The Impact Of 1.8 GHz Microwaves On DNA Damage And Repair Induced By X-rays And Doxorubicin And On Protein Expression In Lymphocytes

BackgroundThe rapid increase and spread of mobile communication have raised public concern about the adverse bio-effects of microwaves from mobile phone. In terms of the genetic toxicity of microwaves, the general consensus was that nonthermal microwaves does not directly induce chromosomal or DNA damage. Recently, the research focus has been on the identification of combinative effects between nonthermal microwaves and other environmental mutagens. However, the results have been controversial and inconclusive. In our previous study, it was found that 1.8 GHz microwaves could influence the DNA repair kinesis of human peripheral lymphocytes exposed to untraviolet C, we supposed that microwaves may affect the DNA repair pathways.ObjectiveTo investigate whether 1.8 GHz microwaves exposure can impact DNA damage and repair induced by X-ray and doxorubicin in vitro, and to observe whether 1.8 GHz microwaves exposure can influence the expression of proteins related to DNA repair pathways and other functions.Methods1) After exposure to 1.8 GHz microwaves (SAR=2 W/kg,5 min on/10 min off) for 24h, the peripheral blood lymphocytes from 4 donors were immediately irradiated by X-rays (0.25,0.5,1.0 and 2.0 Gy), comet assay was performed to detect the DNA damage of the cells at 0,15,45,90,150 and 240 min after X-ray irradiation.2) The human B-cell lymphoblastoid cells (HMy2.CIR) were combinatively exposed to different doses of DOX (0,0.05,0.075,0.10,0.15 and 0.20μg/ml) and microwave(SAR= 2 W/kg,5 min on/10 min off) in five types, comet assay was performed to detect the DNA damage of the cells at 0,6,12,18 and 24 h after DOX was removed.3) Protein microarray was used to screen the protein expression levels in human B-cell lymphoblastoid cells after exposure to 1.8 GHz microwave(SAR=2 W/kg,5 min on/10 min off) for 24 h western blot assay was used to validate the results of protein microarray.Results1) The exposure of 1.8 GHz microwaves (SAR= 2 W/kg) for 2h and exposure of 1.8 GHz microwaves (SAR= 2 W/kg,5 min on/10 min off) for 24h did not induce DNA damage in human peripheral blood lymphocytes and human B-cell lymphoblastoid cells (P>0.05).2) No combinative effect was found between 1.8 GHz microwaves (SAR=2 W/kg,5 min on/10 min off,24 h) and X-rays in human lymphocytes (P＞0.05). Microwaves did not alter the DNA repair kinesis of human lymphocytes exposed to X-ray (P＞0.05).3) No combinative effect was found between 1.8 GHz microwave(SAR=2 W/kg,5 min on/10 min off,24 h) and DOX in human B-cell lymphoblastoid cells (P＞0.05). E-E-E type (exposure to RFR for 2 h, then simultaneous exposure to RFR and DOX, and exposure to RFR for 6 h,12 h,18 h and 24 h after DOX treatment) combinative exposure could obviously influence DNA repair at 6 h and 12 h after exposure to DOX for four DOX doses (0.075μg/ml,0.10μg/ml,0.15μg/ml and 0.20μg/ml) in human B-cell lymphoblastoid cells.4) As compared with microwave sham-exposure group, the expression levels of PMCA4 and RPA32 proteins were significantly down-regulated and the expression level of p73 protein was significantly up-regulated in RFR exposure group (P＜0.05) ConclusionAlthough 1.8 GHz microwaves could not directly induce DNA damage, did not influence the DNA damage induced by X-ray and DOX in lymphocytes and did not change the repair kinesis of DNA damage induced by X-ray, microwaves could influence the repair kinesis of DNA damage induced by DOX to some extent. The impact of microwaves on DNA repair may be due to the down-regulation of RPA protein, which is a key protein in nucleotide excision repair (NER) pathway.