Medical/biological study (experimental study)

HSP70 expression in human trophoblast cells exposed to different 1.8 Ghz mobile phone signals med./bio.

By: Franzellitti S, Valbonesi P, Contin A, Biondi C, Fabbri E

Published in: Radiat Res 2008; 170 (4): 488-497

Aim of study (acc. to author)

To study HSP70 gene expression and protein expression in human trophoblast cells after exposure to 1.8 GHz (continuous wave and different GSM signals) to assess the possible effects of time and modulation schemes on cell responses.

Background/further details

Experiments for each modulation scheme were carried out with three different exposure periods (4, 16 and 24 hours). For each condition, six independent experiments were performed for gene expression and protein expression. Positive controls were performed with 43 °C heat (1 h) and negative controls were performed in the incubator.

Endpoint

molecular biosynthesis: protein expression and gene expression of HSP

Exposure

- TDMA
- mobile communications
- digital mobile phone
- GSM

Exposure	Parameters
Exposure 1: 1.8 GHz Modulation type: CW Exposure duration: intermittent, 5 min on/10 min off, for 4, 16, and 24 h	SAR: 2 W/kg average over time
Exposure 2: 1.8 GHz Modulation type: pulsed Exposure duration: intermittent, 5 min on/10 min off, for 4, 16, and 24 h	SAR: 2 W/kg average over time SAR: 16 W/kg peak value
Exposure 3: 1.8 GHz Modulation type: pulsed Exposure duration: intermittent, 5 min on/10 min off, for 4, 16, and 24 h	SAR: 2 W/kg average over time SAR: 22.77 W/kg peak value

Exposure 1

Main characteristics

Frequency	1.8 GHz
Type	electromagnetic field
Charakteristic	guided field
Exposure duration	intermittent, 5 min on/10 min off, for 4, 16, and 24 h

Modulation

Modulation type	CW

Exposure setup

Exposure source	cavity resonator waveguide
Chamber	The exposure system was developed and built following the specifications in [Schonborn et al., 2000]. Two 128.5 x 65 x 424 mm³ brass single-mode waveguide resonators equipped with ventilators and air temperature probes were placed inside one of the two incubators.
Setup	Six 35-mm Petri dishes per resonator, each containing 3 ml of medium, were arranged in two stacks using a plastic holder and were placed in the H-field maximum of the standing wave (E-polarization).
Sham exposure	A sham exposure was conducted.
Additional info	Within each experiment, six dishes each were RF and sham exposed. Signal characteristics and the exposure/sham condition were assigned to the two waveguides by a computer-controlled signal unit ensuring blinded conditions.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
SAR	2 W/kg	average over time	measured and calculated	-	-

Additional parameter details

The absolute uncertainty on SAR was 20%, and the variation due to the non-uniformity of the field distribution was 29%. The temperature of the monolayer cells was uniformly distributed without localized hot spots. The increase in temperature due to the RF field was well below 0.1°C per unit SAR with a thermal time constant of 280 s. The temperature differences between RF and sham exposed cells were below 0.1°C.

Measurement and calculation details

The system was characterized numerically by FDTD simulation, and results were verified extensively using a near-field scanner DASY3 equipped with dosimetric field and temperature probes [Schuderer et al., 2004]. Direct temperature measurements were performed in preliminary experiments using a temperature probe inserted in the medium which confirmed the results of the simulation.

Exposure 2

Main characteristics

Frequency	1.8 GHz
Type	electromagnetic field
Charakteristic	guided field
Exposure duration	intermittent, 5 min on/10 min off, for 4, 16, and 24 h

Modulation

Modulation type	pulsed
Duty cycle	12.5 %
Repetition frequency	217 Hz
Pulse type	rectangular
Additional info	GSM-217 Hz signal (speaking only) with every 26th frame being idle, adding an 8 Hz modulation component [Pedersen, 1997]

Exposure setup

Exposure source	same setup as exposure 1
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
SAR	2 W/kg	average over time	measured and calculated	-	-
SAR	16 W/kg	peak value	measured and calculated	-	-

Exposure 3

Main characteristics

Frequency	1.8 GHz
Type	electromagnetic field
Charakteristic	guided field
Exposure duration	intermittent, 5 min on/10 min off, for 4, 16, and 24 h

Modulation

Modulation type	pulsed
Duty cycle	12.5 %
Repetition frequency	217 Hz
Pulse type	rectangular
Additional info	GSM-Talk signal (33% speaking and 67% hearing) with temporal changes between GSM-217 Hz and GSM-DTX (transmission reduced to 12 active frames per 104 frames) resulting in 2, 8, and 217 Hz modulation components

Exposure setup

Exposure source	same setup as exposure 1
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
SAR	2 W/kg	average over time	measured and calculated	-	-
SAR	22.77 W/kg	peak value	measured and calculated	-	-

Reference articles

Schuderer J et al. (2004): High Peak SAR Exposure Unit With Tight Exposure and Environmental Control for In Vitro Experiments at 1800 MHz
Schönborn F et al. (2000): Design, optimization, realization, and analysis of an in vitro system for the exposure of embryonic stem cells at 1.71 GHz
Pedersen GF (1997): Amplitude modulated RF fields stemming from a GSM/DCS-1800 phone

