静磁场对人白血病细胞K562DNA的损伤模式研究

Damaging mode of human leukemia cell K562 DNA by static magnetic field

【目的】研究静磁场处理对人白血病细胞DNA的损伤模式与损伤程度,为肿瘤细胞的物理治疗提供依据。【方法】以人白血病细胞K562为试材,对其进行8.8mT静磁场处理6,12,24,30,36h后,采用MTT检测细胞活力并对细胞进行计数,同时联合使用单细胞凝胶电泳以及原子力显微镜观测方法,分析经过静磁场处理后K562细胞DNA的损伤模式。【结果】K562细胞在8.8mT静磁场中处理24h,细胞生长受到抑制,细胞彗星尾长与对照相比有显著差异(P<0.05);处理时间延长到30h,尾部DNA含量和尾长与对照相比均有极显著性差异(P<0.01),表明随着静磁场处理时间的增加,K562细胞DNA的损伤模式与损伤程度发生变化。原子力显微镜观察结果显示,静磁场处理12h,K562细胞DNA已经发生损伤,细胞DNA分子的平均高度增加,平均长度减小;静磁场处理24h,DNA链变短变粗,小片段DNA明显增多,部分DNA发生断裂;静磁场处理36h,细胞DNA形态发生显著变化,DNA大部分断裂成小片段,小片段DNA之间相互交联成板状聚集体。【结论】8.8mT静磁场对K562细胞有杀伤效应,并且这种杀伤作用具有随处理时间延长而累积的效应。随着静磁场处理时间的延长,细胞DNA经历了解链-断裂-交联和断裂并存的变化过程,DNA损伤程度亦逐步加剧。

【Objective】This study investigated the damage of human leukemic cells （K562） DNA induced by 8.8 mT static magnetic field （SMF） to improve the application of SFM to tumor physical therapy.【Method】Damaging mode of K562 cell DNA induced by exposure to SMF for 6,12,24,30,and 36 h was analyzed by the 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyl-tetrazolium bromide （MTT） assay,cell count,atomic force microscope （AFM） and single cell gel electrophoresis （SCGE）.【Result】SMF inhibited the proliferation of K562 cells.DNA damage was significantly increased after K562 cells were exposed to SMF for 24 h （P〈0.05） and the damage was extremely significantly increased after being exposed for 30 h （P〈0.01）.Damaging modes of cellular DNA induced by SMF with different exposed times were different.AFM showed that cellular DNA damage occurred after 12 h exposure with increased average height and decreased average length.After 24 h exposure,the cellular DNA became shorter and thicker,small DNA fragments increased,and some DNA fragments were broken.After 36 h exposure,DNA morphology changed significantly,most DNA broke to small fragments,and fragments cross-linked with each other.【Conclusion】The 8.8 mT SMF inhibited the proliferation of K562 cell,and the inhibition increased with the increase of exposure time.DNA of human leukemic cells experienced chain unlinking,breaking,and coexistence of crosslinking and breaks,and DNA damage increased gradually.