miRNA expression profile is altered differentially in the rat brain compared to blood after experimental exposure to 50 Hz and 1 mT electromagnetic field

Insights into the Molecular Mechanisms Regulating Cell Behavior in Response to Magnetic Materials and Magnetic Stimulation in Stem Cell (Neurogenic) Differentiation

Magnetic materials and magnetic stimulation have gained increasing attention in tissue engineering (TE), particularly for bone and nervous tissue reconstruction. Magnetism is utilized to modulate the cell response to environmental factors and lineage specifications, which involve complex mechanisms of action. Magnetic fields and nanoparticles (MNPs) may trigger focal adhesion changes, which are further translated into the reorganization of the cytoskeleton architecture and have an impact on nuclear morphology and positioning through the activation of mechanotransduction pathways. Mechanical stress induced by magnetic stimuli translates into an elongation of cytoskeleton fibers, the activation of linker in the nucleoskeleton and cytoskeleton (LINC) complex, and nuclear envelope deformation, and finally leads to the mechanical regulation of chromatin conformational changes. As such, the internalization of MNPs with further magnetic stimulation promotes the evolution of stem cells and neurogenic differentiation, triggering significant changes in global gene expression that are mediated by histone deacetylases (e.g., HDAC 5/11), and the upregulation of noncoding RNAs (e.g., miR-106b~25). Additionally, exposure to a magnetic environment had a positive influence on neurodifferentiation through the modulation of calcium channels' activity and cyclic AMP response element-binding protein (CREB) phosphorylation. This review presents an updated and integrated perspective on the molecular mechanisms that govern the cellular response to magnetic cues, with a special focus on neurogenic differentiation and the possible utility of nervous TE, as well as the limitations of using magnetism for these applications.

2.4 GHz Electromagnetic Field Influences the Response of the Circadian Oscillator in the Colorectal Cancer Cell Line DLD1 to miR-34a-Mediated Regulation

Radiofrequency electromagnetic fields (RF-EMF) exert pleiotropic effects on biological processes including circadian rhythms. miR-34a is a small non-coding RNA whose expression is modulated by RF-EMF and has the capacity to regulate clock gene expression. However, interference between RF-EMF and miR-34a-mediated regulation of the circadian oscillator has not yet been elucidated. Therefore, the present study was designed to reveal if 24 h exposure to 2.4 GHz RF-EMF influences miR-34a-induced changes in clock gene expression, migration and proliferation in colorectal cancer cell line DLD1. The effect of up- or downregulation of miR-34a on DLD1 cells was evaluated using real-time PCR, the scratch assay test and the MTS test. Administration of miR-34a decreased the expression of per2, bmal1, sirtuin1 and survivin and inhibited proliferation and migration of DLD1 cells. When miR-34a-transfected DLD1 cells were exposed to 2.4 GHz RF-EMF, an increase in cry1 mRNA expression was observed. The inhibitory effect of miR-34a on per2 and survivin was weakened and abolished, respectively. The effect of miR-34a on proliferation and migration was eliminated by RF-EMF exposure. In conclusion, RF-EMF strongly influenced regulation mediated by the tumour suppressor miR-34a on the peripheral circadian oscillator in DLD1 cells.

EVALUATION OF BCL2 AND ITS REGULATORY MIRS, MIR-15-B AND MIR-16 EXPRESSION CHANGES UNDER THE EXPOSURE OF EXTREMELY LOW-FREQUENCY ELECTROMAGNETIC FIELDS ON HUMAN GASTRIC CANCER CELL LINE

