Medical/biological study (experimental study)

Radiofrequency radiation (900 MHz) induces Egr-1 gene expression and affects cell-cycle control in human neuroblastoma cells med./bio.

By: Buttiglione M, Roca L, Montemurno E, Vitiello F, Capozzi V, Cibelli G

Published in: J Cell Physiol 2007; 213 (3): 759-767

Aim of study (acc. to editor)

This study was conducted to determine the effects of a 900 MHz-modulated radio frequency field on viability in human neuroblastoma cells in vitro.

Background/further details

The cell viability was assessed by cell proliferation, cell cycle progression, expression studies of genes involved in cell proliferation and apoptosis (egr-1, p53, apoptosis inhibitor: bcl-2, survivin) up to chrarcterization of molecular processes via enzyme activity. The investigated transcription factor egr-1 is a gene essential for cell proliferation, cell differentiation, and apoptosis. Increased egr-1 expression and the induced Egr-1 protein is a strong transcriptional activator of key genes involved in cell death pathway.

Endpoint

cell viability/cell division/proliferation: cell viability

Exposure

- mobile communications
- GSM

Exposure	Parameters
Exposure 1: 900 MHz Modulation type: pulsed Exposure duration: continuous for 5, 15, 30 min, 6 or 24 h	electric field strength: 23 V/m effective value SAR: 1 W/kg mean

General information

Lovisolo GA, Asta D, Ciammetti L, Mancini S, Marino C, Pinto R, D'Inzeo G. 2000. In vitro exposure system operating at 900 and 1800 MHz. In: Kostarakis P, Stavroulakis P, editors. Proceeding of Millennium International Workshop on Biological Effects of Electromagnetic field. Heraklion, Crete, Greece, 17-20 October, pp 169-175.

Exposure 1

Main characteristics

Frequency	900 MHz
Type	electromagnetic field
Exposure duration	continuous for 5, 15, 30 min, 6 or 24 h

Modulation

Modulation type	pulsed
Duty cycle	12.5 %
Additional info	GSM modulated

Exposure setup

Exposure source	WPC antenna and signal generator with Proportional Integral Derivative algorithm to stabilize power
Chamber	The RF exposure system was based on a wire patch cell (WPC) antenna [Laval et al., 2000] and assembled as described in [Lovisolo et al., 2000]. Two WPCs were located in the same incubator for blinded RF and sham exposure. The absence of any interference between the two WPCs was experimentally confirmed.
Sham exposure	A sham exposure was conducted.
Additional info	Sixteen hours prior to RF exposure, cells in logarithmic growth were aliquoted from a single parental flask into individual 35-mm Petri dishes. The temperature of the dishes was maintained at 37 ± 1 °C by an appropriate cooling system [Ardoino et al., 2004]. The exposure system was turned on at least 30 min before the experiment, and the temperature in the incubator was monitored with a thermocouple probe (sensitivity ± 0.1 °C) during the exposure.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
electric field strength	23 V/m	effective value	calculated	-	-
SAR	1 W/kg	mean	calculated	-	-

Measurement and calculation details

The SAR distribution and electric field strength inside the medium were calculated using the finite integration technique (FIT) on the basis of a homogeneous model, assuming Petri dishes filled with 2 ml of culture medium [Merola et al., 2006].

Reference articles

Merola P et al. (2006): Proliferation and apoptosis in a neuroblastoma cell line exposed to 900 MHz modulated radiofrequency field
Ardoino L et al. (2004): 1800 MHz in vitro exposure device for experimental studies on the effects of mobile communication systems
Laval L et al. (2000): A new in vitro exposure device for the mobile frequency of 900 MHz

Exposed system:

intact cell/cell culture
SH-SY5Y (human neuroblastoma cell line)

Methods Endpoint/measurement parameters/methodology

molecular biosynthesis: egr-1, p53, bcl-2, survivin gene expression (RT-PCR)
cell function: enzyme activity of MAPK (subtypes ERK 1/2, SAPK/JNK, p38 MAPK: Western blot)
cell viability/cell division/proliferation: cell proliferation (see molecular biosynthesis), cell viability (MTT assay), cell cycle progression (Propidium iodide stain, flow cytometry), apoptosis (RT-PCR, Densitometry)

Investigated system:

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

Investigated organ system:

brain/CNS

Time of investigation:

before exposure
during exposure
after exposure

Main outcome of study (acc. to author)

The exposure to radiofrequency field for 24 hours exerted a significant reduction in cell viability and cell proliferation. Within exposure the egr-1- gene expression increased in 5 minutes, reaching maximum after 15 minutes, and decline to baseline levels after 6 hours. The enzyme activities of the MAPK subtypes showed similar pattern.
Cells exposed for 24 hours exhibited cell cycle progress typical for apoptosis accompanied by significant decreased gene expression of the investigated apoptosis inhibitor bcl-2 and survivin.

Study character:

medical/biological study
experimental study

Study funded by

not stated/no funding

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