HTR-8/Svneo human trophoblast cells were exposed to 1800 MHz (GSM, CW) RF at 2 W/kg for 1, 16, 24, or 48 hours and evaluated for gene expression changes. 43 degree heat shock was used as a positive control. The authors initially report no effect on DNA damage using alkaline comet assay, differential expression of heat shock genes, or protein activation. In a follow-on study, the authors again exposed human trophoblasts to 1800 MHz at 2 W/kg using GSM, GSM + DTx, and CW modulations for 4 or 24 hours. No effects on viability or HSP70A or HSP70B gene expression were observed from any exposure, but HSP70C expression was increased with 24hr exposure to GSM signals and significantly reduced with 4 and 16 hour GSM+DTx signals. DNA strand breaks were also increased with both GSM and GSM + DTx signals. No effect was observed with CW exposure. The authors suggest the modulation scheme may play a role in the effect.
AUTHORS' ABSTRACT: Valbonesi et al. 2014 (IEEE #5774): PURPOSE: We previously reported effects on heat shock protein 70 (HSP70) mRNA expression, a cytoprotective protein induced under stressful condition, in human trophoblast cells exposed to amplitude-modulated Global System for Mobile Communication (GSM) signals. In the present work the same experimental conditions were applied to the rat PC12 cells, in order to assess the stress responses mediated by HSP70 and by the Mitogen Activated Protein Kinases (MAPK) in neuronal-like cells, an interesting model to study possible effects of mobile phone frequencies exposure.
MATERIALS AND METHODS: HSP70 gene expression level was evaluated by reverse transcriptase polymerase chain reaction, HSP70 protein expression and MAPK phosphorylation were assessed by Western blotting. PC12 cells were exposed for 4, 16 or 24 h to 1.8 GHz continuous wave signal (CW, carrier frequency without modulation) or to two different GSM modulation schemes, GSM-217Hz and GSM-Talk (which generates temporal changes between two different GSM signals, active during talking or listening phases, respectively, thus simulating a typical conversation). Specific adsorption rate (SAR) was 2 W/kg.
RESULTS: After PC12 cells exposure to the GSM-217Hz signal for 16 or 24 h, HSP70 transcription significantly increased, whereas no effect was observed in cells exposed to the CW or GSM-Talk signals. HSP70 protein expression and three different MAPK signaling pathways were not affected by the exposure to any of the three different 1.8 GHz signals.
CONCLUSION: The positive effect on HSP70 mRNA expression, observed only in cells exposed to the GSM-217Hz signal, is a repeatable response previously reported in human trophoblast cells and now confirmed in PC12 cells. Further investigations towards a possible role of 1.8 GHz signal modulation are therefore advisable.
AUTHORS' ABSTRACT: Valbonesi et al 2016 (IEEE #6292): Purpose Due to its role in learning, memory and in many neurodegenerative diseases, acetylcholinesterase (AChE) represents an interesting endpoint to assess possible targets of exposure to radiofrequency electromagnetic fields (RF-EMF) generated by mobile phones. We investigated possible alterations of enzymatic activity, gene and protein expression of AChE in neuronal-like cells exposed to a 1.8 GHz Global System for Mobile Communication (GSM) modulated signal (217-GSM). Materials and methods Rat PC12 cells were exposed for 24 h to 1.8 GHz 217-GSM signal. Specific adsorption rate (SAR) was 2 W/kg. AChE enzyme activity was assessed spectrophotometrically by Ellman's method, mRNA expression level was evaluated by real time polymerase chain reaction, and protein expression was assessed by Western blotting. Results AChE enzymatic activity increased of 1.4-fold in PC12 cells exposed to 217-GSM signal for 24 h, whilst AChE transcriptional or translational pathways were not affected. Conclusion Our results provide the first evidence of effects on AChE activity after in vitro exposure of mammalian cells to the RF-EMF generated by GSM mobile phones, at the SAR value 2 W/kg. The obtained evidence promotes further investigations on AChE as a possible target of RF-EMF and confirm the ability of 1.8 GHz 217-GSM signal to induce biological effects in different mammalian cells.