Molecular basis underlying the biological effects elicited by extremely low-frequency magnetic field (ELF-MF) on neuroblastoma cells

Effects of extremely low-frequency magnetic fields on human MDA-MB-231 breast cancer cells: proteomic characterization

Extremely low-frequency electromagnetic fields (ELF-MF) can modify the cell viability and regulatory processes of some cell types, including breast cancer cells. Breast cancer is a multifactorial disease where a role for ELF-MF cannot be excluded. ELF-MF may influence the biological properties of breast cells through molecular mechanisms and signaling pathways that are still unclear. This study analyzed the changes in the cell viability, cellular morphology, oxidative stress response and alteration of proteomic profile in breast cancer cells (MDA-MB-231) exposed to ELF-MF (50 Hz, 1 mT for 4 h). Non-tumorigenic human breast cells (MCF-10A) were used as control cells. Exposed MDA-MB-231 breast cancer cells increased their viability and live cell number and showed a higher density and length of filopodia compared with the unexposed cells. In addition, ELF-MF induced an increase of the mitochondrial ROS levels and an alteration of mitochondrial morphology. Proteomic data analysis showed that ELF-MF altered the expression of 328 proteins in MDA-MB-231 cells and of 242 proteins in MCF-10A cells. Gene Ontology term enrichment analysis demonstrated that in both cell lines ELF-MF exposure up-regulated the genes enriched in "focal adhesion" and "mitochondrion". The ELF-MF exposure decreased the adhesive properties of MDA-MB-231 cells and increased the migration and invasion cell abilities. At the same time, proteomic analysis, confirmed by Real Time PCR, revealed that transcription factors associated with cellular reprogramming were upregulated in MDA-MB-231 cells and downregulated in MCF-10A cells after ELF-MF exposure. MDA-MB-231 breast cancer cells exposed to 1 mT 50 Hz ELF-MF showed modifications in proteomic profile together with changes in cell viability, cellular morphology, oxidative stress response, adhesion, migration and invasion cell abilities. The main signaling pathways involved were relative to focal adhesion, mitochondrion and cellular reprogramming.

Role of hydrogen sulfide in subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is a common acute and severe disease worldwide, which imposes a heavy burden on families and society. However, the current therapeutic strategies for SAH are unsatisfactory. Hydrogen sulfide (H₂ S), as the third gas signaling molecule after carbon monoxide and nitric oxide, has been widely studied recently. There is growing evidence that H₂ S has a promising future in the treatment of central nervous system diseases. In this review, we focus on the effects of H₂ S in experimental SAH and elucidate the underlying mechanisms. We demonstrate that H₂ S has neuroprotective effects and significantly reduces secondary damage caused by SAH via antioxidant, antiinflammatory, and antiapoptosis mechanisms, and by alleviating cerebral edema and vasospasm. Based on these findings, we believe that H₂ S has great potential in the treatment of SAH and warrants further study to promote its early clinical application.

An Extremely Low-Frequency Vortex Magnetic Field Modifies Protein Expression, Rearranges the Cytoskeleton, and Induces Apoptosis of a Human Neuroblastoma Cell Line

Homogeneous extremely low-frequency electromagnetic fields (ELF-EMFs) alter biological phenomena, including the cell phenotype and proliferation rate. Heterogenous vortex magnetic fields (VMFs), a new approach of exposure to magnetic fields, induce systematic movements on charged biomolecules from target cells; however, the effect of VMFs on living systems remains uncertain. Here, we designed, constructed, and characterized an ELF-VMF-modified Rodin's coil to expose SH-SY5Y cells. Samples were analyzed by performing 2D-differential-gel electrophoresis, identified by MALDI-TOF/TOF, validated by western blotting, and characterized by confocal microscopy. A total of 106 protein spots were differentially expressed; 40 spots were downregulated and 66 were upregulated in the exposed cell proteome, compared to the control cell proteome. The identified spots are associated with cytoskeleton and cell viability proteins, and according to the protein-protein interaction network, a significant interaction among them was found. Our data revealed a decrease in cell survival associated with apoptotic cells without effects on the cell cycle, as well as evident changes in the cytoskeleton. We demonstrated that ELF-VMFs, at a specific frequency and exposure time, alter the cell proteome and structurally affect the target cells. This is the first report showing that VMF application might be a versatile system for testing different hypotheses in living systems, using appropriate exposure parameters.© 2022 Bioelectromagnetics Society.

Alteration of Serum Proteome in Levo-Thyroxine-Euthyroid Thyroidectomized Patients

The monotherapy with levo-thyroxine (LT4) is the treatment of choice for patients with hypothyroidism after thyroidectomy. However, many athyreotic LT4-treated patients with thyroid hormones in the physiological range experience hypothyroid-like symptoms, showing post-operative, statistically significant lower FT3 levels with respect to that before total thyroidectomy. Since we hypothesized that the lower plasmatic FT3 levels observed in this subgroup could be associated with tissue hypothyroidism, here we compared, by a preliminary proteomic analysis, eight sera of patients with reduced post-surgical FT3 to eight sera from patients with FT3 levels similar to pre-surgery levels, and six healthy controls. Proteomic analysis highlights a different serum protein profile among the considered conditions. By enrichment analysis, differential proteins are involved in coagulation processes (PLMN-1.61, -1.98 in reduced vs. stable FT3, p < 0.02; A1AT fragmentation), complement system activation (CFAH + 1.83, CFAB + 1.5, C1Qb + 1.6, C1S + 7.79 in reduced vs. stable FT3, p < 0.01) and in lipoprotein particles remodeling (APOAI fragmentation; APOAIV + 2.13, p < 0.003), potentially leading to a pro-inflammatory response. This study suggests that LT4 replacement therapy might restore biochemical euthyroid conditions in thyroidectomized patients, but in some cases without re-establishing body tissue euthyroidism. Since our results, this condition is reflected by the serum protein profile.

