Study type: Medical/biological study (experimental study)

8-oxoG DNA Glycosylase-1 Inhibition Sensitizes Neuro-2a Cells to Oxidative DNA Base Damage Induced by 900 MHz Radiofrequency Electromagnetic Radiation. med./bio.

Published in: Cell Physiol Biochem 2015; 37 (3): 1075-1088

Aim of study (acc. to author)

The genotoxic effects of exposure of neuroblastoma cells to a 900 MHz electromagnetic field (GSM) and the role of the oxoguanine glycosylase should be investigated.

Background/further details

Oxoguanine glycosylase (also called 8-oxoG DNA glycosylase-1) is the major protective enzyme against the mutagenic effects of 8-oxoguanine (similar to 8-OHdG). 8-Oxoguanine DNA lesions result from reactive oxygen species. If the oxoguanine glycosylase plays a role in radiofrequency electromagnetic field-induced oxidative DNA damage should be investigated in the study. Therefore, the enzyme was partly disabled via transfection with siRNA ("gene silencing").
Cells were exposed to 1) SAR of 0.5 W/kg, 2) SAR of 1 W/kg, 3) SAR of 2 W/kg. For each of these groups, a separate sham exposure was conducted. Additionally, a negative control and a positive control were conducted. Groups 2 and 3 and their respective sham exposure groups were also investigated with silencing of the oxoguanine glycosylase.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 900 MHz
Modulation type: pulsed
Exposure duration: continuous for 24 hours
Exposure 2: 900 MHz
Modulation type: pulsed
Exposure duration: continuous for 24 hours
Exposure 3: 900 MHz
Modulation type: pulsed
Exposure duration: continuous for 24 hours

Exposure 1

Main characteristics
Frequency 900 MHz
Type
Exposure duration continuous for 24 hours
Modulation
Modulation type pulsed
Additional info

GSM Talk signal

Exposure setup
Exposure source
Chamber petri dishes in two rectangular chambers placed inside the same incubator with a common location for the air inlet to maintain the same environmental conditions (37°C, 5% CO2)
Setup one of the chambers was excited by an EMF signal mimicking the basic pulse structure of the GSM Talk signal at 900 MHz and the other was used for sham exposure (random choice); 8 petri dishes with cell monolayers were arranged in two towers of four dishes each; the temperature increased by 0.02°C/(W/kg) of the average SAR value during exposure; the temperature difference between exposed and sham-exposed chambers did not exceed 0.1°C
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 0.5 W/kg mean - - SAR variability < 6%

Exposure 2

Main characteristics
Frequency 900 MHz
Type
Exposure duration continuous for 24 hours
Modulation
Modulation type pulsed
Additional info

GSM Talk signal

Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 1 W/kg mean - - SAR variability < 6%

Exposure 3

Main characteristics
Frequency 900 MHz
Type
Exposure duration continuous for 24 hours
Modulation
Modulation type pulsed
Additional info

GSM Talk signal

Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 2 W/kg mean - - SAR variability < 6%

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

Without oxoguanine glycosylase silencing, only group 3 (2 W/kg) showed a significantly increased amount of DNA base damage and reactive oxygen species in exposed cells compared to sham exposed cells.
Oxoguanine glycosylase silencing caused significantly increased amounts of DNA base damage in exposed cells of groups 2 (1 W/kg) and 3 compared to exposed cells of the respective group without oxoguanine glycosylase silencing.
No effects on DNA strand breaks and on cell viability were found in any group with or without oxoguanine glycosylase silencing.
The authors conclude that exposure of neuroblastoma cells to a 900 MHz electromagnetic field (GSM) might induce oxidative DNA base damage. The oxoguanine glycosylase could play a critical role in the protection of cells against this damage.

Study character:

Study funded by

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