In Vitro Study Of DNA Damage And The Related Anti-stress Reaction Induced By Acute Exposure Of Microwave From Mobile Phone On Cultured Human Lens Epithelial Cells

Increased applications of mobile phones are of great concern to public health. These sources of non-ionizing radiation cause atmospheric pollution similar to the pollution from various industrial sources.The lens of the eye is derived from ectoderm and grows throughout life. This transparent organ consists of a single, cuboidal layer of epithelial cells on the anterior surface and elongated, terminally differentiated epithelial cells, or fiber cells, in the interior. The lens epithelial layer is critical for lens physiology, and insults to this layer can play a role in lens pathology. Many studies have found that damage to the epithelium can be an early event in cataractogenesis. However, no systematic studies have investigated the biological effects of microwave radiation from mobile phones on lens epithelial cells.It is well recognized that microwaves affect the biological functions of living organisms at both the cellular and molecular levels and can lead to the appearance of genotoxic effects. However, the mechanisms by which electromagnetic fields exert their biological effects remain poorly characterized. Special attention has been given to investigating the effects of cell phones microwave radiation on cell growth, cell cycle progression and DNA synthesis. Very low power pulsed exposure of human amnion cells at 960MHz have recently beenreported to induce a decrease in cell growth rate with increased exposure time.In our previous studies, we have demonstrated that low power microwave radiation can induce irreversible damage to rabbit lens epithelial cells (RLECs) in vivo. And found that low power microwave radiation higher than 1.00 mW/cm2 can induce lens opacity, ehe signal transduction mechanisms may related to increasing of PKC- a , c-fos and c-jun expression.The aim of this study was to determine the effect of acute microwave radiation from mobile phones on cultured hLECs (human lens epithelial cells): Whether it can induce reversibile or irreversible DNA damage to hLECs. How about realed the cell proliferate rate according to the DNA damage and repaire. And the possible anti-stress protein expression involved in.Part I : In vitro study of DNA damage and repair induced by acuteexposure of microwave from mobile phone on cultured human lens epithelial cells and related cell proliferationObjectiveTo investigate the effects of acute exposure of low-power 217Hz modulated 1.8GHz microwave radiation on the DNA of human lens epithelial cells (hLECs) and the related cell proliferation ability. MethodsCultured human lens epithelial cells were exposed to 217Hz modulated 1.8GHz microwave radiation at SAR (specific absorption rate) of 1.0, 2.0, 3.0 and 4.0w/kg for 2 hours in an sXc-1800 incubator and irradiate system, the DNA single strand breaks were detected with comet assay (single-cell gel electrophoresis) in sham-irradiated cells and irradiated cells incubated for varying periods: 0, 30, 60, 120 and 240mins after irradiation. Images of comets were digitized and analyzed using an Imagine-pro plus software, and the indexes used in this study were tail length (TL) and tail moment (TM). BrdU was added into the medium after radiation and incubated for one more hour, the cell proliferation rate was carried out using aBrdU-kit. ResultsThe difference of DNA-breaks between the exposure and sham exposure groups induced by 1.0 and 2.0w/kg irradiation were not significant in every detect time (P>0.05), as for the dose of 3.0 and 4.0w/kg there were difference in both group immediately after irradiation (P<0.01), and at the time of 0.5 hour after irradiation the difference went on at both group (P<0.01), however, the difference disappeared after one hour's incubate in 3.0w/kg group (P>0.05), and still existed in 4.0w/kg group. The cell proliferation rate had no significant difference when SAR ^ 3w/kg (P>0.05), 4.0W/kg irradiation caused cell proliferation decreased significantly (PO.01) . ConclusionIt is found no or repairable DNA damage was observed after 2 hour irradiation of 1.8 GHz microwave on human lens epithelial cells when SAR^3w/kg as measured by comet assay, and the proliferation rate of cells had no variation. 4.0W/kg irradiation caused significantly DNA damage and the breaks were un-repairable, at the same time the proliferation ability of hLECs decreased.Part IIIn vitro study of the effect of 1.8GHz electromagnetic fields of mobile phone-type on nonthermal induction of HSP70 and aB-crystallin in human lens epithelial cellsObjectiveTo study the expression of heat shock/stress protein (HSP) 70 and aB-crystallin inhuman lens epithelial cells (hLECs) induced by difference doses of microwave irradiationfrom mobile phone.MethodsCultured human lens epithelial cells (hLECs) were exposed and sham-exposed to 217Hz modulated 1.8GHz microwave radiation at four average specific absorption rates (SAR:1.0, 2.0, 3.0 and 4.0w/kg) for 2 hours in an sXc-1800 incubator and irradiate system in well controlled atmospheric conditions at 37°C and 95% air/5% CO2, HSP70 and aB-crystallin expression of LECs were measured using one-tube RT-PCR and western blot. ResultsAmongst different exposure conditions RT-PCR showed no change of HSP70 and aB-crystallin compared with sham-exposed group after 1.8GHz microwave radiation on hLECs for 2 hours. And at the level of protein, increase of HSP70 were observed when SAR=2,3,4w/kg, but no differences were found in aB-crystallin. ConclusionIt seems the increased expression of HSP70 but not aB-crystallin was possibly responsible for protect against protein degeneration of lens, persist the of hLECs proliferation and furthermore the clarity of lens.