1800MHz射频电磁场对中国仓鼠肺成纤维细胞DNA损伤的影响

Effects of GSM 1800 MHz radiofrequency electromagnetic fields on DNA damage in Chinese hamster lung cells

目的研究全球移动通讯系统(GSM)1800MHz射频电磁场对中国仓鼠肺成纤维细胞(CHL)DNA损伤的影响。方法采用DNA双链断裂的早期标志性事件H2AX的磷酸化作为检测指标,将细胞间断(5min开,10min关)暴露于比吸收率为0或3.0W/kg的1800MHz射频电磁场1或24h后,用4%多聚甲醛固定后进行γH2AX免疫荧光分析,即用鼠源抗γH2AX单克隆抗体为一抗和异硫酸酯荧光素标记的山羊来源抗鼠抗体为二抗,显示细胞核内γH2AX的形成情况。以4,6二咪基4联苯基吲哚标记细胞核,采用ImagePro Plus图像软件分析数据,以20mg/L的DNA损伤剂二乙酰氨基芴(AAF)作用2h作为阳性对照。各处理条件至少检测50个细胞的γH2AX焦点数,焦点超过5个的细胞定义为γH2AX焦点阳性细胞,将该焦点阳性细胞率作为评价细胞DNA损伤程度的指标。结果γH2AX焦点阳性细胞率在1800MHz射频暴露24h后为(37.9±8.6)%,在阳性对照组为(50.9±9.4)%,与假辐照组的(28.0±8.4)%比较,明显增高;而射频暴露1h后的γH2AX焦点阳性细胞率为(31.8±8.7)%,增加不明显。结论1800MHz比吸收率为3.0W/kg的射频电磁场辐照24h对CHL细胞DNA有损伤作用。

Objective To study the effects of GSM 1800 MHz radiofrequency electromagnetic fields （ RF EMF） on DNA damage in Chinese hamster lung （CHL） cells. Methods The cells were intermittently exposed or sham-exposed to GSM 1800 MHz RF EMF （5 minutes on/10 minutes off） at a special absorption rate （SAR） of 3. 0 W/kg for 1 hour or 24 hours. Meanwhile, cells exposed to 2-acetaminofluorene, a DNA damage agent, at a final concentration of 20 mg/L for 2 hours were used as positive control. After exposure, cells were fixed by using 4% paraformaldehyde and processed for phosphorylated form of H2AX （γH2AX） immunofluorescence measurement. The primary antibody used for immunofluorescence was mouse monoclonal antibody against γH2AX and the secondary antibody was fluorescein isothiocyanate （FITC） -conjugated goat anti-mouse IgG. Nuclei were counterstained with 4,6-diamidino-2-phenylindole （DAPI）. The γH2AX foci and nuclei were visualized with an Olympus AX70 fluorescent microscope. Image Pro -Plus software was used to count the γH2AX foci in each cell. For each exposure condition, at least 50 cells were selected to detect γH2AX foci. Cells were classified as positive when more than five foci were detected. The percentage of γH2AX foci positive cells was adopted as the index of DNA damage. Results The percentage of γH2AX foci positive cell of 1800 MHz RF EMF exposure for 24 hours （37.9 ± 8. 6）% or 2-acetylaminofluorene exposure （50. 9 ± 9.4 ） % was significantly higher compared with the sham-exposure （ 28. 0 ± 8.4 ） %. However, there was no significant difference between the sham-exposure and RF EMF exposure for 1 hour （31.8 ± 8. 7）%. Conclusion 1800 MHz RF EMF （SAR, 3. 0 W/kg） for 24 hours might induce DNA damage in CHL cells.