Study type: Medical/biological study (experimental study)

Mechanism of short-term ERK activation by electromagnetic fields at mobile phone frequencies. med./bio.

Published in: Biochem J 2007; 405 (3): 559-568

Aim of study (acc. to editor)

To study the effect of electromagnetic fields at mobile phone frequency on the MAPK (mitogen-activated protein kinase) cascades.

Background/further details

MAPK cascades (ERK1/2, JNK1-3, p38MAPK, BMK1) are a group of signal transduction pathways, which mediate the effects of various extracellular stimuli to regulate processes including proliferation, differentiation, metabolism and stress response.
Cells as well as isolated membranes of HeLa cells were used. Different inhibitors (reactive oxygen species inhibitor/scavenger, EGF receptor inhibitor, NADH oxidase inhibitor etc.) were used to identify mediators of irradiation-induced ERKs phosphorylation (signals are transmitted via phosphorylations of protein kinases and of regulatory proteins, for example).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 875 MHz
Exposure duration: continuous for 5, 10, (15,) 20, and 30 min
Exposure 2: 875 MHz
Exposure duration: continuous for 10 min
Exposure 3: 875 MHz
Exposure duration: continuous for 5, 10, 20, and 30 min
Exposure 4: 800–950 MHz
Exposure duration: continuous for 5, 10, 20, and 30 min
Exposure 5: 875 MHz
Exposure duration: continuous for 10 min
Exposure 6: 875 MHz
Exposure duration: continuous for 2 or 12 min
Exposure 7: 875 MHz
Exposure duration: continuous for 10 min
Exposure 8: 875 MHz
Exposure duration: continuous for 2, 5, 12, and 20 min
Exposure 9: 875 MHz
Exposure duration: continuous for 10 or 5 min
Exposure 10: 875 MHz
Exposure duration: continuous for 5, 10, and 15 min
Exposure 11: 875 MHz
Exposure duration: continuous for 15 and 30 min
Exposure 12: 875 MHz
Exposure duration: continuous for 5 and 10 min
Exposure 13: 875 MHz
Exposure duration: continuous for 10, 20, and 30 min

Exposure 1

Main characteristics
Frequency 875 MHz
Type
Exposure duration continuous for 5, 10, (15,) 20, and 30 min
Exposure setup
Exposure source
Distance between exposed object and exposure source 10 cm
Chamber The walls of the incubator with 5% CO2 humidified air at 37°C were covered with RF-absorbing material.
Setup Cells were irradiated in 6-cm dishes inside the incubator.
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power density 0.07 mW/cm² - measured - -
power density 0.23 mW/cm² - measured - -

Exposure 2

Main characteristics
Frequency 875 MHz
Type
Exposure duration continuous for 10 min
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power density 0.1 mW/cm² - measured - -
power density 0.2 mW/cm² - measured - -
power density 0.31 mW/cm² - measured - -

Exposure 3

Main characteristics
Frequency 875 MHz
Type
Exposure duration continuous for 5, 10, 20, and 30 min
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power density 0.005 mW/cm² - measured - -
power density 0.03 mW/cm² - measured - -
power density 0.11 mW/cm² - measured - -
power density 0.31 mW/cm² - measured - -

Exposure 4

Main characteristics
Frequency 800–950 MHz
Type
Exposure duration continuous for 5, 10, 20, and 30 min
Additional info 800, 875, and 950 MHz were used.
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power density 0.07 mW/cm² - measured - -

Exposure 5

Main characteristics
Frequency 875 MHz
Type
Exposure duration continuous for 10 min
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Additional info After incubation for 20 min with various inhibitors, the cells or controls were either irradiated or left untreated.
Parameters
Measurand Value Type Method Mass Remarks
power density 0.21 mW/cm² - measured - -

Exposure 6

Main characteristics
Frequency 875 MHz
Type
Exposure duration continuous for 2 or 12 min
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Additional info Some cells were left in the incubator for another 5 or 10 min after their 2-min exposure.
Parameters
Measurand Value Type Method Mass Remarks
power density 0.17 mW/cm² - measured - -

Exposure 7

Main characteristics
Frequency 875 MHz
Type
Exposure duration continuous for 10 min
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power density 0.04 mW/cm² - measured - -
power density 0.09 mW/cm² - measured - -
power density 0.17 mW/cm² - measured - -
power density 0.27 mW/cm² - measured - -

Exposure 8

Main characteristics
Frequency 875 MHz
Type
Exposure duration continuous for 2, 5, 12, and 20 min
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Additional info Some cells were left in the incubator for another 5 or 10 min after their 2-min exposure.
Parameters
Measurand Value Type Method Mass Remarks
power density 0.31 mW/cm² - measured - -

Exposure 9

Main characteristics
Frequency 875 MHz
Type
Exposure duration continuous for 10 or 5 min
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Additional info After incubation for 20 min with various inhibitors, the cells or controls were irradiated with intensities depending on the inhibitors or left untreated.
Parameters
Measurand Value Type Method Mass Remarks
power density 0.2 mW/cm² - measured - -
power density 0.21 mW/cm² - measured - 5 min
power density 0.22 mW/cm² - measured - -
power density 0.23 mW/cm² - measured - -
power density 0.24 mW/cm² - measured - -
power density 0.25 mW/cm² - measured - -

Exposure 10

Main characteristics
Frequency 875 MHz
Type
Exposure duration continuous for 5, 10, and 15 min
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power density 0.344 mW/cm² - measured - -

Exposure 11

Main characteristics
Frequency 875 MHz
Type
Exposure duration continuous for 15 and 30 min
Exposure setup
Exposure source
Setup Membranes suspended in PBS (100 µl) were irradiated in a thin tube inside the incubator.
Sham exposure A sham exposure was conducted.
Additional info After incubation for 15 min with various inhibitors, the membranes or controls were either irradiated or left untreated.
Parameters
Measurand Value Type Method Mass Remarks
power density 0.3 mW/cm² - measured - -

Exposure 12

Main characteristics
Frequency 875 MHz
Type
Exposure duration continuous for 5 and 10 min
Exposure setup
Exposure source
Setup Membranes suspended in PBS (100 µl) were irradiated in a thin tube inside the incubator.
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power density 0.24 mW/cm² - measured - -

Exposure 13

Main characteristics
Frequency 875 MHz
Type
Exposure duration continuous for 10, 20, and 30 min
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Additional info After incubation for 15 or 30 min with DPI, the membranes or cells and controls were either irradiated or left untreated.
Parameters
Measurand Value Type Method Mass Remarks
power density 0.2 mW/cm² - measured - -

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

This study delineate a detailed molecular mechanism by which electromagnetic fields at mobile phone frequency induces short-term MAPK activation and thereby transcription and other cellular processes.
The data show that ERKs, but not JNKs or p38MAPKs, are rapidly activated in response to mobile phone exposure at various frequencies and intensities. The first step is mediated in the plasma membrane by NADH oxidase, which rapidly generates reactive oxygen species. The generated reactive oxygen species then directly activate matrix metalloproteinases to release heparin-binding (Hb)-EGF, which further activate the ERK cascade.

Study character:

Study funded by

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