of conducting further studies of the therapy with plasma.

Anti-PD-1 Immunotherapy and Bee Venom for Relapsed and Refractory Liposarcoma: A Case Report

Cancer immunotherapies, including immune checkpoint inhibitors, elicit long-term clinical responses but many cancer patients do not respond. Intensive efforts are therefore underway to identify additional immune pathways that may be modulated to enhance the efficacy of existing immunotherapies. Bee venom strongly stimulates the immune system, and is used as a complementary therapy to treat cancer pain in patients with advanced tumors in China. Bee venom contains several allergenic protease inhibitors and peptides. It triggers hypersensitivity reactions; that is, it is an immune system agonist. The generation of a spontaneous T cell response against tumor-associated antigens requires innate immune activation; this drives type I interferon production. We report a patient with a relapsed and refractory liposarcoma who had undergone several operations, chemotherapies, and radiotherapies. The tumor was large. The patient had attained the maximum radiation exposure dose. The tumor was resistant to chemotherapy and was infiltrating the pericardium, lungs, and diaphragm. The patient was a poor candidate for resection. He thus received apitherapy (a combination of bee venom and acupuncture) to control pain; then apatinib (an anti-angiogenic drug) was given to inhibit tumor growth but was terminated early because the patient could not tolerate the side effects. Subsequently, a programmed death 1 inhibitor was combined with apitherapy. Bee venom served as an innate immune system agonist promoting immune cell priming and recruitment in the tumor microenvironment. The patient was finally able to undergo radical liposarcoma resection, and no evidence of recurrence was found at re-examination 16 months after surgery.

Cold Atmospheric Plasma Increases Temozolomide Sensitivity of Three-Dimensional Glioblastoma Spheroids via Oxidative Stress-Mediated DNA Damage

Simple Summary

Cold atmospheric plasma (CAP) is gaining increasing interest for cancer treatment, for a wide range of cancer types. The studies performed with CAP as a standalone treatment modality serve as evidence that it can also be a suitable candidate for combination therapy. Temozolomide (TMZ) is used as the gold standard drug for glioblastoma treatment, one of the most aggressive malignant brain tumors in adults that remains incurable despite treatment advances. In this study, we explore whether CAP, a cocktail of reactive oxygen and nitrogen species, can amplify the cytotoxic effect on both TMZ-sensitive and TMZ-resistant glioblastoma multiforme (GBM) in three-dimensional tumor-like tissues through inhibiting the glutathione (GSH)/ glutathione peroxidase 4 (GPX4) antioxidant machinery, which can further lead to DNA damage.

Abstract

Glioblastoma multiforme (GBM) is the most frequent and aggressive primary malignant brain tumor in adults. Current standard radiotherapy and adjuvant chemotherapy with the alkylating agent temozolomide (TMZ) yield poor clinical outcome. This is due to the stem-like properties of tumor cells and genetic abnormalities in GBM, which contribute to resistance to TMZ and progression. In this study, we used cold atmospheric plasma (CAP) to enhance the sensitivity to TMZ through inhibition of antioxidant signaling (linked to TMZ resistance). We demonstrate that CAP indeed enhances the cytotoxicity of TMZ by targeting the antioxidant specific glutathione (GSH)/glutathione peroxidase 4 (GPX4) signaling. We optimized the threshold concentration of TMZ on five different GBM cell lines (U251, LN18, LN229, U87-MG and T98G). We combined TMZ with CAP and tested it on both TMZ-sensitive (U251, LN18 and LN229) and TMZ-resistant (U87-MG and T98G) cell lines using two-dimensional cell cultures. Subsequently, we used a three-dimensional spheroid model for the U251 (TMZ-sensitive) and U87-MG and T98G (TMZ-resistant) cells. The sensitivity of TMZ was enhanced, i.e., higher cytotoxicity and spheroid shrinkage was obtained when TMZ and CAP were administered together. We attribute the anticancer properties to the release of intracellular reactive oxygen species, through inhibiting the GSH/GPX4 antioxidant machinery, which can lead to DNA damage. Overall, our findings suggest that the combination of CAP with TMZ is a promising combination therapy to enhance the efficacy of TMZ towards the treatment of GBM spheroids.

Physical plasma-derived oxidants sensitize pancreatic cancer cells to ferroptotic cell death

Despite modern therapeutic advances, the survival prospects of pancreatic cancer patients remain poor, due to chemoresistance and dysregulated oncogenic kinase signaling networks. We applied a novel kinome activity-mapping approach using biological peptide targets as phospho-sensors to identify vulnerable kinase dependencies for therapy sensitization by physical plasma. Ser/Thr-kinome specific activity changes were mapped upon induction of ferroptotic cell death in pancreatic tumor cells exposed to reactive oxygen and nitrogen species of plasma-treated water (PTW). This revealed a broad kinome activity response involving the CAMK, the AGC and CMGC family of kinases. This systems-level kinome network response supports stress adaptive switches between chemoresistant anti-oxidant responses of Kelch-like ECH-associated protein 1 (KEAP1)/Heme Oxygenase 1 (HMOX1) and ferroptotic cell death sensitization upon suppression of Nuclear factor (erythroid derived 2)-like 2 (NRF2) and Glutathione peroxidase 4 (GPX4). This is further supported by ex vivo experiments in the chicken chorioallantoic membrane assay, showing decreased GPX4 and Glutathione (GSH) expression as well as increased lipid peroxidation, along with suppressed BxPC-3 tumor growth in response to PTW. Taken all together, we demonstrate that plasma treated water-derived oxidants sensitize pancreatic cancer cells to ferroptotic cell death by targeting a NRF2-HMOX1-GPX4 specific kinase signaling network.

