title: Non-thermal activation of the hsp27/p38MAPK stress pathway by mobile phone radiation in human endothelial cells: molecular mechanism for cancer- and blood-brain barrier-related effects.
abstract: We have examined whether non-thermal exposures of cultures of the human endothelial cell line EA.hy926 to 900 MHz GSM mobile phone microwave radiation could activate stress response. Results obtained demonstrate that 1-hour non-thermal exposure of EA.hy926 cells changes the phosphorylation status of numerous, yet largely unidentified, proteins. One of the affected proteins was identified as heat shock protein-27 (hsp27). Mobile phone exposure caused a transient increase in phosphorylation of hsp27, an effect which was prevented by SB203580, a specific inhibitor of p38 mitogen-activated protein kinase (p38MAPK). Also, mobile phone exposure caused transient changes in the protein expression levels of hsp27 and p38MAPK. All these changes were non-thermal effects because, as determined using temperature probes, irradiation did not alter the temperature of cell cultures, which remained throughout the irradiation period at 37 +/- 0.3 degrees C. Changes in the overall pattern of protein phosphorylation suggest that mobile phone radiation activates a variety of cellular signal transduction pathways, among them the hsp27/p38MAPK stress response pathway. Based on the known functions of hsp27, we put forward the hypothesis that mobile phone radiation-induced activation of hsp27 may (i) facilitate the development of brain cancer by inhibiting the cytochrome c/caspase-3 apoptotic pathway and (ii) cause an increase in blood-brain barrier permeability through stabilization of endothelial cell stress fibers. We postulate that these events, when occurring repeatedly over a long period of time, might become a health hazard because of the possible accumulation of brain tissue damage. Furthermore, our hypothesis suggests that other brain damaging factors may co-participate in mobile phone radiation-induced effects.
authors.affiliation: Bio-NIR Research Group, Radiobiology Laboratory, Department of Research and Environmental Surveillance, STUK - Radiation and Nuclear Safety Authority, Laippatie 4, FIN-00880, Helsinki, Finland. dariusz.leszczynski@stuk.fi
authors.forename: Dariusz
authors.initials: D
authors.lastname: Leszczynski
authors.forename: Sakari
authors.initials: S
authors.lastname: Joenväärä
authors.forename: Jukka
authors.initials: J
authors.lastname: Reivinen
authors.forename: Reetta
authors.initials: R
authors.lastname: Kuokka
mesh_terms: D002460:Cell Line; D040421:Cell Phone; D004727:Endothelium / Q000166:cytology / Q000528:radiation effects*; D004789:Enzyme Activation; D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D006801:Humans; D007150:Immunohistochemistry; D020935:MAP Kinase Signaling System / Q000502:physiology*; D008872:Microwaves / Q000009:adverse effects*; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology / Q000528:radiation effects*; D008954:Models, Biological; D018832:Molecular Chaperones; D009363:Neoplasm Proteins / Q000378:metabolism*; D010766:Phosphorylation; D013997:Time Factors; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D055551:HSP27 Heat-Shock Proteins; C057725:HSPB1 protein, human; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D009363:Neoplasm Proteins; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases