Effects of a 2450 MHz high-frequency electromagnetic field with a wide range of SARs on the induction of heat-shock proteins in A172 cells

Abstract

In this study, we investigated whether exposure to 2450 MHz high-frequency electromagnetic fields (HFEMFs) could act as an environmental insult to evoke a stress response in A172 cells, using HSP70 and HSP27 as stress markers. The cells were exposed to a 2450 MHz HFEMF with a wide range of specific absorption rates (SARs: 5-200 W/kg) or sham conditions. Because exposure to 2450 MHz HFEMF at 50-200 W/kg SAR causes temperature increases in culture medium, appropriate heat control groups (38-44 degrees C) were also included. The expression of HSP 70 and HSP 27, as well as the level of phosphorylated HSP 27 ((78)Ser) (p-HSP27), was determined by Western blotting. Our results showed that the expression of HSP 70 increased in a time and dose-dependent manner at >50 W/kg SAR for 1-3 h. A similar effect was also observed in corresponding heat controls. There was no significant change in HSP 27 expression caused by HFEMF at 5-200 W/kg or by comparable heating for 1-3 h. However, HSP 27 phosphorylation increased transiently at 100 and 200 W/kg to a greater extent than at 40-44 degrees C. Phosphorylation of HSP 27 reached a maximum after 1 h exposure at 100 W/kg HFEMF. Our results suggest that exposure to a 2450 MHz HFEMF has little or no apparent effect on HSP70 and HSP27 expression, but it may induce a transient increase in HSP27 Phosphorylation in A172 cells at very high SAR (>100 W/kg).

EXPOSURE TO 2.45 GHz MICROWAVE RADIATION PROVOKES CEREBRAL CHANGES IN INDUCTION OF HSP-90 α/β HEAT SHOCK PROTEIN IN RAT.

“…Although various authors have associated changes in levels of expression of heat-shock proteins with exposure to non ionizing radiation [3,9,37], other authors of in vitro studies with embryos [38] and of in vivo studies attribute such changes to thermal stimuli. To our knowledge no in vivo studies have described changes in the levels and distribution of the heat shock protein HSP-90 in several rat brain regions analyzed after acute controlled exposure of the animals to 2.45 GHz at non thermal SAR in a GTEM cell (see Tables 2, 3).…”

“…As a consequence there has been increased interest in studies of electromagnetic contamination at this frequency and of related thermal [3,4] and non thermal effects [5,6] in biological systems.…”

Classification of Biological Effect of 1,763 MHz Radiofrequency Radiation Based on Gene Expression Profiles

“…In contrast, if we apply higher SAR (＞ 10 W/kg) and/or prolonged RF exposure, the temperature of exposure system is increased even in the presence of cooling system. In this sense, the expression of HSP70 increased time-and dose-dependently at above 50 W/kg SAR of 2,450 MHz for 1∼3 h in glioblastoma cells (Wang et al, 2006). However, the expression of heat shock proteins may change upon non-specific stimuli.…”

Expression of Heat Shock Proteins in Human Fibroblast Cells under Magnetic Resonant Coupling Wireless Power Transfer

“…Expressed in response to cellular stress conditions such as heat, heat shock proteins (Hsps) help other proteins assemble correctly and prevent unfolding, and modulate a wide range of cellular functions, such as thermotolerance, anti-apoptosis function and immunogenicity. Many in vitro studies of the relationship between expression of Hsps and various frequency ranges of EMFs, such as extremely low frequency, intermediate frequency and radio frequency fields, have been conducted [18][19][20][21]. To our knowledge, however, there have been very few in vitro studies evaluating the expression of Hsps not only for resonant coupling WPT but also for EMFs near the 10-MHz frequency range.…”