Medical/biological study (experimental study)

900-MHz microwave radiation enhances gamma-ray adverse effects on SHG44 cells med./bio.

By: Cao Y, Zhang W, Lu MX, Xu Q, Meng QQ, Nie JH, Tong J

Published in: J Toxicol Environ Health A 2009; 72 (11): 727-732

Aim of study (acc. to author)

To study whether pre-microwave exposure might enhance gamma radiation-induced damage in human glioma cells.

Background/further details

Cells were divided into four groups: 1) control group, 2) ionizing radiation (⁶⁰Co, 5 Gy) group, 3) microwave exposure group, and 4) "microwave + ionizing radiation" exposure group. Group 3 and 4 were further divided into different subgroups according to the intensity of microwave exposure.

Endpoint

molecular biosynthesis: oxidative stress
cell viability/cell division/proliferation: cell proliferation, cell cycle distribution, apoptosis

Exposure

- mobile communications
- mobile phone
- co-exposure

Exposure	Parameters
Exposure 1: 900 MHz Exposure duration: continuous for 2 h/day on 3 days	power density: 2 mW/cm² minimum power density: 4 mW/cm² power density: 6 mW/cm² maximum

General information

at day four after EMF exposure part of the cells were exposed to Co γ-rays at a dose of 5 Gy with a dose rate of 1Gy/min

Exposure 1

Main characteristics

Frequency	900 MHz
Type	electromagnetic field
Exposure duration	continuous for 2 h/day on 3 days

Exposure setup

Exposure source	GTEM cell

Parameters

Measurand	Value	Type	Method	Mass	Remarks
power density	2 mW/cm²	minimum	-	-	-
power density	4 mW/cm²	-	-	-	-
power density	6 mW/cm²	maximum	-	-	-

Exposed system:

intact cell/cell culture
SHG44 cells (human glioma cells)

Methods Endpoint/measurement parameters/methodology

molecular biosynthesis: oxidative stress (HSP70 expression (RT-PCR, Western blot); enzyme activity of superoxide dismutase and levels of malondialdehyde (commercial kits))
cell viability/cell division/proliferation: cell proliferation (MTT assay); cell cycle distribution and apoptosis (flow cytometry)

Investigated system:

isolated bio./chem. substance
DNA/RNA
intact cell/cell culture
cell lysates

Time of investigation:

after exposure

Main outcome of study (acc. to author)

Exposure of glioma cells to 900 MHz (group 3; 4 mW/cm² and 6 mW/cm² ) microwaves and exposure to 6 mW/cm² in combination with gamma radiation resulted in a significant inhibition of cell proliferation. Furthermore, pre-exposure with 900 MHz microwaves followed by gamma radiation significantly increased the rate of apoptosis in a dose-dependent manner.
Both, 900 MHz microwave exposure and gamma radiation did not produce significant effects on cell cycle phase distribution.
The co-exposure of electromagnetic fields and gamma radiation resulted in a synergistic effect by triggering stress response, which increased reactive oxygen species (increase of MDA, decrease of superoxide dismutase in group 4 (with 6 mW/cm²)), but the expression of HSP70 remained unchanged.
The data indicate that the adverse effects of gamma radiation on cellular functions are strengthened by electromagnetic fields.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

Jiangsu Key Laboratory of Radiation Medicine and Protection, China
Jiangsu Key Project Foundation, China

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