DNMT1 and miRNAs: possible epigenetics footprints in electromagnetic fields utilization in oncology

Many studies were performed to unravel the effects of different types of Electromagnetic fields (EMFs) on biological systems. Some studies were conducted to exploit EMFs for medical purposes mainly in cancer therapy. Although many studies suggest that the EMFs exposures can be effective in pre-clinical cancer issues, the treatment outcomes of these exposures on the cancer cells, especially at the molecular level, are challenging and overwhelmingly complicated yet. This article aims to review the epigenetic mechanisms that can be altered by EMFs exposures with the main emphasis on Extremely low frequency electromagnetic field (ELF-EMF). The epigenetic mechanisms are reversible and affected by environmental factors, thus, EMFs exposures can modulate these mechanisms. According to the reports, ELF-EMF exposures affect epigenetic machinery directly or through the molecular signaling pathways. ELF-EMF in association with DNA methylation, histone modification, miRNAs, and nucleosome remodeling could affect the homeostasis of cancer cells and play a role in DNA damage repairing, apoptosis induction, prevention of metastasis, differentiation, and cell cycle regulation. In general, the result of this study shows that ELF-EMF exposure probably can be effective in cancer epigenetic therapy, but more molecular and clinical investigations are needed to clarify the safe and specific dosimetric characteristics of ELF-EMF in practice.

Differential redox proteomic profiles of serum from severe asthma patients after one month of benralizumab and mepolizumab treatment

Mepolizumab and Benralizumab are biological drugs for severe asthma patients able to reduce moderate-to-severe exacerbation rate (peripheral eosinophilial % mepolizumab 1.6 ± 1.2; benralizumab 0; p < 0.0001), improving the quality of life and lung function parameters (FEV1%: mepolizumab 87.1 ± 21.5; benralizumab 89.7 ± 15, p < 0.04). Here we report a preliminary redox proteomic study highlighting the level of oxidative burst present in serum from patients before and after one month of both treatments. Our results highlighted apolipoprotein A1 oxidation after Mepolizumab treatment, that could be related to HDL functionality and could represent a potential biomarker for the treatment. On the other hand, after one month of Benralizumab we detected higher oxidation levels of ceruloplasmin and transthyretin, considered an important oxidative stress biomarker which action help to maintain redox homeostasis.

Evaluation of the PTEN and circRNA-CDR1as Gene Expression Changes in Gastric Cancer and Normal Cell Lines Following the Exposure to Weak and Moderate 50 Hz Electromagnetic Fields

Background: Attention to the electromagnetic exposure as a targeted tumor therapy has been recently increasing. Objectives: The aim of the current study was to investigate the effect of continuous and discontinuous electromagnetic fields on cell viability as well as phosphatase and tensin homolog (PTEN) and circular (circ)-RNA CDR1as genes expression in the normal and gastric cancer (GC) cell lines. Methods: After preparing gastric cancer cell lines (AGS) and normal cells (HU02 line), they were exposed to magnetic flux densities of 0.25, 0.5, 1, and 2 mT continuously and discontinuously (1h on/1h off) for 18 hours. The 3-(4,5-dimethylthiazoyl-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to evaluate cell viability. In addition, after designing the primers, the expression of the PTEN and circ-CDR1as genes was studied using the real-time polymerase chain reaction (real-time-PCR) technique. The results were analyzed using SPSS software version 25. Results: The exposed normal and tumor cells to discontinuous electromagnetic fields resulted in increasing of cell survival rate in both normal and tumor cells. In contrast, the exposure of continuous electromagnetic field showed no effect on the viability of the normal and tumor cells at intensities of 0.25, 0.5, and 1 mT. The electromagnetic field showed a significant effect on the expression of the circ-CDR1as gene and this effect depended on the intensity of the electromagnetic field used and the cell type. We have found that the activity of PTEN gene in the normal and tumor cells increased and decreased with increasing intensity of discontinuous electromagnetic field, respectively. Conclusions: In general, the effect of electromagnetic field on gastric cancer seems to depend on the kind of exposure as well as an extent of intensity and can be used for cancer therapeutic purposes. However, more research is needed on this subject.

The Influence of the Extremely Low Frequency Electromagnetic Field on Clear Cell Renal Carcinoma

The development of new technologies and industry is conducive to the increase in the number and variety of electromagnetic field (EMF) sources in our environment. The main sources of EMF are high-voltage lines, household appliances, audio/video devices, mobile phones, radio stations, and radar devices. In the growing use of electronic devices, scientists are increasingly interested in the effects of EMF on human health. Even though many studies on the effects of EMF have already been carried out, none of them has shown a significant effect on mammals, including humans. Moreover, it is not entirely clear how EMF influences cell behavior. The International Agency for Research on Cancer on 31 May 2011, classified PEM as a possible carcinogenic factor. This study aimed to investigate the effect of the electromagnetic field on morphological and functional changes in clear cell renal carcinoma. The research was carried out on in vitro cultures of four cell lines: HEK293, 786-O 769-P, and Caki1. The results of the research showed that the EMF of low frequency had a slight effect on the viability of cells. EMF, which induced cell arrest in the G1 phase, increased the number of early apoptotic cells and decreased the number of viable cells in the 786-O line. EMF did not affect the proliferation and viability of HEK293 cells. Extreme low-frequency EMF (ELF-EMF) also showed an inhibitory effect on the migration and metastatic properties of clear cell kidney cancer cells. Moreover, shortly after the end of ELF-EMF exposure, significant increases in ROS levels were observed in all tested cell lines. As part of the work, it was shown that low-frequency EMF shows an inhibitory effect on the proliferation of primary cancer cells, diminishing their migratory, invasive, and metastatic abilities. It also increases the apoptosis of cancer cells and the amount of reactive oxygen species. Based on the results of our research, we want to point up that the effect of ELF-EMF depends on a specific metabolic state or at a specific stage in the cell cycle of the cells under study.

Role of NADPH oxidase in MAPK signaling activation by a 50 Hz magnetic field in human neuroblastoma cells

Our previous studies have shown that intermittent exposure to a 50-Hz, 100-µT sine wave magnetic field (MF) promotes human NB69 cell proliferation, mediated by activation of the epidermal growth factor receptor (EGFR) and pathways MAPK-ERK1/2 and p38; being the effects on proliferation and p38 activation blocked by the chelator N-acetylcysteine. The present work investigates the MF effects on free radical (FR) production, and the potential involvement of NADPH oxidase, the main source of reactive oxygen species (ROS), in the MF-induced activation of MAPK pathways. To this end, the field effects on MAPK-ERK1/2, -p38 and -JNK activation in the presence or absence of the NADPH oxidase inhibitor, diphenyleneiodonium chloride (DPI), as well as the expression of the p67phox subunit, were analyzed. The results revealed that field exposure increases FR production and induces early, transient expression of the cytosolic component of the NADPH oxidase, p67phox. Also, the MF-induced activation of the MAPK-JNK pathway, but not that of -ERK1/2 or -p38 pathways, was prevented in the presence of the DPI, which has been shown to significantly reduce p67phox expression. These data, together with those from previous studies, identify various, FR-dependent or -independent mechanisms, involved in the MF-induced proliferative response mediated by MAPK signaling activation.

