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

Abstract

Millimeter waves (MMW) at frequencies around 60 GHz will be used in the very near future in the emerging local wireless communication systems and the potential health hazards of artificially induced environmental exposures represent a major public concern. The main aim of this study was to investigate the potential effects of low-power MMW radiations on cellular physiology. To this end, the human glial cell line, U-251 MG, was exposed to 60.4 GHz radiation at a power density of 0.14 mW/cm(2) and potential effect of MMW radiations on endoplasmic reticulum (ER) stress was investigated. ER is very sensitive to environmental insults and its homeostasis is altered in various pathologies. Through several assay systems, we found that exposure to 60.4 GHz does not modify ER protein folding and secretion, nor induces XBP1 or ATF6 transcription factors maturation. Moreover, expression of ER-stress sensor, BiP/GRP78 was examined by real-time PCR, in exposed or non-exposed cells to MMW radiations. Our data demonstrated the absence of significant changes in mRNA levels for BiP/GRP78. Our results showed that ER homeostasis does not undergo any modification at molecular level after exposure to low-power MMW radiation at 60.4 GHz. This report is the first study of ER-stress induction by MMW radiations.

Impact of 60‐GHz millimeter waves and corresponding heat effect on endoplasmic reticulum stress sensor gene expression

“…We measured the mRNA levels of two ER‐resident chaperons, BIP and ORP150 , known to be over expressed during ER stress [Nicolas Nicolaz et al, ]. In HaCaT, TG treatment (1 µM, 16 h) increased the BIP and ORP150 mRNA levels by 12‐ and 8‐fold, respectively (black histograms, Fig.…”

“…Several indications in scientific literature suggest that membrane‐rich cellular organelles, such as ER, could be potential targets of MMW. We previously proved that ER homeostasis does not undergo any modification at molecular level after exposure to low‐power (0.14 mW/cm 2 ) MMW radiations around 60 GHz [Nicolas Nicolaz et al, 2009a,b]. Therefore, it was interesting to further investigate the effects of high‐power MMW, especially for IPD close to the ICNIRP limits set for the general public (1 or 20 mW/cm 2 , depending on exposure scenarios).…”

“…Besides, 30/40‐GHz MMW (4 mW/cm 2 ) exposures were reported to induce enrichment and development of ER in exposed mesenchymal stem cells [Wu et al, ]. However, our group has recently demonstrated that low‐power MMW (0.14 mW/cm 2 ) within 59–61.2 GHz frequency range does not affect the basal ER homeostasis in the human cell line [Nicolas Nicolaz et al, 2009a,b]. The aim of this work is to further investigate the effect of a 60 GHz exposure at various power densities, on basal or stress‐induced expression of ER chaperons BIP and ORP150 , in order to identify possible power thresholds of induced effects and compare them with the thermal thresholds.…”

Calreticulin Protects Rat Microvascular Endothelial Cells against Microwave Radiation‐induced Injury by Attenuating Endoplasmic Reticulum Stress

“…In this study, we found that the protein expression levels of GRP78 and CRT were significantly upregulated in cultured MMECs that were exposed to 2.856 GHz high‐power microwaves at a mean power density of 30 mW/cm 2 for six minutes, which suggests that MR is able to induce marked ER stress. However, the findings of Nicolaz demonstrate that ER homeostasis does not undergo any modification at the molecular level after exposure to low‐power millimeter wave (0.14 mW/cm 2 , 24 hours) at 60.4 GHz in the human glial cell line U‐251 MG . The reason for this inconsistency may be the difference in frequency and power of the microwaves used in the different experiments.…”

Effects of Long-Term Exposure to 60 GHz Millimeter-Wavelength Radiation on the Genotoxicity and Heat Shock Protein (Hsp) Expression of Cells Derived from Human Eye

“…Beneduci et al [21] showed that long-term exposure of human skin melanoma cells to 42 GHz and 53 GHz radiation at a power density below 0.3 mW/cm 2 did not induce any effect on the cell cycle of these cells. Nicolaz et al [22] described that exposure to 60.4 GHz radiation at a power density of 0.14 mW/cm 2 did not cause endoplasmic reticulum stress in human glial cells. Le Dréan’s group has also published studies on the effects of 60.4 GHz radiation [23,24,25].…”