50-Hz extremely low frequency electromagnetic fields enhance cell proliferation and DNA damage: possible involvement of a redox mechanism

Abstract

HL-60 leukemia cells, Rat-1 fibroblasts and WI-38 diploid fibroblasts were exposed for 24-72 h to 0.5-1.0-mT 50-Hz extremely low frequency electromagnetic field (ELF-EMF). This treatment induced a dose-dependent increase in the proliferation rate of all cell types, namely about 30% increase of cell proliferation after 72-h exposure to 1.0 mT. This was accompanied by increased percentage of cells in the S-phase after 12- and 48-h exposure. The ability of ELF-EMF to induce DNA damage was also investigated by measuring DNA strand breaks. A dose-dependent increase in DNA damage was observed in all cell lines, with two peaks occurring at 24 and 72 h. A similar pattern of DNA damage was observed by measuring formation of 8-OHdG adducts. The effects of ELF-EMF on cell proliferation and DNA damage were prevented by pretreatment of cells with an antioxidant like alpha-tocopherol, suggesting that redox reactions were involved. Accordingly, Rat-1 fibroblasts that had been exposed to ELF-EMF for 3 or 24 h exhibited a significant increase in dichlorofluorescein-detectable reactive oxygen species, which was blunted by alpha-tocopherol pretreatment. Cells exposed to ELF-EMF and examined as early as 6 h after treatment initiation also exhibited modifications of NF kappa B-related proteins (p65-p50 and I kappa B alpha), which were suggestive of increased formation of p65-p50 or p65-p65 active forms, a process usually attributed to redox reactions. These results suggest that ELF-EMF influence proliferation and DNA damage in both normal and tumor cells through the action of free radical species. This information may be of value for appraising the pathophysiologic consequences of an exposure to ELF-EMF.

Biologic effects of SMF and paclitaxel on K562 human leukemia cells

“…Our FCM results showed that the cells treated by paclitaxel were blocked at G2/M phase (Figure 3), and this phenomenon also highlighted the especial effects of paclitaxel. Furthermore, DNA can be damaged in a variety of ways, for example, most antitumor drugs or an external source of ionizing radiation can cause DNA damage (Grassi et al 2004;Wolf et al 2005). Our results of comet assay showed that DNA damage was increased after the cells were treated with SMF and/or paclitaxel.…”

Effects of 3 Hz and 60 Hz Extremely Low Frequency Electromagnetic Fields on Anxiety-Like Behaviors, Memory Retention of Passive Avoidance and Electrophysiological Properties of Male Rats

“…Numerous investigations, from monitoring changes at molecular levels to the behavioral aspects, have been carried out in vitro and in vivo in order to illustrate different effects of ELF/EMF e.g., its impacts on cells, 1 hormones, [2][3][4][5][6] neurophysiological properties and sleep, 7,8 biochemical factors and metabolism, 9-11 pathology, 12,13 DNA damages and chromosome abnormalities, [14][15][16][17][18][19] reproduction and development, 20 and cancer. [21][22][23] On the other hand, the fact that central nervous system (CNS) as a very complicated electrochemical system may be influenced by electromagnetic fields attracts many researches interests.…”

Proteomic Analysis of Extremely Low-Frequency ElectroMagnetic Field (ELF-EMF) With Different Intensities in Rats Hippocampus

“…Furthermore, several in vitro and in vivo studies have been published on the biological effects of ELF-EMF, and a number of hypothetical mechanisms have been detected (12). A limited number of these studies have demonstrated that ELF-EMF promotes carcinogenic effects.…”