Ceruloplasmin and oxidative stress in severe eosinophilic asthma patients treated with Mepolizumab and Benralizumab

INTRODUCTION

Severe eosinophilic asthma has been associated with Th2 airway inflammation and elevated proinflammatory cytokines and chemokines, such as IL-5. Precision therapies have recently been shown to improve asthma symptoms with a steroid-sparing effect. Two such therapies, Benralizumab and Mepolizumab, humanized IgG antibodies directed against the IL-5 receptor and IL-5, have been approved for severe eosinophilic asthma.

METHODS

Here we used a differential proteomic approach to analyse serum from patients with severe eosinophilic asthma treated with Benralizumab and Mepolizumab in a search for differential molecular modifications responsible of their effects. Enrichment analysis of differential proteins was performed for the two treatments.

RESULTS AND DISCUSSION

After one month of Benralizumab treatment we detected up-regulation of certain protein species of the antioxidant ceruloplasmin. To investigate oxidative stress, we performed redox proteomics which detected lower oxidative burst after one month of Benralizumab treatment than in the pre-treatment phase or after one month of Mepolizumab therapy.

A Review of Hydrogen Sulfide Synthesis, Metabolism, and Measurement: Is Modulation of Hydrogen Sulfide a Novel Therapeutic for Cancer?

Significance: Hydrogen sulfide (H2S) has been recognized as the third gaseous transmitter alongside nitric oxide and carbon monoxide. In the past decade, numerous studies have demonstrated an active role of H2S in the context of cancer biology. Recent Advances: The three H2S-producing enzymes, namely cystathionine γ-lyase (CSE), cystathionine β-synthase (CBS), and 3-mercaptopyruvate sulfurtransferase (3MST), have been found to be highly expressed in numerous types of cancer. Moreover, inhibition of CBS has shown anti-tumor activity, particularly in colon cancer, ovarian cancer, and breast cancer, whereas the consequence of CSE or 3MST inhibition remains largely unexplored in cancer cells. Intriguingly, H2S donation at high amounts or a long time duration has also been observed to induce cancer cell apoptosis in vitro and in vivo while sparing noncancerous fibroblast cells. Therefore, a bell-shaped model has been proposed to explain the role of H2S in cancer development. Specifically, endogenous H2S or a relatively low level of exogenous H2S may exhibit a pro-cancer effect, whereas exposure to H2S at a higher amount or for a long period may lead to cancer cell death. This indicates that inhibition of H2S biosynthesis and H2S supplementation serve as two distinct ways for cancer treatment. This paradoxical role of H2S has stimulated the enthusiasm for the development of novel CBS inhibitors, H2S donors, and H2S-releasing hybrids. Critical Issues: A clear relationship between H2S level and cancer progression remains lacking. The possibility that the altered levels of these byproducts have influenced the cell viability of cancer cells has not been excluded in previous studies when modulating H2S producing enzymes. Future Directions: The consequence of CSE or 3MST inhibition in cancer cells need to be examined in the future. Better portrayal of the crosstalk among these gaseous transmitters may not only lead to an in-depth understanding of cancer progression but also shed light on novel strategies for cancer therapy.

The effects of electromagnetic fields on cultured human retinal pigment epithelial cells

A great deal of evidence has confirmed that electromagnetic fields (EMFs) can affect the central nervous system. In this study, cultured neonatal human retinal pigment epithelial (hRPE) cells were exposed to pulsed EMF of 1 mT intensity and 50 Hz frequency 8 h daily for 3 days. In addition to cell proliferation and cell death assays, immunocytochemistry for RPE65, PAX6, nestin, and cytokeratin 8/18 proteins were performed. Real-time reverse transcriptase polymerase chain reaction (RT-PCR) was performed for NES, PAX6, RPE65, and ACTA2 gene expression. Exposed hRPE cells did not demonstrate significant change in terms of cytomorphology, cell proliferation, or cell death. Protein expression of PAX6 was decreased in treated cells compared to controls and remained unchanged for RPE65, cytokeratin 8/18, and nestin. Gene expressions of NES, RPE65, and PAX6 were decreased in treated cells as compared to controls. Gene expression of ACTA2 did not significantly change. In conclusion, viability of cultivated neonatal hRPE cells did not change after short exposure to a safe dose of pulsed EMF albeit that both gene and protein expressions of retinal progenitor cell markers were reduced. Whether longer exposure durations that are being constantly produced by widely-used electronic devices may induce significant changes in these cells, needs further investigation. Bioelectromagnetics. 39:585-594, 2018. © 2018 Wiley Periodicals, Inc.

50-Hz magnetic field impairs the expression of iron-related genes in the in vitro SOD1G93A model of amyotrophic lateral sclerosis

PURPOSE

We characterized the response to the extremely low frequency magnetic field (ELF-MF) in an in vitro model of familial Amyotrophic Lateral Sclerosis (fALS), carrying two mutant variants of the superoxide dismutase 1 (SOD1) gene.

MATERIALS AND METHODS

SH-SY5Y human neuroblastoma cells, stably over-expressing the wild type, the G93A or the H46R mutant SOD1 cDNA, were exposed to either the ELF-MF (50 Hz, 1 mT) or the sham control field, up to 72 h. Analysis of (i) viability, proliferation and apoptosis, (ii) reactive oxygen species generation, and (iii) assessment of the iron metabolism, were carried out in all clones in response to the MF exposure.

RESULTS

We report that 50-Hz MF exposure induces: (i) no change in proliferation and viability; (ii) no modulation of the intracellular superoxide and H₂O₂ levels; (iii) a significant deregulation in the expression of iron-related genes IRP1, MFRN1 and TfR1, this evidence being exclusive for the SOD1^G93A clone and associated with a slight (p = .0512) difference in the total iron content.

