Effects Of Electromagnetic Fields On DNA Double Strand Breaks In Different Cell Types From Visual System And Nervous System

With the rapid development of electric power and wireless communication technologies over the past several decades, concerns about possible adverse effects of exposure to environmental electromagnetic fields (EMF) have been raised, including extremely low frequency magnetic fields (ELF MF) from the generation, distribution and use of electricity and radiofrequency electromagnetic fields (RF EMF) related with mobile phone. Population-based epidemiological studies have indicated an association between EMF exposure and risk of cancer, or other diseases. Because DNA damages may cause errors during DNA synthesis and genetic instabilities that can result in cancer initiation and development, to investigate the effects of EMF on DNA damage becomes one of the major issues in this research field. Recently, it has been demonstrated that histone H2AX phosphorylation on a serine four residues from the carboxyl terminus (producing yH2AX) is a sensitive marker for DNA double strand breaks (DSBs). Given its specificity and sensitivity, analysis of γH2AX has become the "golden standard" for detecting DSB damage under threshold conditions of injury and widely applied in medical field. In the present study, we used yH2AX immunofluorescence assay to investigate the effects of EMF on DNA double strand breaks (DSBs) in cells.To systematically investigate the effects of EMF on DSBs, we examined the effects of1800MHz GSM (Global system for mobile communications) RF EMF or50Hz ELF EMF exposure on yH2AX foci formation in three types of cells, including Human lens epithelial cells (HLEC), microglia cells and human glioma cells (U251). The yH2AX immunofluorescence assay was applied to detect DSBs.The results showed that the average number of foci per cell, but not percentage of yH2AX foci positive cells and grading of the number of foci per cell, was significantly decreased in U251cells after exposure to RF EMF for24h when compared to sham-exposed cells (p<0.05); RF EMF exposure for0.5,1and6h did not affect the yH2AX foci formation in U251cells (p>0.05). The RF EMF exposure did not significantly change yH2AX foci formation in both microglia and HLEC cells (p>0.05). The exposure of either type of cell to50Hz MF at the intensity of2mT did not result in statistically significant changes of yH2AX foci formation (p>0.05).Therefore, the results indicate that, under the current experimental conditions, exposure to EMF does not induce DNA damage in HLEC and Microglia. Long-term exposure of RF EMF decreases yH2AX foci formation in U251cells, and the underlying mechanism and physiological significance of the decreased yH2AX foci formation await further investigations.