Effects Of 2450MHz Microwave Radiation On Proliferation Activity Of Nasopharyngeal Carcinoma Cell And Its Mechanism

Microwave in the frequency range of 300MHz～300GHz, has long been used in radar, space research, telecommunication, industrial processing and medicine. In recent years, a large increase in the number of people who are potentially exposed to microwave radiation occurred with the introduction of household microwave ovens (2450 MHz) and mobile communications devices (800～1800 MHz). Public attention has been drawn to the possible biological effects and health hazards from exposure to microwave radiation.The biological effects of microwave are divided into two types: thermal and non-thermal effects. Thermal effects are associated with heat generated during microwave radiation when the specific absorption rate (SAR) is higher. Lower intensity exposures that do not invoke thermoregulation are referred to as non-thermal effect that was less reported. Thermal and non-thermal induced bio-effects are correlated with some parameters of microwave such as frequencies, power densities, and pulsed modulations. About the genotoxic effects of 2450 MHz microwave radiation, the majority data were not reported. The reported data showed the incidence of dicentric chromosomes, acentric fragments and micronuclei, DNA fragment rearrangement and gene expression alteration to be increased.RESEARCH CONTENTS AND RESULTS:1. The effects of microwave radiation on proliferation activity and cell cycle of nasopharyngeal carcinoma cell. The expriement were divided into four groups, control, 10, 20 and 30 mW/cm~2 group. The methods of MTT and flow cytometry ( FCM )were used to detect the effects of microwave radiation on proliferation activity of nasopharyngeal carcinoma cell and its cell cyclye. Our results suggested that with increasing of microwave radiation, MTT assay showed the reduced rate of cell activity. There were significally different in the rates of cell activity at 20 and 30 mW/cm~2 group than those of in 10 mW/cm~2 group and control group. FCM showed that obvious subdiploid peaks were found in 20 and 30 mW/cm2 group, which was significantly different in comparison with 10 mW/cm~2 group.2. Effect of microwave radiation on the morphologic changes of nasopharyngeal carcinoma cell. The methods of electron microscopy and TUNEL were used to detect the effects of microwave radiation treatment on morphologic changes and apoptosis of nasopharyngeal carcinoma cell. The cells were observed light swelling and brim illegibility in 10mW/cm~2 group. The numble of the doffing,, suspended and chippy cells were increased in 20 and 30 mW/cm~2 group. With increasing of microwave radiation, parts of endocytoplasmic reticulum were expanded and many of vacuolar degeneration of cyctoplasm were seen in carcinoma cells in 10mW/cm~2 group, as well as those were seen in 20 and 30 mW/cm~2 groups. A great number of apoptotic cells could be found in 30 mW/cm~2 group. The positive cells of Tunel were significatly different among 10mW/cm~2 and 20, 30 mW/cm~2 group (P<0.05) . When cells were going to apoptosis, usually DNA single-strand breakage and double-strand breakages took place. According to this principle, we observed DNA single and double-strand breakages in nasopharyngeal carcinoma cell, by the klenow fragment of DNA polymerase I -mediated nick end labeling method (KLENOW method), and terminal deoxynucleotidy I transferas-mediated dUTP nick end labeling (TUNEL method) . The results showed that the damages of DNA single and double-strand breaks in nasopharyngeal carcinoma cell were significantly increased.3. Effect of Microwave Radiation on the levels of MDA and activity of SOD in nasopharyngeal carcinoma cells. The methods of TAB and NBT were used to detect the effect of microwave radiation on the levels of MDA and activity of SOD in nasopharyngeal carcinoma cells. With increasing of microwave radiation , TAB assay showed that the levels of MAD were increased 1.4 and 3.5 times in 20 and 30 mW/cm~2 groups compared with control group, which were obviously different compared with control group (P < 0.05) . NBT assay showed that the activity of SOD were reduced to 68.2%,46.2% and 36.0 % in three groups respectively, which were statistical significance in comparison with control group (P<0.01) .CONCLUSION:1. Microwave radiation could inhibite cell proliferation and block cell cycle of carcinoma cell.2. Microwave radiation can affect nasopharyngeal carcinoma cell morphologic and promote cell apoptosis.3. Microwave Radiation can promote the levels of MAD and reduced SOD activity.