Medical/biological study (experimental study)

Absence of direct effect of low-power millimeter-wave radiation at 60.4 GHz on endoplasmic reticulum stress med./bio.

By: Nicolaz CN, Zhadobov M, Desmots F, Sauleau R, Thouroude D, Michel D, Le Drean Y

Published in: Cell Biol Toxicol 2009; 25 (5): 471-478

Aim of study (acc. to author)

To study the potential effects of low-power millimeter wave exposure on cellular physiology (endoplasmic reticulum stress).

Background/further details

The frequency range of 60 GHz was considered in the context of their near-future applications in wireless communication systems. The endoplasmic reticulum is an organelle sensitive to a wide variety of environmental insults and involved in a number of pathologies and it is the site of synthesis and folding of secreted proteins. Perturbations of endoplasmic reticulum functions and the resulting induced pathway involves different transmembrane proteins or transcription factors (e.g. ATF6, XBP-1) which activate specific genes, such as the chaperone BiP/GRP78.
Separated transfection complexes were used: Cells were transfected with pSEAP (secreted alkaline phosphatase) reporter plasmid as marker for endoplasmic reticulum stress. This reporter enzyme is folded into its active conformation inside the endoplasmic reticulum, and only the correctly folded proteins are secreted into the medium.
Cells were transfected with BiP promoter-reporter plasmid to study stress-involved transcription factors XBP-1 and ATF6.
As endoplasmic reticulum-stress positive control, cells were treated for with thapsigargin or brefeldin or dimethyl sulfoxide.

Endpoint

endoplasmic reticulum stress (gene expression of stress involved transcription factors or genes and endoplasmic reticulum protein folding and secretion)

Exposure

- 60.4 GHz
- millimeter waves

Exposure	Parameters
Exposure 1: 60.43 GHz Modulation type: CW Exposure duration: continuous for 24 h, 48 h or 72 h	power density: 0.14 mW/cm²

Exposure 1

Main characteristics

Frequency	60.43 GHz
Type	electromagnetic field
Polarization	linear
Exposure duration	continuous for 24 h, 48 h or 72 h

Modulation

Modulation type	CW

Exposure setup

Exposure source	horn antenna waveguide
Setup	rectangular waveguide and pyramidal horn antenna located inside an incubator; culture plates placed in the upper part of the incubator above the antenna
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
power density	0.14 mW/cm²	-	-	-	-

Reference articles

Zhadobov M et al. (2007): Low-power millimeter wave radiations do not alter stress-sensitive gene expression of chaperone proteins

Exposed system:

intact cell/cell culture
U-251 MG (human astrocytoma cell line), transfected with ATF6 expression vector, reporter plasmid containing human BiP/GRP78 gene promotor, reporter plasmid pSEAP or luciferase reporter enzyme under control of promoter containing stress response elements

Methods Endpoint/measurement parameters/methodology

molecular biosynthesis: gene expression of stress involved transcription factors XBP1 and ATF6 and of stress-specific sensor gene BiP/GRP78 and HSP70 (quantitative RT-PCR)
endoplasmic reticulum stress (gene expression of stress involved transcription factors or genes (see "molecular biosynthesis") and endoplasmic reticulum protein folding and secretion with SEAP (secreted alkaline phosphatase) enzyme activity as marker

Investigated system:

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

Time of investigation:

after exposure

Main outcome of study (acc. to author)

Exposure to 60.4 GHz did not modify endoplasmic reticulum protein folding and secretion, nor induced XBP1 or ATF6 transcription factors maturation. There was no significant changes in gene expression of BiP/GRP78 and HSP70.
The data show that endoplasmic reticulum homeostasis does not undergo any modification at molecular level after exposure to low-power millimeter wave exposure at 60.4 GHz.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

Association pour la Recherche sur le Cancer (ARC), France
Health and Radiofrequencies Foundation (La Fondation Santé et Radiofréquences), France
Ministère délégué à l'Enseignement supérieur et à la Recherche (Ministry of National Education and Research), France
National Research Agency (L'Agence nationale de la recherche, ANR), France

Nicolaz CN et al. (2009): Study of narrow band millimeter-wave potential interactions with endoplasmic reticulum stress sensor genes
Ramundo-Orlando A et al. (2009): The response of giant phospholipid vesicles to millimeter waves radiation
Zhadobov M et al. (2007): Low-power millimeter wave radiations do not alter stress-sensitive gene expression of chaperone proteins
Ramundo-Orlando A et al. (2007): Permeability changes induced by 130 GHz pulsed radiation on cationic liposomes loaded with carbonic anhydrase
Zhadobov M et al. (2006): Interactions between 60-GHz millimeter waves and artificial biological membranes: dependence on radiation parameters
Somosy Z (2000): Radiation response of cell organelles