Effect of superposed electromagnetic noise on DNA damage of lens epithelial cells induced by microwave radiation.
OBJECTIVE
To investigate the influence of the 1.8-GHz radiofrequency fields (RFs) of the Global System for Mobile Communications on DNA damage, intracellular reactive oxygen species (ROS) formation, cell cycle, and apoptosis in human lens epithelial cells (hLECs) and whether the effects induced by RF could be blocked by superposing of electromagnetic noise.


METHODS
After 24-hour intermittent exposure at the specific absorption rate of 1 W/kg, 2 W/kg, 3 W/kg, and 4 W/kg, the DNA damage of hLECs was examined by alkaline comet assay and immunofluorescence microscope detection of the phosphorylated form of histone variant H2AX (gammaH2AX) foci, respectively. ROS production was quantified by the fluorescent probe 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA). Cell cycle and cell apoptosis were determined by flow cytometry.


RESULTS
DNA damage examined by alkaline comet assay was significantly increased after 3 W/kg and 4 W/kg radiation (P < 0.05), whereas the double-strand breaks (DSBs) evaluated by gammaH2AX foci were significantly increased only after 4 W/kg radiation (P < 0.05). Significantly elevated intracellular ROS levels were also detected in the 3-W/kg and 4-W/kg groups (P < 0.05). After exposure to 4 W/kg for 24 hours, hLECs exhibited significant G(0)/G(1) arrest (P < 0.05). There was no detectable difference in cell apoptosis between the microwave radiation and sham exposure groups (P > 0.05). All the effects mentioned were blocked when the RF was superposed with 2 muT electromagnetic noise.


CONCLUSIONS
Microwave radiation induced hLEC DNA damage after G(0)/G(1) arrest does not lead to cell apoptosis. The increased ROS observed may be associated with DNA damage. Superposed electromagnetic noise blocks microwave radiation-induced DNA damage, ROS formation, and cell cycle arrest.
Yao
Ke
K
Eye Center, Affiliated Second Hospital, College of Medicine, Zhejiang University, 88 Jiefang Road, Hangzhou, China.
Wu
Wei
W
Yu
Yibo
Y
Zeng
Qunli
Q
He
Jiliang
J
Lu
Deqiang
D
Wang
Kaijun
K
D017209:Apoptosis / Q000528:radiation effects; D002453:Cell Cycle / Q000528:radiation effects; D002460:Cell Line; D020552:Comet Assay; D004247:DNA / Q000528:radiation effects*; D004249:DNA Damage; D004574:Electromagnetic Fields; D004847:Epithelial Cells / Q000378:metabolism / Q000528:radiation effects*; D005434:Flow Cytometry; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D007908:Lens, Crystalline / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects*; D008856:Microscopy, Fluorescence; D008872:Microwaves; D017382:Reactive Oxygen Species / Q000378:metabolism
D017382:Reactive Oxygen Species; D004247:DNA