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.

Cold Atmospheric Plasma: A New Strategy Based Primarily on Oxidative Stress for Osteosarcoma Therapy

Osteosarcoma is the most common primary bone tumor, and its first line of treatment presents a high failure rate. The 5-year survival for children and teenagers with osteosarcoma is 70% (if diagnosed before it has metastasized) or 20% (if spread at the time of diagnosis), stressing the need for novel therapies. Recently, cold atmospheric plasmas (ionized gases consisting of UV-Vis radiation, electromagnetic fields and a great variety of reactive species) and plasma-treated liquids have been shown to have the potential to selectively eliminate cancer cells in different tumors through an oxidative stress-dependent mechanism. In this work, we review the current state of the art in cold plasma therapy for osteosarcoma. Specifically, we emphasize the mechanisms unveiled thus far regarding the action of plasmas on osteosarcoma. Finally, we review current and potential future approaches, emphasizing the most critical challenges for the development of osteosarcoma therapies based on this emerging technique.

Cytotoxic and Pro-Apoptotic Effects of a Sub-Toxic Concentration of Fluvastatin on OVCAR3 Ovarian Cancer Cells After its Optimized Formulation to Melittin Nano-Conjugates

Fluvastatin (FLV) is a hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitor often used to lower total and low-density lipoprotein (LDL) cholesterol and for the prevention of adverse cardiovascular events. This drug as well as melittin (MEL), the major component of honeybee venom (Apis mellifera), has shown antineoplastic activity, then representing promising approaches for cancer therapy. However, adverse effects related to the use of FLV and MEL have been reported and very few studies have been carried out to obtain an optimized formulation allowing for combining the two drugs and then maximizing the anticancer activity, then minimizing the needed dosage. In the present study, an optimized formulation in terms of minimized particle size and maximized zeta potential was investigated for its cytotoxic potential in human OVCAR3 ovarian cancer cells. FLV-MEL nano-conjugates, containing a sub-toxic concentration of drug, demonstrated an improved cytotoxic potential (IC50 = 2.5 µM), about 18-fold lower, compared to the free drug (IC50 = 45.7 µM). Cell cycle analysis studies demonstrated the significant inhibition of the OVCAR3 cells proliferation exerted by FLV-MEL nano-conjugates compared to all the other treatments, with a higher percentage of cells accumulating on G2/M and pre-G1 phases, paralleled by lower percentage of cells in G0/G1 and S phases. The synergistic antineoplastic activity of FLV and MEL combined in the optimized formula was also showed by the marked pronecrotic and pro-apoptotic activities, the latter mediated by the modulation of BAX/BCL-2 ratio in favor of BAX. Our optimized FLV-MEL formulation might therefore represents a novel path for the development of specific and more effective antineoplastic drugs directed against ovarian cancer.

Venom peptides in cancer therapy: An updated review on cellular and molecular aspects

Based on the high incidence and mortality rates of cancer, its therapy remains one of the most vital challenges in the field of medicine. Consequently, enhancing the efficacy of currently applied treatments and finding novel strategies are of great importance for cancer treatment. Venoms are important sources of a variety of bioactive compounds including salts, small molecules, macromolecules, proteins, and peptides that are defined as toxins. They can exhibit different pharmacological effects, and in recent years, their anti-tumor activities have gained significant attention. Several different compounds are responsible for the anti-tumor activity of venoms, and peptides are one of them. In the present review, we discuss the possible anti-tumor activities of venom peptides by highlighting molecular pathways and mechanisms through which these molecules can act effectively. Venom peptides can induce cell death in cancer cells and can substantially enhance the efficacy of chemotherapy and radiotherapy. Also, the venom peptides can mitigate the migration of cancer cells via suppression of angiogenesis and epithelial-to-mesenchymal transition. Notably, nanoparticles have been applied in enhancing the bioavailability of venom peptides and providing targeted delivery, thereby leading to their elevated anti-tumor activity and potential application for cancer therapy.

