射频电磁场诱导细胞DNA损伤振荡效应的作用机制研究

Although the genotoxicity of radio-frequency electromagnetic fields (RF-EMF) was widely studied, the debate continuous due to the inconsistent and even incomparable results from different studies. The key point is that the mechanism of RF-EMF acting on organism is not clear. Our recent experiments showed that exposure to RF-EMF can induce DNA damage oscillation in wild-type mouse embryonic fibroblasts (MEFs), and total ROS scavenger (e.g., NAC) can block the effect, suggesting ROS might playing an important role in RF-EMF induced DNA damage oscillation. On the other hand, accumulating evidences show that exogenous stimuli (e.g., chemicals) induce ROS oscillation through calcium flux and affect cellular functions. Thus, we propose that RF-EMF exposure induces DNA damage oscillation through oscillation of mitochondrial ROS by regulation of calcium flux. To test our hypothesis, this study will 1) evaluate the effect of RF-EMF exposure on ROS to determine whether RF-EMF induce ROS oscillation; 2) determine whether mitochondrial ROS plays an important role in RF-EMF induced DNA damage oscillation; 3) to investigate the mechanism how RF-EMF induce ROS oscillation. We expect to determine the role of mitochondrial ROS in RF-EMF induced DNA damage oscillation in MEF cells, and provide a novel biophysical mechanism on RF-EMF acting on mitochondrial ROS. Our study will provide evidence of RF-EMF induced DNA damage which may improve our understandings on the mechanism of RF-EMF acting on organism, and provide scientific mechanism explanation on epidemiological findings e.g., health effects induced by RF-EMF exposure.

射频电磁场（如手机辐射）与肿瘤的关系至今没有定论，且缺乏实验室研究的一致性证据，其关键在于低强度射频电磁场生物作用机制不清楚。围绕射频电磁场的遗传毒性，我们开展了系列研究，发现射频电磁场暴露能诱导细胞内DNA损伤振荡效应，且细胞总ROS清除剂能阻断该效应。已有研究显示，外源性理化因素通过钙离子流变化引起ROS振荡，进而影响细胞功能。因此，我们提出，射频电磁场可能通过诱导ROS振荡引起DNA损伤振荡。为证实这一科学假设，本项目拟研究1）射频电磁场是否诱导细胞内和线粒体ROS发生振荡效应；2）线粒体ROS在射频电磁场致DNA损伤振荡效应中的作用；3）射频电磁场引起ROS振荡的生物物理机制。项目预期明确射频电磁场是否通过作用线粒体引起ROS振荡进而诱导DNA损伤振荡，并提出生物物理作用机制；研究成果为阐明射频电磁场生物学效应作用机制的提供实验基础，为电磁辐射与人群健康效应研究结果提供科学解释。

本研究是基于射频电磁场能够诱导细胞DNA损伤振荡这一发现而开展的进一步研究，主要研究了1）射频电磁场是否诱导细胞内ROS振荡；2）ROS在射频电磁场诱导DNA损伤振荡中的作用；３）射频电磁场引起ROS振荡的生物物理机制。通过研究我们发现射频电磁场能够诱导细胞内ROS产生振荡，并且ROS清除剂能够明显改变射频电磁场诱导的DNA损伤振荡，但并未完全消除振荡，说明ROS振荡在射频电磁场诱导DNA损伤振荡过程中起着一定的作用，同时应该还存在其他未知的作用机制。在对射频电磁场诱导细胞ROS振荡机制的研究上，我们检测了细胞内钙离子浓度、线粒体膜电势，发现射频电磁场能够诱导线粒体内钙离子浓度和膜电势发生明显振荡，提示线粒体可能在该过程中起重要作用。随后，我们通过线粒体内膜钙离子泵（MCU）特异性抑制剂Ru360和线粒体呼吸链解偶联剂FCCP处理细胞，发现Ru360能够显著增强射频电磁场对细胞的DNA损伤效应，并通过蛋白组学以及后续实验证实了Ru360是通过抑制线粒体ATP合成进而导致细胞对射频电磁场敏感。这是本项目研究过程中的重要发现，为接下来我们在细胞应答射频电磁场机制方面研究打下了良好的基础的同时也开辟了新的研究方向。