工频磁场对人晶状体上皮细胞DNA双链断裂的影响

Effects of 50 Hz magnetic fields on DNA double-strand breaks in human lens epithelial cells

目的:采用γH2AX免疫荧光法观察工频磁场对人晶状体上皮细胞DNA双链断裂的影响。方法:将人晶状体上皮细胞暴露于0.4 mT、50 Hz工频磁场2 h、6 h、12 h、24 h、48 h,以0.1μmol/L的DNA损伤剂4-硝基喹啉-1-氧化物作用1 h作为阳性对照,结束处理后进行γH2AX免疫荧光检测。计算细胞平均焦点数。将细胞平均焦点数及焦点阳性细胞率作为评价细胞DNA双链断裂程度的指标。结果:工频磁场暴露24 h的平均焦点数、γH2AX焦点阳性细胞率分别为(2.93±0.43)、(27.88±2.59)%,与假辐照组(1.77±0.37)、(19.38±2.70)%相比,差异具有显著性(P<0.05);工频磁场暴露48 h的平均焦点数、γH2AX焦点阳性细胞率分别为(3.14±0.35)、(31.00±3.44)%,与假辐照组相比,差异具有显著性(P<0.01);而工频磁场暴露2 h分别为(2.11±0.61)、(22.44±5.09)%,6 h分别为(2.18±0.47)、(22.59±3.08)%和12 h分别为(2.35±0.43)、(23.35±2.93)%,与假辐照组比较,差异没有显著性(P>0.05)。结论:体外实验表明,0.4 mT工频磁场长时间辐照可以使人晶状体上皮细胞DNA双链断裂增加。

Objective： To investigate the effects of 50 Hz magnetic fields （MF） on DNA doublestrand breaks in human lens epithelial cells （hLECs）. Methods： The cultured human lens epithelial cells were exposed to 0.4 mT 50 Hz MF for 2 h,6 h,12 h,24 h and 48 h. Cells exposed to 4-nitroquinoline-1-oxide,a DNA damage agent,at a final concentration of 0.1 μmol/L for 1 h were used as positive controls. After exposure,cells were fixed with 4 % paraformaldehyde and for H2AX （γH2AX） immunofluorescence measurement. γH2AX foci were detected at least 200 cells for each sample. Cells were classified as positive when more than three foci per cell were observed. Mean values of loci per cell and percentage of loci positive cells were adopted as indexes of DNA double-strand breaks. Results： The mean value of loci per cell and the percentage of γH2AX loci positive cells in 50 Hz MF exposure group for 24 h were （2.93±0.43） and （27.88± 2.59）% ,respectively,which were significantly higher than those of sham-exposure group [（1.77 ±0.37） and （19.38±2.70）%,P〈0.05],and the mean value of loci per cell and the percentage of γH2AX loci positive cells in 50 Hz MF exposure group for 48 h were （3.14±0. 35） and （31.00 ±3. 44）%, which were significantly higher than those of sham-exposure group （P〈0. 01 ）. However,there was no significant difference between 50 Hz MF exposure groups for 2 h,6 h, 12 h and sham-exposure group for above two indexes （P〉0. 05）. Conclusion： 0.4 mT 50 Hz MF exposure for longer duration might induce DNA double-strand breaks in human lens epithelial cells in vitro.