Exposed system:

intact cell/cell culture
HTR-8/SVneo (human trophoblast cell line)

Methods Endpoint/measurement parameters/methodology

molecular biosynthesis: protein expression (HSP70, HSC70: Western blot) and gene expression (HSP70-A, HSP70-B, HSP70-C, HSC70; semi-quantitative RT-PCR)
cell viability/cell division/proliferation: cell viability (MTT assay)

Investigated system:

isolated bio./chem. substance
DNA/RNA
protein

Time of investigation:

after exposure

Main outcome of study (acc. to author)

There were no significant differences in cell viability between all groups. No significant differences in either HSC70 or HSP70 protein expression were observed between radiofrequency electromagnetic field exposed and sham exposed samples. After exposure to heat shock the trophoblast cells showed a significant overexpression of the HSP70 protein, while HSC70 was unaffected. The HSP70-A, HSP70-B and HSC70 transcripts did not change in cells exposed to radiofrequency electromagnetic fields. Levels of the HSP70-C transcript were significantly enhanced after 24 hours exposure to GSM-217 Hz and reduced after 4 hours and 16 hours exposure to GSM-talk signals.
The results suggest that the expression analysis for multiple transcripts, though encoding the same or similar protein products, can identify subtle changes that would not be detected at the protein level.

Study character:

medical/biological study
experimental study
full/main study
blind study

Study funded by

Ministero dell'Istruzione, dell'Università e della Ricerca (MIUR (formerly MURST (Ministero dell' Università e della Ricerca Scientifica e Tecnologica); Ministry of Education, University and Research), Italy

Valbonesi P et al. (2014): Effects of the exposure to intermittent 1.8 GHz radio frequency electromagnetic fields on HSP70 expression and MAPK signaling pathways in PC12 cells
Cervellati F et al. (2013): 17-Estradiol Counteracts the Effects of High Frequency Electromagnetic Fields on Trophoblastic Connexins and Integrins
Calabro E et al. (2012): Modulation of heat shock protein response in SH-SY5Y by mobile phone microwaves
Ding GR et al. (2009): Comparison of Hsps expression after radio-frequency field exposure in three human glioma cell lines
Cervellati F et al. (2009): Effect of high-frequency electromagnetic fields on trophoblastic connexins
Valbonesi P et al. (2008): Evaluation of HSP70 expression and DNA damage in cells of a human trophoblast cell line exposed to 1.8 GHz amplitude-modulated radiofrequency fields
Yu Y et al. (2008): Effects of exposure to 1.8 GHz radiofrequency field on the expression of Hsps and phosphorylation of MAPKs in human lens epithelial cells
Huang TQ et al. (2008): Characterization of biological effect of 1763 MHz radiofrequency exposure on auditory hair cells
Buttiglione M et al. (2007): Radiofrequency radiation (900 MHz) induces Egr-1 gene expression and affects cell-cycle control in human neuroblastoma cells
Sanchez S et al. (2007): In Vitro Study of the Stress Response of Human Skin Cells to GSM-1800 Mobile Phone Signals Compared to UVB Radiation and Heat Shock
Lixia S et al. (2006): Effects of 1.8 GHz radiofrequency field on DNA damage and expression of heat shock protein 70 in human lens epithelial cells
Nylund R et al. (2006): Mobile phone radiation causes changes in gene and protein expression in human endothelial cell lines and the response seems to be genome- and proteome-dependent
Qutob SS et al. (2006): Microarray gene expression profiling of a human glioblastoma cell line exposed in vitro to a 1.9 GHz pulse-modulated radiofrequency field
Chauhan V et al. (2006): Gene Expression Analysis of a Human Lymphoblastoma Cell Line Exposed In Vitro to an Intermittent 1.9 GHz Pulse-Modulated Radiofrequency Field
Lantow M et al. (2006): Free radical release and HSP70 expression in two human immune-relevant cell lines after exposure to 1800 MHz radiofrequency radiation
Lee S et al. (2005): 2.45 GHz radiofrequency fields alter gene expression in cultured human cells
Capri M et al. (2004): 1800 MHz radiofrequency (mobile phones, different Global System for Mobile communication modulations) does not affect apoptosis and heat shock protein 70 level in peripheral blood mononuclear cells from young and old donors
Tian F et al. (2002): Exposure to 2.45 GHz electromagnetic fields induces hsp70 at a high SAR of more than 20 W/kg but not at 5W/kg in human glioma MO54 cells

HSP70 expression in human trophoblast cells exposed to different 1.8 Ghz mobile phone signals med./bio.

Aim of study (acc. to author)

Background/further details

Endpoint

Exposure

Exposure 1

Main characteristics

Modulation

Exposure setup

Parameters

Additional parameter details

Measurement and calculation details

Exposure 2

Main characteristics

Modulation

Exposure setup

Parameters

Exposure 3

Main characteristics

Modulation

Exposure setup

Parameters

Reference articles

Methods Endpoint/measurement parameters/methodology

Main outcome of study (acc. to author)

Study funded by

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