Medical/biological study (experimental study)

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 med./bio.

By: Leszczynski D, Joenvaara S, Reivinen J, Kuokka R

Published in: Differentiation 2002; 70 (2-3): 120-129

Aim of study (acc. to author)

To determine whether non-thermal exposure of cells to 900 MHz GSM mobile phone radiation activates signal transduction pathways and induces cellular stress response in a human model.

Endpoint

activation of signal transduction pathways and induction of cellular stress response (expression status of heat shock protein 27 and p38MAPK)

Exposure

- microwaves
- mobile communications
- GSM

Exposure	Parameters
Exposure 1: 900 MHz Modulation type: pulsed Exposure duration: continuous for 1 h	SAR: 2 W/kg mean (1.8-2.5 W/kg)

Exposure 1

Main characteristics

Frequency	900 MHz
Type	electromagnetic field
Charakteristic	guided field
Exposure duration	continuous for 1 h

Modulation

Modulation type	pulsed
Pulse width	0.577 ms
Repetition frequency	217 Hz

Exposure setup

Exposure source	monopole waveguide resonator
Chamber	The irradiation chamber was placed vertically inside a cell culture incubator.
Setup	The modulated RF signal was amplified and fed to the exposure waveguide via a monopole type feed post. Two 55 mm glass Petri dishes were placed on a thin (9 mm) rectangular glass-fiber-molded temperature-controlled waterbed at the bottom of the chamber in such a way that the electric field vector was parallel to the plane of the culture medium.
Additional info	The only difference between irradiated and sham samples was that the RF-EMF radiation was either turned on or turned off.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
SAR	2 W/kg	mean	measured and calculated	-	1.8-2.5 W/kg

Measurement and calculation details

The SAR distribution in the cell culture and the E-field above the cell culture were calculated using the FDTD method. The maximum SAR was obtained in the center of the Petri dish, decreasing by about 6 dB at the edges of the dish. Simulation results were verified with measurements. The electric field in the air above the cell cultures was measured with a calibrated miniature E-field probe. The measured and the simulated E-field values differed by less than 15%. The SAR distribution was measured with small, calibrated temperature probes directly from the culture medium of increased height at room temperature outside the incubator. The measured values can be considered as the upper and lower limits of SAR, due to measurement uncertainties, and thus, they validate the simulations.

Exposed system:

intact cell/cell culture
EA.hy926 cells

Methods Endpoint/measurement parameters/methodology

molecular biosynthesis: protein phosphorylation; expression status of heat shock protein 27 and p38MAPK
activation of signal transduction pathways and induction of cellular stress response (see above)

Investigated system:

isolated bio./chem. substance

Time of investigation:

after exposure

Main outcome of study (acc. to author)

The results suggest that mobile phone radiation activates cellular signal transduction and stress response pathways. 1-hour of non-thermal exposure of the cells changes phosphorylation status of numerous, yet largely unidentified, proteins. One of these proteins was heat shock protein 27 (hsp27). Mobile phone exposure caused a transient increase in phosphorylation of hsp27. This was prevented by a specific inhibitor of p38 mitogen-activated protein kinase (p38MAPK). Mobile phone caused also transient changes in the protein expression levels of p38MAPK and hsp27.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

European Union (EU)/European Commission
Tekes (National Technology Agency), Finland

Comments on this article

Blank M et al. (2004): Comment: A biological guide for electromagnetic safety: the stress response

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