In this research, changes in the expression of B-cell lymphoma 2 (BCL2), miR-15-b and miR-16 in human adenocarcinoma gastric cancer cell line (AGS) following the exposure to magnetic flux densities (MFDs) of 0.2 and 2 mT continuously and discontinuously (1.5 h on/1.5 h off) for 18 h were investigated. Changes in the cell viability were evaluated by the MTT assay. Real-time PCR was used to evaluate the expression changes of BCL2, miR-15-b and miR-16. The results showed that extremely low frequency electromagnetic field (ELF-EMF) could significantly reduce the viability of AGS cells in the continuous MFD of 2 mT. The BCL2 expression was significantly decreased following the exposure to continuous MFDs of 0.2 and 2 mT and discontinuous MFD of 2 mT. The expressions of miR-15-b and miR-16 were significantly increased in continuous and discontinuous MFD of 2 mT. According to the results, weak and moderate extremely low-frequency electromagnetic fields can change the expressions of BCL2, miR-15-b and miR-16.

Epigenetic dysregulation in various types of cells exposed to extremely low-frequency magnetic fields

Epigenetic mechanisms regulate gene expression, without changing the DNA sequence, and establish cell-type-specific temporal and spatial expression patterns. Alterations of epigenetic marks have been observed in several pathological conditions, including cancer and neurological disorders. Emerging evidence indicates that a variety of environmental factors may cause epigenetic alterations and eventually influence disease risks. Humans are increasingly exposed to extremely low-frequency magnetic fields (ELF-MFs), which in 2002 were classified as possible carcinogens by the International Agency for Research on Cancer. This review summarizes the current knowledge of the link between the exposure to ELF-MFs and epigenetic alterations in various cell types. In spite of the limited number of publications, available evidence indicates that ELF-MF exposure can be associated with epigenetic changes, including DNA methylation, modifications of histones and microRNA expression. Further research is needed to investigate the molecular mechanisms underlying the observed phenomena.

Up-regulation of miR-144 and miR-375 in the human gastric cancer cell line following the exposure to extremely low-frequency electromagnetic fields

PURPOSE

Recently, therapeutic effects of extremely low-frequency electromagnetic field (ELF-EMF) as complementary and alternative medicine, used in the oncology field to control disease symptoms. Micro RNAs (miRs) are responsible for the post-transcriptional regulation of gene expression in the cell. This study aimed to evaluate the expression changes of miR-144 and miR-375 in the human gastric adenocarcinoma cell line (AGS) under the exposure of ELF-EMF.

MATERIALS AND METHODS

AGS cells were exposed to magnetic flux densities of 0.2 and 2 mT for 18 h, continuously and discontinuously (1.5 h on/1.5 h off). Cell viability was evaluated by MTT assay. Changes of miR-144 expression levels in AGS cells immediately after exposure and 18 and 36 h after the exposure cut-off was calculated by QRT-PCR.

RESULTS

The cell viability of AGS cells was decreased under the exposure of 0.2 and 2 mT EMFs when compared to the control. Up-regulation of miR-144 and miR-375 were observed in AGS cells under the exposure of magnetic fields.

CONCLUSIONS

The results indicated that the miR levels were significantly decreased 18 and 36 h after finishing the exposure, but not reached the normal range. The results of this investigation indicated that weak and moderate intermittent 50 Hz ELF-EMFs can induce changes in miRNA expression.

Gene biomarker discovery at different stages of Alzheimer using gene co-expression network approach

Alzheimer's disease (AD) is a chronic neurodegenerative disorder. It is the most common type of dementia that has remained as an incurable disease in the world, which destroys the brain cells irreversibly. In this study, a systems biology approach was adopted to discover novel micro-RNA and gene-based biomarkers of the diagnosis of Alzheimer's disease. The gene expression data from three AD stages (Normal, Mild Cognitive Impairment, and Alzheimer) were used to reconstruct co-expression networks. After preprocessing and normalization, Weighted Gene Co-Expression Network Analysis (WGCNA) was used on a total of 329 samples, including 145 samples of Alzheimer stage, 80 samples of Mild Cognitive Impairment (MCI) stage, and 104 samples of the Normal stage. Next, three gene-miRNA bipartite networks were reconstructed by comparing the changes in module groups. Then, the functional enrichment analyses of extracted genes of three bipartite networks and miRNAs were done, respectively. Finally, a detailed analysis of the authentic studies was performed to discuss the obtained biomarkers. The outcomes addressed proposed novel genes, including MBOAT1, ARMC7, RABL2B, HNRNPUL1, LAMTOR1, PLAGL2, CREBRF, LCOR, and MRI1and novel miRNAs comprising miR-615-3p, miR-4722-5p, miR-4768-3p, miR-1827, miR-940 and miR-30b-3p which were related to AD. These biomarkers were proposed to be related to AD for the first time and should be examined in future clinical studies.

Upregulation of miR-219a-5p Decreases Cerebral Ischemia/Reperfusion Injury In Vitro by Targeting Pde4d

BACKGROUND

Ischemic stroke is the leading cause of disability and death globally. Micro-RNAs (miRNAs) have been reported to play important roles in the development and pathogenesis of the nervous system. However, the exact function and mechanism of miRNAs have not been fully elucidated about brain damage caused by cerebral ischemia/reperfusion (I/R).

METHODS

In this study, we explored the neuroprotective effects of miR-219a-5p on brain using an in vitro ischemia model (mouse neuroblastoma N2a cells treated with oxyglucose deprivation and reperfusion), and in vivo cerebral I/R model in mice. Western blot assay and Reverse Transcription-Polymerase Chain Reaction were used to check the expression of molecules involved. Flow cytometry and cholecystokinin were used to examine cell apoptosis, respectively.

RESULTS

Our research shows that miR-219a-5p gradually decreases in cerebral I/R models in vivo and in vitro. In vitro I/R, we find that miR-219a-5p mimics provided evidently protection for cerebral I/R damage, as shown by increased cell viability and decreased the release of LDH and cell apoptosis. Mechanically, our findings indicate that miR-219a-5p binds to cAMP specific 3', 5'-cyclic phosphodiesterase 4D (PDE4D) mRNA in the 3'-UTR region, which subsequently leads to a decrease in Pde4d expression in I/R N2a cells.

CONCLUSIONS

Our results provide new ideas for the study of the mechanism of cerebral ischemia/reperfusion injury, and lay the foundation for further research on the treatment of brain I/R injury. Upregulation of miR-219a-5p decreases cerebral ischemia/reperfusion injury by targeting Pde4d in vitro.

Diagnostic Value of MiR-125b as a Potential Biomarker for Stage I Lung Adenocarcinoma

Background:

We aimed at exploring biological functions of differentially expressed miRNAs during carcinogenesis, to identify miRNAs dysegulations involved in DNA repair mechanisms, and to evaluate potential of miRNAs as prognostic and diagnostic biomarkers for early lung adenocarcinomas (LAC).

Methods:

We obtained 21 LAC and paired adjacent normal formalin-fixed, paraffinembedded lung tissues from patients who underwent curative resection for stage I LAC. We compared expression levels of eight miRNAs involved in the DNA repair mechanism between LAC and adjacent tissues.

Results:

Expressions of Hsa-miR-9-5p, hsa-miR-24-3p, hsa-miR-125a-3p, hsa-miR- 125b-5p, hsa-miR-155-5p, and hsa-let-7a-5p were significantly up-regulated in stage I LAC tissues compared with those in the adjacent tissues. In addition, expressions of hsa-mir-9-5p, hsa-mir-24-3p, hsa-mir-125a-3p, hsa-mir-125b-5p, and hsa-mir-155-5p were significantly up-regulated in stage Ia LAC tissues, whereas expressions of hsa-mir- 125a-3p and hsa-mir-125b-5p were significantly up-regulated in stage Ib LAC tissues. Receiver operating characteristic (ROC) analysis revealed that AUROC of hsa-mir-125b- 5p was 0.875 (P < 0.001).

Conclusion:

Expression of hsa-mir-125b-5p could be used to distinguish LAC from adjacent tissues. Our result suggests that hsa-mir125b-5p can be a prognostic and diagnostic biomarker for LAC.

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.