CONCLUSIONS

50-Hz MF affects iron homeostasis in the in vitro SOD1^G93A ALS model.

Role of Mitochondria in the Oxidative Stress Induced by Electromagnetic Fields: Focus on Reproductive Systems

Modern technologies relying on wireless communication systems have brought increasing levels of electromagnetic field (EMF) exposure. This increased research interest in the effects of these radiations on human health. There is compelling evidence that EMFs affect cell physiology by altering redox-related processes. Considering the importance of redox milieu in the biological competence of oocyte and sperm, we reviewed the existing literature regarding the effects of EMFs on reproductive systems. Given the role of mitochondria as the main source of reactive oxygen species (ROS), we focused on the hypothesis of a mitochondrial basis of EMF-induced reproductive toxicity. MEDLINE, Web of Science, and Scopus database were examined for peer-reviewed original articles by searching for the following keywords: “extremely low frequency electromagnetic fields (ELF-EMFs),” “radiofrequency (RF),” “microwaves,” “Wi-Fi,” “mobile phone,” “oxidative stress,” “mitochondria,” “fertility,” “sperm,” “testis,” “oocyte,” “ovarian follicle,” and “embryo.” These keywords were combined with other search phrases relevant to the topic. Although we reported contradictory data due to lack of uniformity in the experimental designs, a growing body of evidence suggests that EMF exposure during spermatogenesis induces increased ROS production associated with decreased ROS scavenging activity. Numerous studies revealed the detrimental effects of EMFs from mobile phones, laptops, and other electric devices on sperm quality and provide evidence for extensive electron leakage from the mitochondrial electron transport chain as the main cause of EMF damage. In female reproductive systems, the contribution of oxidative stress to EMF-induced damages and the evidence of mitochondrial origin of ROS overproduction are reported, as well. In conclusion, mitochondria seem to play an important role as source of ROS in both male and female reproductive systems under EMF exposure. Future and more standardized studies are required for a better understanding of molecular mechanisms underlying EMF potential challenge to our reproductive system in order to improve preventive strategies.

Extremely low frequency variable electromagnetic fields affect cancer and noncancerous cells in vitro differently: Preliminary study

The exposure to extremely low frequency electromagnetic field (ELF-EMF) may result in various changes at the cellular level. To identify the effect of ELF-EMF exposure on viability of cells, cancer cells (U87-MG; 143B) and noncancerous cells (BJ; HEK) in exponential growth phase were exposed or sham-exposed to different values of frequency (2, 20, 30, 50 and 60 Hz), different shapes (sinusoidal, square and triangular) and time of exposure (0.5, 1, 2, 3 h) to electromagnetic field. After exposure, viability of cells was detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). We found a different effect of exposition of cancer and noncancerous cells to ELF-EMF on viability of cells. This preliminary study revealed that electro magentic field(EMF) might serve as a potential tool for manipulating viability of cells.

Extremely Low-Frequency Magnetic Fields and Redox-Responsive Pathways Linked to Cancer Drug Resistance: Insights from Co-Exposure-Based In Vitro Studies

Electrical devices currently used in clinical practice and common household equipments generate extremely low-frequency magnetic fields (ELF-MF) that were classified by the International Agency for Research on Cancer as “possible carcinogenic.” Assuming that ELF-MF plays a role in the carcinogenic process without inducing direct genomic alterations, ELF-MF may be involved in the promotion or progression of cancers. In particular, ELF-MF-induced responses are suspected to activate redox-responsive intracellular signaling or detoxification scavenging systems. In fact, improved protection against oxidative stress and redox-active xenobiotics is thought to provide critical proliferative and survival advantage in tumors. On this basis, an ever-growing research activity worldwide is attempting to establish whether tumor cells may develop multidrug resistance through the activation of essential cytoprotective networks in the presence of ELF fields, and how this might trigger relevant changes in tumor phenotype. This review builds a framework around how the activity of redox-responsive mediators may be controlled by co-exposure to ELF-MF and reactive oxygen species-generating agents in tumor and cancer cells, in order to clarify whether and how such potential molecular targets could help to minimize or neutralize the functional interaction between ELF-MF and malignancies.

Fifty-Hertz Magnetic Field Affects the Epigenetic Modulation of the miR-34b/c in Neuronal Cells

The exposure to extremely low-frequency magnetic fields (ELF-MFs) has been associated to increased risk of neurodegenerative diseases, although the underlying molecular mechanisms are still undefined. Since epigenetic modulation has been recently encountered among the key events leading to neuronal degeneration, we here aimed at assessing if the control of gene expression mediated by miRNAs, namely miRs-34, has any roles in driving neuronal cell response to 50-Hz (1 mT) magnetic field in vitro. We demonstrate that ELF-MFs drive an early reduction of the expression level of miR-34b and miR-34c in SH-SY5Y human neuroblastoma cells, as well as in mouse primary cortical neurons, by affecting the transcription of the common pri-miR-34. This modulation is not p53 dependent, but attributable to the hyper-methylation of the CpG island mapping within the miR-34b/c promoter. Incubation with N-acetyl-l-cysteine or glutathione ethyl-ester fails to restore miR-34b/c expression, suggesting that miRs-34 are not responsive to ELF-MF-induced oxidative stress. By contrast, we show that miRs-34 control reactive oxygen species production and affect mitochondrial oxidative stress triggered by ELF-MFs, likely by modulating mitochondria-related miR-34 targets identified by in silico analysis. We finally demonstrate that ELF-MFs alter the expression of the α-synuclein, which is specifically stimulated upon ELF-MFs exposure via both direct miR-34 targeting and oxidative stress. Altogether, our data highlight the potential of the ELF-MFs to tune redox homeostasis and epigenetic control of gene expression in vitro and shed light on the possible mechanism(s) producing detrimental effects and predisposing neurons to degeneration.

