The reduction of menadione-induced DNA damage by radiofrequency exposure in SH-SY5Y cells is independent of exposure duration

In previous investigations we demonstrated that pre-exposure of 20 h to 1950 MHz UMTS signal was able to elicit a reduction of DNA damage induced in several mammalian cell models by chemical and physical agents in different biological assays. In the present study we aimed to address the role of RF exposure duration and timing in the observed effect. We used a well characterized waveguide-based exposure system to expose SH- SY5Y cell cultures (3h, 10h or 1 h/day for 3 days at 0.3 and 1.25 W/kg SAR followed by a treatment with menadione to analyze DNA damage in the comet assay. The protective effect was confirmed in all the conditions tested irrespective of the RF exposure duration. We also evidenced absence of effects of RF exposure alone, thus confirming that RF exposure is capable of activate a cellular process that enables the cells to better cope with a subsequent insult. To provide some hints into the possible mechanism, thioredoxin that is involved in oxidative stress, and HSF1, PARP 1 and HSP70 involved in DNA repair mechanism, were tested as possible target of RF exposure in Western Blot experiments. The preliminary results obtained under selected conditions did not evidence any alteration in the target proteins. Experiments are in progress to increase the observations at molecular level.