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

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 °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 °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). Bioelectromagnetics 27:479–486, 2006. © 2006 Wiley‐Liss, Inc.