Power frequency magnetic field promotes a more malignant phenotype in neuroblastoma cells via redox-related mechanisms

In accordance with the classification of the International Agency for Research on Cancer, extremely low frequency magnetic fields (ELF-MF) are suspected to promote malignant progression by providing survival advantage to cancer cells through the activation of critical cytoprotective pathways. Among these, the major antioxidative and detoxification defence systems might be targeted by ELF-MF by conferring cells significant resistance against clinically-relevant cytotoxic agents. We investigated whether the hyperproliferation that is induced in SH-SY5Y human neuroblastoma cells by a 50 Hz, 1 mT ELF magnetic field was supported by improved defence towards reactive oxygen species (ROS) and xenobiotics, as well as by reduced vulnerability against both H2O2 and anti-tumor ROS-generating drug doxorubicin. ELF-MF induced a proliferative and survival advantage by activating key redox-responsive antioxidative and detoxification cytoprotective pathways that are associated with a more aggressive behavior of neuroblastoma cells. This was coupled with the upregulation of the major sirtuins, as well as with increased signaling activity of the erythroid 2-related nuclear transcription factor 2 (NRF2). Interestingly, we also showed that the exposure to 50 Hz MF as low as 100 µT may still be able to alter behavior and responses of cancer cells to clinically-relevant drugs.

Benign Effect of Extremely Low-Frequency Electromagnetic Field on Brain Plasticity Assessed by Nitric Oxide Metabolism during Poststroke Rehabilitation

Nitric oxide (NO) is one of the most important signal molecules, involved in both physiological and pathological processes. As a neurotransmitter in the central nervous system, NO regulates cerebral blood flow, neurogenesis, and synaptic plasticity. The aim of our study was to investigate the effect of the extremely low-frequency electromagnetic field (ELF-EMF) on generation and metabolism of NO, as a neurotransmitter, in the rehabilitation of poststroke patients. Forty-eight patients were divided into two groups: ELF-EMF and non-ELF-EMF. Both groups underwent the same 4-week rehabilitation program. Additionally, the ELF-EMF group was exposed to an extremely low-frequency electromagnetic field of 40 Hz, 7 mT, for 15 min/day. Levels of 3-nitrotyrosine, nitrate/nitrite, and TNFα in plasma samples were measured, and NOS2 expression was determined in whole blood samples. Functional status was evaluated before and after a series of treatments, using the Activity Daily Living, Geriatric Depression Scale, and Mini-Mental State Examination. We observed that application of ELF-EMF significantly increased 3-nitrotyrosine and nitrate/nitrite levels, while expression of NOS2 was insignificantly decreased in both groups. The results also show that ELF-EMF treatments improved functional and mental status. We conclude that ELF-EMF therapy is capable of promoting recovery in poststroke patients.

The effects of 50 Hz magnetic field exposure on DNA damage and cellular functions in various neurogenic cells

Epidemiological studies have indicated a possible association between extremely low-frequency magnetic field (ELF-MF) exposure and the risk of nervous system diseases. However, laboratory studies have not provided consistent results for clarifying this association, despite many years of studies. In this study, we have systematically investigated the effects of 50 Hz MF exposure on DNA damage and cellular functions in both neurogenic tumor cell lines (U251, A172, SH-SY5Y) and primary cultured neurogenic cells from rats (astrocytes, microglia, cortical neurons). The results showed that exposure to a 50 Hz MF at 2.0 mT for up to 24 h did not influence γH2AX foci formation (an early marker of DNA double-strand breaks) in any of six different neurogenic cells. Exposure to a 50 Hz MF did not affect cell cycle progression, cell proliferation or cell viability in neurogenic tumor U251, A172 or SH-SY5Y cells. Furthermore, the MF exposure for 24 h did not significantly affect the secretion of cytokines (TNF-α, IL-6 or IL-1β) in astrocytes or microglia, or the phagocytic activity of microglia. In addition, MF exposure for 1 h per day did not significantly influence expression levels of microtubule-associated protein tau, microtubule-associated protein 2, postsynaptic density 95 or gephyrin in cortical neurons, indicating an absence of effects of MF exposure on the development of cortical neurons. In conclusion, our data suggest that exposure to a 50 Hz MF at 2.0 mT did not elicit DNA damage effects or abnormal cellular functions in the neurogenic cells studied.

Extremely Low-Frequency Electromagnetic Fields Affect Myogenic Processes in C2C12 Myoblasts: Role of Gap-Junction-Mediated Intercellular Communication

Extremely low-frequency electromagnetic fields (ELF-EMFs) can interact with biological systems. Although they are successfully used as therapeutic agents in physiatrics and rehabilitative practice, they might represent environmental pollutants and pose a risk to human health. Due to the lack of evidence of their mechanism of action, the effects of ELF-EMFs on differentiation processes in skeletal muscle were investigated. C2C12 myoblasts were exposed to ELF-EMFs generated by a solenoid. The effects of ELF-EMFs on cell viability and on growth and differentiation rates were studied using colorimetric and vital dye assays, cytomorphology, and molecular analysis of MyoD and myogenin expression, respectively. The establishment of functional gap junctions was investigated analyzing connexin 43 expression levels and measuring cell permeability, using microinjection/dye-transfer assays. The ELF-EMFs did not affect C2C12 myoblast viability or proliferation rate. Conversely, at ELF-EMF intensity in the mT range, the myogenic process was accelerated, through increased expression of MyoD, myogenin, and connexin 43. The increase in gap-junction function suggests promoting cell fusion and myotube differentiation. These data provide the first evidence of the mechanism through which ELF-EMFs may provide therapeutic benefits and can resolve, at least in part, some conditions of muscle dysfunction.

Evaluation of antibacterial and antibiofilm mechanisms by usnic acid against methicillin-resistant Staphylococcus aureus

AIM

To evaluate the antibacterial and antibiofilm mechanisms of usnic acid (USN) against methicillin-resistant Staphylococcus aureus from cystic fibrosis patients.

MATERIALS & METHODS

The effects exerted by USN at subinhibitory concentrations on S. aureus Sa3 strain was evaluated by proteomic, real-time PCR and electron microscopy analyses.

RESULTS & CONCLUSION

Proteomic analysis showed that USN caused damage in peptidoglycan synthesis, as confirmed by microscopy. Real-time PCR analysis showed that antibiofilm activity of USN is mainly due to impaired adhesion to the host matrix binding proteins, and decreasing lipase and thermonuclease expression. Our data show that USN exerts anti-staphylococcal effects through multitarget inhibitory effects, thus confirming the rationale for considering it 'lead compound' for the treatment of cystic fibrosis infections.

