Auteurs

Sekijima M, Takeda H, Yasunaga K, Sakuma N, Hirose H, Nojima T, Miyakoshi J. 2-GHz Band CW and W-CDMA Modulated Radiofrequency Fields Have No Significant Effect on Cell Proliferation and Gene Expression Profile in Human Cells. J Radiat Res (Tokyo). Mar 9, 2010. Ahead of print.

Introduction
Cells adjust to environmental changes by altering gene expression patterns. Studying alterations in gene expression under exposure to radiofrequency (RF) signals can help determine mechanisms by which RF fields act on cells.

Objective
The aim of this study was to investigate cell proliferation and changes in gene expression profile in three human cell lines following exposure to 2.1425 GHz continuous wave (CW) and Wideband-Code Division Multiple Access (W-CDMA) RF fields at three SAR levels.

Methods
Three human cell lines were used in these experiments: A172 (glioblastoma, H4 (neuroglioma) and IMR-90 (fibroblasts from normal fetal lung). Cells were exposed to CW or W-CDMA modulated RF signal at SAR of 80, 250 or 800 mW/kg or sham-exposed for a period of 24, 48, 72 and 96 hours. Heat shock treatment (incubation for 24, 48 or 72 hours at 39°C or 41°C) was used as a positive control. Total cells in cultures were determined by counting with a hemocytometer. Viable cells were measured by trypan blue dye exclusion. Gene expression was determined 96 hours after exposure using the Affymetrix human genome array.

Results
There were no significant differences in cell morphology or cell growth between RF-exposed and sham exposed cells of any line under any exposure conditions. Proliferation profile of the cells subjected to heat treatment (41°C) was different from cells incubated at 37°C. Out of ~ 16,000 to ~18,000 “present” genes, expression of 8 genes in H4 cells, 5 genes in A172 cells and 1 gene in IMR-90 was changed two-fold or more. In contrast, a total of 108 genes were significantly up or down-regulated under the heat treatment conditions.

Interpretation and Conclusion
The results suggest that exposure to 2.1425 GHz RF field at the ICNIRP limit of the average whole-body SAR does not elicit a general stress response in the tested cell lines under the conditions used in these experiments.

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