Plasma medicine: Opportunities for nanotechnology in a digital age

Advances in digital technologies have opened new opportunities for creating more reliable, time- and cost-effective, safer and mobile methods of diagnosing, managing and treating diseases. A few examples of advanced nano- and digital technologies are already FDA-approved for diagnosing and treating diseases. Plasma treatment is still emerging as a new healthcare technology, but it is showing a strong potential for treatment of many diseases including cancers and antimicrobial-resistant infections, with little or no adverse side effects. Here, we argue that with the ever-increasing complex healthcare challenges facing communities, including the ongoing COVID-19 pandemic, it is critical to consider combining unique properties of emerging healthcare technologies into a single multimodal treatment modality that could lead to unprecedented healthcare benefits. In this article, we focus on the healthcare opportunities created by establishing a nexus between plasma, nano- and digital technologies. We argue that the combination of plasma, nano- and digital technologies into a single multimodal healthcare package may significantly improve patient outcomes and comfort, and reduce the economic burden on community healthcare, as well as alleviate many problems related to overcrowded healthcare systems.

How Do mAbs Make Use of Complement to Kill Cancer Cells? The Role of Ca2

We examined the kinetics and mechanisms by which monoclonal antibodies (mAbs) utilize complement to rapidly kill targeted cancer cells. Based on results from flow cytometry, confocal microscopy and high-resolution digital imaging experiments, the general patterns which have emerged reveal cytotoxic activities mediated by substantial and lethal Ca2+ fluxes. The Ca2+ fluxes are common to the reported pathways that have been utilized by other toxins in killing nucleated cells. These reactions terminate in very high levels of cell killing, and based on these considerations, we suggest additional strategies to further enhance mAb-based targeting of cancer with complement.

Honeybee venom and melittin suppress growth factor receptor activation in HER2-enriched and triple-negative breast cancer

Despite decades of study, the molecular mechanisms and selectivity of the biomolecular components of honeybee (Apis mellifera) venom as anticancer agents remain largely unknown. Here, we demonstrate that honeybee venom and its major component melittin potently induce cell death, particularly in the aggressive triple-negative and HER2-enriched breast cancer subtypes. Honeybee venom and melittin suppress the activation of EGFR and HER2 by interfering with the phosphorylation of these receptors in the plasma membrane of breast carcinoma cells. Mutational studies reveal that a positively charged C-terminal melittin sequence mediates plasma membrane interaction and anticancer activity. Engineering of an RGD motif further enhances targeting of melittin to malignant cells with minimal toxicity to normal cells. Lastly, administration of melittin enhances the effect of docetaxel in suppressing breast tumor growth in an allograft model. Our work unveils a molecular mechanism underpinning the anticancer selectivity of melittin, and outlines treatment strategies to target aggressive breast cancers.

Plasma Treatment Limits Cutaneous Squamous Cell Carcinoma Development In Vitro and In Vivo

Cutaneous squamous cell carcinoma (SCC) is the most prevalent cancer worldwide, increasing the cost of healthcare services and with a high rate of morbidity. Its etiology is linked to chronic ultraviolet (UV) exposure that leads to malignant transformation of keratinocytes. Invasive growth and metastasis are severe consequences of this process. Therapy-resistant and highly aggressive SCC is frequently fatal, exemplifying the need for novel treatment strategies. Cold physical plasma is a partially ionized gas, expelling therapeutic doses of reactive oxygen and nitrogen species that were investigated for their anticancer capacity against SCC in vitro and SCC-like lesions in vivo. Using the kINPen argon plasma jet, a selective growth-reducing action of plasma treatment was identified in two SCC cell lines in 2D and 3D cultures. In vivo, plasma treatment limited the progression of UVB-induced SSC-like skin lesions and dermal degeneration without compromising lesional or non-lesional skin. In lesional tissue, this was associated with a decrease in cell proliferation and the antioxidant transcription factor Nrf2 following plasma treatment, while catalase expression was increased. Analysis of skin adjacent to the lesions and determination of global antioxidant parameters confirmed the local but not systemic action of the plasma anticancer therapy in vivo.

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

Tumours are complex systems formed by cellular (malignant, immune, and endothelial cells, fibroblasts) and acellular components (extracellular matrix (ECM) constituents and secreted factors). A close interplay between these factors, collectively called the tumour microenvironment, is required to respond appropriately to external cues and to determine the treatment outcome. Cold plasma (here referred as ‘plasma’) is an emerging anticancer technology that generates a unique cocktail of reactive oxygen and nitrogen species to eliminate cancerous cells via multiple mechanisms of action. While plasma is currently regarded as a local therapy, it can also modulate the mechanisms of cell-to-cell and cell-to-ECM communication, which could facilitate the propagation of its effect in tissue and distant sites. However, it is still largely unknown how the physical interactions occurring between cells and/or the ECM in the tumour microenvironment affect the plasma therapy outcome. In this review, we discuss the effect of plasma on cell-to-cell and cell-to-ECM communication in the context of the tumour microenvironment and suggest new avenues of research to advance our knowledge in the field. Furthermore, we revise the relevant state-of-the-art in three-dimensional in vitro models that could be used to analyse cell-to-cell and cell-to-ECM communication and further strengthen our understanding of the effect of plasma in solid tumours.