Extremely low-frequency electromagnetic fields: A possible non-invasive therapeutic tool for spinal cord injury rehabilitation

Traumatic insults to the spinal cord induce both immediate mechanical damage and subsequent tissue degeneration. The latter involves a range of events namely cellular disturbance, homeostatic imbalance, ionic and neurotransmitters derangement that ultimately result in loss of sensorimotor functions. The targets for improving function after spinal cord injury (SCI) are mainly directed toward limiting these secondary injury events. Extremely low-frequency electromagnetic field (ELF-EMF) is a possible non-invasive therapeutic intervention for SCI rehabilitation which has the potential to constrain the secondary injury-induced events. In the present review, we discuss the effects of ELF-EMF on experimental and clinical SCI as well as on biological system.

Power Frequency Magnetic Fields Affect the p38 MAPK-Mediated Regulation of NB69 Cell Proliferation Implication of Free Radicals

The proliferative response of the neuroblastoma line NB69 to a 100 µT, 50 Hz magnetic field (MF) has been shown mediated by activation of the MAPK-ERK1/2 pathway. This work investigates the MF effect on the cell cycle of NB69, the participation of p38 and c-Jun N-terminal (JNK) kinases in the field-induced proliferative response and the potential involvement of reactive oxygen species (ROS) in the activation of the MAPK-ERK1/2 and -p38 signaling pathways. NB69 cultures were exposed to the 100 µT MF, either intermittently for 24, 42 or 63 h, or continuously for periods of 15 to 120 min, in the presence or absence of p38 or JNK inhibitors: SB203580 and SP600125, respectively. Antioxidant N-acetylcysteine (NAC) was used as ROS scavenger. Field exposure induced transient activation of p38, JNK and ERK1/2. The MF proliferative effect, which was mediated by changes in the cell cycle, was blocked by the p38 inhibitor, but not by the JNK inhibitor. NAC blocked the field effects on cell proliferation and p38 activation, but not those on ERK1/2 activation. The MF-induced proliferative effects are exerted through sequential upregulation of MAPK-p38 and -ERK1/2 activation, and they are likely mediated by a ROS-dependent activation of p38.

Improved Mitochondrial and Methylglyoxal-Related Metabolisms Support Hyperproliferation Induced by 50 Hz Magnetic Field in Neuroblastoma Cells

Extremely low frequency magnetic fields (ELF-MF) are common environmental agents that are suspected to promote later stages of tumorigenesis, especially in brain-derived malignancies. Even though ELF magnetic fields have been previously linked to increased proliferation in neuroblastoma cells, no previous work has studied whether ELF-MF exposure may change key biomolecular features, such as anti-glycative defence and energy re-programming, both of which are currently considered as crucial factors involved in the phenotype and progression of many malignancies. Our study investigated whether the hyperproliferation that is induced in SH-SY5Y human neuroblastoma cells by a 50 Hz, 1 mT ELF magnetic field is supported by an improved defense towards methylglyoxal (MG), which is an endogenous cancer-static and glycating α-oxoaldehyde, and by rewiring of energy metabolism. Our findings show that not only the ELF magnetic field interfered with the biology of neuron-derived malignant cells, by de-differentiating further the cellular phenotype and by increasing the proliferative activity, but also triggered cytoprotective mechanisms through the enhancement of the defense against MG, along with a more efficient management of metabolic energy, presumably to support the rapid cell outgrowth. Intriguingly, we also revealed that the MF-induced bioeffects took place after an initial imbalance of the cellular homeostasis, which most likely created a transient unstable milieu. The biochemical pathways and molecular targets revealed in this research could be exploited for future approaches aimed at limiting or suppressing the deleterious effects of ELF magnetic fields. J. Cell. Physiol. 231: 2014-2025, 2016. © 2016 Wiley Periodicals, Inc.

Hydrogen sulfide in cancer: Friend or foe?

Hydrogen sulfide (H₂S) is the third gaseous signaling molecule that plays important roles in cancer biological processes. Recent studies indicate that H₂S has both pro-cancer and anti-cancer effects. Endogenous H₂S can exert pro-cancer functions through induction of angiogenesis regulation of mitochondrial bioenergetics, acceleration of cell cycle progression, and anti-apoptosis mechanisms. Thus, the inhibition of the production of H₂S in cancer cells may be a new cancer treatment strategy. In contrast to the pro-cancer effect of H₂S, relatively high concentrations of exogenous H₂S could suppress the growth of cancer cells by inducing uncontrolled intracellular acidification, inducing cell cycle arrest, and promoting apoptosis. Therefore, H₂S donors and H₂S-releasing hybrids could be designed and developed as novel anti-cancer drugs. In this review, the production and metabolism of H₂S in cancer cells are summarized and the role and mechanism of H₂S in cancer development and progression are further discussed.

Human Mesenchymal Stem Cells Reendothelialize Porcine Heart Valve Scaffolds: Novel Perspectives in Heart Valve Tissue Engineering

Heart valve diseases are usually treated by surgical intervention addressed for the replacement of the damaged valve with a biosynthetic or mechanical prosthesis. Although this approach guarantees a good quality of life for patients, it is not free from drawbacks (structural deterioration, nonstructural dysfunction, and reintervention). To overcome these limitations, the heart valve tissue engineering (HVTE) is developing new strategies to synthesize novel types of valve substitutes, by identifying efficient sources of both ideal scaffolds and cells. In particular, a natural matrix, able to interact with cellular components, appears to be a suitable solution. On the other hand, the well-known Wharton's jelly mesenchymal stem cells (WJ-MSCs) plasticity, regenerative abilities, and their immunomodulatory capacities make them highly promising for HVTE applications. In the present study, we investigated the possibility to use porcine valve matrix to regenerate in vitro the valve endothelium by WJ-MSCs differentiated along the endothelial lineage, paralleled with human umbilical vein endothelial cells (HUVECs), used as positive control. Here, we were able to successfully decellularize porcine heart valves, which were then recellularized with both differentiated-WJ-MSCs and HUVECs. Data demonstrated that both cell types were able to reconstitute a cellular monolayer. Cells were able to positively interact with the natural matrix and demonstrated the surface expression of typical endothelial markers. Altogether, these data suggest that the interaction between a biological scaffold and WJ-MSCs allows the regeneration of a morphologically well-structured endothelium, opening new perspectives in the field of HVTE.

