Medical/biological study (experimental study)

2.45 GHz radiofrequency fields alter gene expression in cultured human cells med./bio.

By: Lee S, Johnson D, Dunbar K, Dong H, Ge X, Kim YC, Wing C, Jayathilaka N, Emmanuel N, Zhou CQ, Gerber HL, Tseng CC, Wang SM

Published in: FEBS Lett 2005; 579 (21): 4829-4836

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Aim of study (acc. to author)

To study whether radiofrequency fields can cause changes in gene expression in cultured human cells. The authors aimed to provide genome-wide coverage of the expressed genes regardless their functional categories in the radiofrequency treated cells to address if radiofrequency has biological effects.

Endpoint

molecular biosynthesis: gene expression

Exposure

- 2.45 GHz
- PW pulsed wave

Exposure	Parameters
Exposure 1: 2.45 GHz Modulation type: pulsed Exposure duration: continuous for 2 or 6 h	SAR: 10 W/kg mean SAR: 133 W/kg peak value electric field strength: 320 V/m peak value

General information

The RF exposure system has been described in detail [Gerber et al., manuscript in preparation].

Exposure 1

Main characteristics

Frequency	2.45 GHz
Type	electromagnetic field
Charakteristic	guided field
Exposure duration	continuous for 2 or 6 h

Modulation

Modulation type	pulsed
Pulse width	155 µs
Duty cycle	7.5 %

Exposure setup

Exposure source	waveguide 86.36 x 43.18 mm, pulsed magnetron
Chamber	The waveguide was filled with a 5% air-CO₂ mixture through a hole in its top surface. The bottom of the waveguide was maintained at 37 °C by temperature-controlled water circulating in direct contact with the brass surface through an exterior plastic channel glued to it.
Setup	A 25-ml culture flask containing 10 ml of cell suspension was placed inside the waveguide. The bottom of the flask was ground flat and coated with mineral oil to obtain good thermal conduction. The temperature in the bottom surface of the flask monitored by two Luxtron probes was maintained at 37.2 ± 0.2 °C.
Sham exposure	A sham exposure was conducted.
Additional info	The cells were allowed to settle down to the bottom of the flask to form a monolayer before exposure. Sham exposure was performed in an identical waveguide for 2 h only.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
SAR	10 W/kg	mean	determined by power loss	-	-
SAR	133 W/kg	peak value	calculated	-	-
electric field strength	320 V/m	peak value	calculated	-	-

Exposed system:

intact cell/cell culture
HL-60 (human acute myeloid leukaemia cells)

Methods Endpoint/measurement parameters/methodology

molecular biosynthesis: gene expression (serial analysis of gene expression (SAGE))

Investigated system:

DNA/RNA

Time of investigation:

after exposure

Main outcome of study (acc. to author)

The authors revealed that 221 genes altered their expression after a 2 h exposure. The number of affected genes increased to 759 after a 6 h exposure. Functional classification of the affected genes showed that apoptosis-related genes were among the upregulated ones and the cell cycle genes among the downregulated ones. No significant increase in the expression of heat shock protein genes was found.
These data suggest that the radiofrequency fields at 2.45 GHz can alter gene expression in cultured human cells through non-thermal mechanism.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

Air Force Office of Scientific Research/Department of Defense Multidisciplinary University Research Initiative (AFOSR/DOD MURI), USA
Department of Defense (DoD), USA

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