Research On Mitochondrial Damage And Mechanism Induced By 900MHz Microwave Radiation In Human Promyelocytic Leukemia Cells

Objective:To investigate the mitochondrial oxidative damages induced by 900MHz microwave radiation in human promyelocytic leukemia(HL-60)cells as well as the underlying mechanism.Methods:Cultured human promyelocytic leukemia cells(HL-60)were divided into the following groups:(1)unexposed control group(cells kept in the incubator),(2)sham exposure(cultured in microwave exposure system,but without microwave exposure),(3)RF exposure(irradiated with 900MHz microwave at 120μW/cm~2 power intensity,4hours/day for 5 days),(4)gamma radiation group(subjected to 6.0 Gyγ-rays),(5)Melatonin group(cells were treated with 1000 nM melatonin for 4h),(6)Sham+Mel(cells were treated with 1000nM Melatonin four hours before sham exposure),(7)RF+Mel(cells were treated with 1000nM Melatonin 4 hours prior to 900MHz microwave,4 hours/day for 5 days)and(8)GR+Mel(cells were treated with 1000nM Melatonin 4 hours prior to 6.0 Gyγ-rays irradiation).Cells were collected at different post-exposure times,viz.30minutes,4 hours and 24 hours.The levels of ROS,the contents of ATP,mtDNA copy number,the level of mtDNA transcription,the contents of 8-OHdG,the level of mt-TFA and poly-γprotein were measured.Results:The results indicated a significant increase in ROS and significant decreases in mitochondrial transcription factor A,polymerase gamma,mt DNA transcripts and mtDNA copy number in RF-exposed cells compared with those in sham-exposed control cells.In addition,there was a significant increase in 8-OHdG and a significant decrease in ATP in RF-exposed cells.The response in positive control cells exposed to gamma radiation(γ-rays,which is also known to induce ROS)was similar to those in RF-exposed cells.Conclusions:The overall data indicated that RF exposure was capable of inducing mtDNA damage mediated through ROS pathway which was associated with changing mt-TFA and poly-γprotein levels to influence mtDNA integrity and quality.Prior-treatment of RF-andγ-exposed the cells with melatonin,a well-known free radical scavenger,reversed the effects observed in RF-exposed cells.