Pre-exposure of neuroblastoma cell line to pulsed electromagnetic field prevents H2 O2 -induced ROS production by increasing MnSOD activity

Electromagnetic fields (EMFs) have been linked to increased risk of cancers and neurodegenerative diseases; however, EMFs can also elicit positive effects on biological systems, and redox status seems crucially involved in EMF biological effects. This study aimed to assess whether a short and repeated pulsed EMF (PEMF) could trigger adaptive responses against an oxidative insult in a neuronal cellular model. We found that a 40 min overall (four times a week, 10 min each) pre-exposure to PEMF did not affect major physiological parameters and led to a significant increase of Mn-dependent superoxide dismutase activity in the human neuroblastoma SH-SY5Y cell line. In addition, we found PEMF-pre-exposed cells exhibited decreased reactive oxygen species production following a 30 min H2 O2 challenge, with respect to non pre-exposed cells. Our findings might provide new insights on the role played by short and repeated PEMF stimulations in the enhancement of cellular defenses against oxidative insults. Although studies in normal neuronal cells would be useful to further confirm our hypothesis, we suggest that specific PEMF treatments may have potential biological repercussions in diseases where oxidative stress is implicated.

Effects of long-term 50Hz power-line frequency electromagnetic field on cell behavior in Balb/c 3T3 cells

Power-line frequency electromagnetic field (PF-EMF) was reported as a human carcinogen by some epidemiological research, but the conclusion is lack of robust experiment evidence. To identify the effects of long-term PF-EMF exposure on cell behavior, Balb/c 3T3 cells in exponential growth phase were exposed or sham-exposed to 50 Hertz (Hz) PF-EMF at 2.3 mT for 2 hours (h) one day, 5 days every week. After 11 weeks exposure, cells were collected instantly. Cell morphology was observed under invert microscope and Giemsa staining, cell viability was detected by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, cell cycle and apoptosis was examined by flow cytometry, the protein level of Proliferating Cell Nuclear Antigen (PCNA) and CyclinD1 was detected by western blot, cell transformation was examined by soft agar clone assay and plate clone forming test, and cell migration ability was observed by scratch adhesion test. It was found that after PF-EMF exposure, cell morphology, apoptosis, cell migration ability and cell transformation didn't change. However, compared with sham group, cell viability obviously decreased and cell cycle distribution also changed after 11 weeks PF-EMF exposure. Meanwhile, the protein level of PCNA and CyclinD1 significantly decreased after PF-EMF exposure. These data suggested that although long-term 50Hz PF-EMF exposure under this experimental condition had no effects on apoptosis, cell migration ability and cell transformation, it could affect cell proliferation and cell cycle by down-regulation the expression of PCNA and CyclinD1 protein.

Extremely low frequency magnetic field modulates the level of neurotransmitters

This study was aimed to observe that extremely low frequency magnetic field (ELF-MF) may be relevant to changes of major neurotransmitters in rat brain. After the exposure to ELF-MF (60 Hz, 2.0 mT) for 2 or 5 days, we measured the levels of biogenic amines and their metabolites, amino acid neurotransmitters and nitric oxide (NO) in the cortex, striatum, thalamus, cerebellum and hippocampus. The exposure of ELF-MF for 2 or 5 days produced significant differences in norepinephrine and vanillyl mandelic acid in the striatum, thalamus, cerebellum and hippocampus. Significant increases in the levels of serotonin and 5-hydroxyindoleacetic acid were also observed in the striatum, thalamus or hippocampus. ELF-MF significantly increased the concentration of dopamine in the thalamus. ELF-MF tended to increase the levels of amino acid neurotransmitters such as glutamine, glycine and γ -aminobutyric acid in the striatum and thalamus, whereas it decreased the levels in the cortex, cerebellum and hippocampus. ELF-MF significantly increased NO concentration in the striatum, thalamus and hippocampus. The present study has demonstrated that exposure to ELF-MFs may evoke the changes in the levels of biogenic amines, amino acid and NO in the brain although the extent and property vary with the brain areas. However, the mechanisms remain further to be characterized.

Cell-host, LINE and environment: Three players in search of a balance

Long interspersed nuclear elements -1 (LINEs, L1s) are retroelements occupying almost 17% of the human genome. L1 retrotransposition can cause deleterious effects on the host-cell and it is generally inhibited by suppressive mechanisms, but it can occur in some specific cells during early development as well as in some tumor cells and in the presence of several environmental factors. In a recent publication we reported that extremely low frequency pulsed magnetic field can affect L1 retrotransposition in neuroblastoma cells. In this commentary we discuss the interaction between environment and L1 activity in the light of the new emerging paradigm of host-LINE relationship.

Experimental model for ELF-EMF exposure: Concern for human health

Low frequency (LF) electromagnetic fields (EMFs) are abundantly present in modern society and in the last 20 years the interest about the possible effect of extremely low frequency (ELF) EMFs on human health has increased progressively. Epidemiological studies, designed to verify whether EMF exposure may be a potential risk factor for health, have led to controversial results. The possible association between EMFs and an increased incidence of childhood leukemia, brain tumors or neurodegenerative diseases was not fully elucidated. On the other hand, EMFs are widely used, in neurology, psychiatry, rheumatology, orthopedics and dermatology, both in diagnosis and in therapy. In vitro studies may help to evaluate the mechanism by which LF-EMFs affect biological systems. In vitro model of wound healing used keratinocytes (HaCaT), neuroblastoma cell line (SH-SY5Y) as a model for analysis of differentiation, metabolism and functions related to neurodegenerative processes, and monocytic cell line (THP-1) was used as a model for inflammation and cytokines production, while leukemic cell line (K562) was used as a model for hematopoietic differentiation. MCP-1, a chemokine that regulates the migration and infiltration of memory T cells, natural killer (NK), monocytes and epithelial cells, has been demonstrated to be induced and involved in various diseases. Since, varying the parameters of EMFs different effects may be observed, we have studied MCP-1 expression in HaCaT, SH-SY5Y, THP-1 and K562 exposed to a sinusoidal EMF at 50 Hz frequency with a flux density of 1 mT (rms). Our preliminary results showed that EMF-exposure differently modifies the expression of MCP-1 in different cell types. Thus, the MCP-1 expression needs to be better determined, with additional studies, with different parameters and times of exposure to ELF-EMF.

Wnt signaling behaves as a "master regulator" in the osteogenic and adipogenic commitment of human amniotic fluid mesenchymal stem cells

Human amniotic fluid mesenchymal stem cells (huAFMSCs) are emerging as a promising therapeutic option in regenerative medicine. Here, we characterized huAFMSC phenotype and multipotentiality. When cultured in osteogenic medium, huAFMSC displayed a significant increase in: Alkaline Phosphatase (ALP) activity and mRNA expression, Alizarin Red S staining and Runx2 mRNA expression; whereas maintaining these cells in an adipogenic culture medium gave a time-dependent increase in PPARγ and FABP4 mRNA expression, glycerol-3-phosphate dehydrogenase (GPDH) activity and positivity to Oil Red Oil staining. These results confirm that huAFMSCs can differentiate toward osteogenic and adipogenic phenotypes. The canonical Wnt/ßcatenin signaling pathway appears to trigger huAFMSC osteoblastogenesis, since during early phases of osteogenic differentiation, the expression of Dishevelled-2 (Dvl-2), of the non-phosphorylated form of ß-catenin, and the phosphorylation of glycogen synthase kinase-3ß (GSK3ß) at serine 9 were upregulated. On the contrary, during adipogenic differentiation Dvl-2 expression decreased, whereas that of ß-catenin remained unchanged. This was associated with a late increase in GSK3ß phosphorylation. Consistent with this scenario, huAFMSCs exposure to Dickkopf-1, a selective inhibitor of the Wnt signaling, abolished Runx2 and ALP mRNA upregulation during huAFMSC osteogenic differentiation, whereas it enhanced FABP4 expression in adipocyte-differentiating cells. Taken together, these results unravel novel molecular determinants of huAFMSC commitment towards osteoblastogenesis, which may represent potential targets for directing the differentiation of these cells and improving their use in regenerative medicine.

Figure

Gene expression and reproductive abilities of male Drosophila melanogaster subjected to ELF-EMF exposure

Extremely low frequency electromagnetic field (ELF-EMF) exposure is attracting increased attention as a possible disease-inducing factor. The in vivo effects of short-term and long-term ELF-EMF exposure on male Drosophila melanogaster were studied using transcriptomic analysis for preliminary screening and QRT-PCR for further verification. Transcriptomic analysis indicated that 439 genes were up-regulated and 874 genes were down-regulated following short-term exposures and that 514 genes were up-regulated and 1206 genes were down-regulated following long-term exposures (expression >2- or <0.5-fold, respectively). In addition, there are 238 up-regulated genes and 598 down-regulated genes in the intersection of short-term and long-term exposure (expression >2- or <0.5-fold). The DEGs (differentially expressed genes) in D. melanogaster following short-term exposures were involved in metabolic processes, cytoskeletal organization, mitotic spindle organization, cell death, protein modification and proteolysis. Long-term exposure let to changes in expression of genes involved in metabolic processes, response to stress, mitotic spindle organization, aging, cell death and cellular respiration. In the intersection of short-term and long-term exposure, a series of DEGs were related to apoptosis, aging, immunological stress and reproduction. To check the ELF-EMF effects on reproduction, some experiments on male reproduction ability were performed. Their results indicated that short-term ELF-EMF exposure may decrease the reproductive ability of males, but long-term exposures had no effect on reproductive ability. Down-regulation of ark gene in the exposed males suggests that the decrease in reproductive capacity may be induced by the effects of ELF-EMF exposure on spermatogenesis through the caspase pathway. QRT-PCR analysis confirmed that jra, ark and decay genes were down regulated in males exposed for 1 Generation (1G) and 72 h, which suggests that apoptosis may be inhibited in vivo. ELF-EMF exposure may have accelerated cell senescence, as suggested by the down-regulation of both cat and jra genes and the up-regulation of hsp22 gene. Up-regulation of totA and hsp22 genes during exposure suggests that exposed flies might induce an in vivo immune response to counter the adverse effects encountered during ELF-EMF exposure. Down-regulation of cat genes suggests that the partial oxidative protection system might be restrained, especially during short-term exposures. This study demonstrates the bioeffects of ELF-EMF exposure and provides evidence for understanding the in vivo mechanisms of ELF-EMF exposure on male D. melanogaster.

Global protein expression in response to extremely low frequency magnetic fields

Daily exposure to extremely low frequency magnetic fields (ELF MF) in the environment has raised public concerns on human health. Epidemiological studies suggest that exposure to ELF MF might associate with an elevated risk of cancer and other diseases in humans. To explain and/or support epidemiological observations, many laboratory studies have been conducted to elucidate the biological effects of ELF MF exposure and the underlying mechanisms of action. In order to reveal the global effects of ELF MF on protein expression, the proteomics approaches has been employed in this research field. In 2005, WHO organized a Workshop on Application of Proteomics and Transcriptomics in electromagnetic fields (EMF) Research in Helsinki, Finland to discuss the related problems and solutions. Later the journal Proteomics published a special issue devoted to the application of proteomics to EMF research. This chapter aims to summarize the current research progress and discuss the applicability of proteomics approaches in studying on ELF MF induced biological effects and the underlying mechanisms.

Retinoic acid inhibits the cytoproliferative response to weak 50‑Hz magnetic fields in neuroblastoma cells

We previously reported that intermittent exposure to a 50‑Hz magnetic field (MF) at 100 µT stimulates cell proliferation in the human neuroblastoma cell line NB69. The present study aimed to investigate whether the magnetic field-induced growth promotion also occurs at a lower magnetic flux density of 10 µT. To this purpose, NB69 cells were subjected for 42 h to intermittent exposure, 3 h on/3 h off, to a 50‑Hz MF at a 10 or 100 µT magnetic flux density. The field exposure took place either in the presence or in the absence of the antiproliferative agent retinoic acid. At the end of the treatment and/or incubation period, the cell growth was estimated by hemocytometric counting and spectrophotometric analysis of total protein and DNA contents. Potential changes in DNA synthesis were also assessed through proliferating cell nuclear antigen (PCNA) immunolabeling. The results confirmed previously reported data that a 42-h exposure to a 50‑Hz sine wave MF at 100 µT promotes cell growth in the NB69 cell line, and showed that 10 µT induces a similar proliferative response. This effect, which was significantly associated and linearly correlated with PCNA expression, was abolished by the presence of retinoic acid in the culture medium.