Chronic electromagnetic field exposure decreases HSP70 levels and lowers cytoprotection

Electromagnetic field (EMF) exposures have been shown to induce heat shock proteins (HSPs), which help to maintain the conformation of cellular proteins during periods of stress. We have previously reported that short‐term exposure of chick embryos to either 60 Hz (extremely low frequency: ELF), or radio‐frequency (RF: 915 MHz) EMFs induce protection against hypoxia. Experiments presented in the current report are based on a study in which long‐term (4 days), continuous exposure to ELF‐EMFs decreased protection against ultraviolet radiation. Based on this result, it was hypothesized that de‐protection against hypoxia should also occur following long‐term, continuous, or daily, repeated exposures to EMFs. To test this hypothesis, chick embryos were exposed to ELF‐EMFs (8 μT) continuously for 4 days, or to ELF or RF (3.5 mW incident power)‐EMFs repeated daily (20, 30, or 60 min once or twice daily for 4 days). Several of the exposure protocols yielded embryos that had statistically significant decreases in protection against hypoxic stress (continuous and 30 or 60 min ELF twice daily; or 30 or 60 min once daily RF). This is consistent with our finding that following 4 days of ELF‐EMF exposure, HSP70 levels decline by 27% as compared to controls. In addition, the superposition of ELF‐EM noise, previously shown to minimize ELF‐EMF induced hypoxia protection, inhibited hypoxia de‐protection caused by long term, continuous ELF or daily, repeated RF exposures. This EMF‐induced decrease in HSP70 levels and resulting decline in cytoprotection suggests a mechanism by which daily exposure (such as might be experienced by mobile phone users) could enhance the probability of cancer and other diseases. J. Cell. Biochem. 84: 447–454, 2002. © 2001 Wiley‐Liss, Inc.

[1]  L. Feinendegen,et al.  Molecular biology, epidemiology, and the demise of the linear no-threshold (LNT) hypothesis. , 1999, Comptes rendus de l'Academie des sciences. Serie III, Sciences de la vie.

[2]  B. Schmierer,et al.  Endothelial cells downregulate expression of the 70 kDa heat shock protein during hypoxia. , 2000, Biochemical and biophysical research communications.

[3]  Viktor Hamburger,et al.  A series of normal stages in the development of the chick embryo , 1992, Journal of morphology.

[4]  R. Goodman,et al.  Electromagnetic field exposure induces rapid, transitory heat shock factor activation in human cells , 1997, Journal of cellular biochemistry.

[5]  R. Goodman,et al.  Electromagnetic field stimulation of biosynthesis: changes in c-myc transcript levels during continuous and intermittent exposures , 1996 .

[6]  D Krause,et al.  Role of modulation on the effect of microwaves on ornithine decarboxylase activity in L929 cells. , 1997, Bioelectromagnetics.

[7]  T. Litovitz,et al.  The superposition of a temporally incoherent magnetic field inhibits 60 Hz-induced changes in the ODC activity of developing chick embryos. , 1998, Bioelectromagnetics.

[8]  H. Gutzeit,et al.  Electromagnetic fields enhance the stress response at elevated temperatures in the nematode Caenorhabditis elegans. , 2000, Bioelectromagnetics.

[9]  S. Ueno,et al.  Effects of exposure to repetitive pulsed magnetic stimulation on cell proliferation and expression of heat shock protein 70 in normal and malignant cells. , 1999, Biochemical and biophysical research communications.

[10]  T. Litovitz,et al.  Short-term magnetic field exposures (60 Hz) induce protection against ultraviolet radiation damage. , 1999, International journal of radiation biology.

[11]  Martin Blank,et al.  Increased levels of hsp70 transcripts induced when cells are exposed to low frequency electromagnetic fields , 1994 .

[12]  R. Goodman,et al.  Application of magnetic field–induced heat shock protein 70 for presurgical cytoprotection , 1998, Journal of cellular biochemistry.

[13]  B. Greenebaum,et al.  Magnetic field exposure enhances mRNA expression of σ32 in E. coli , 1998 .

[14]  S. Garrett,et al.  Expression of heat shock protein 60 in human proximal tubule cells exposed to heat, sodium arsenite and CdCl2 , 2000 .

[15]  D. Thomas,et al.  Transgenic nematodes as biomonitors of microwave-induced stress. , 1998, Mutation research.

[16]  A. Nakai,et al.  HSF3 is a major heat shock responsive factor duringchicken embryonic development. , 1999, European journal of biochemistry.

[17]  J. Pipkin,et al.  Induction of stress proteins by electromagnetic fields in cultured HL-60 cells. , 1999, Bioelectromagnetics.

[18]  W. E. Koch,et al.  Development of chicken embryos in a pulsed magnetic field. , 1990, Bioelectromagnetics.

[19]  A Pierangeli,et al.  Protective effect of low frequency low energy pulsing electromagnetic fields on acute experimental myocardial infarcts in rats. , 1999, Bioelectromagnetics.

[20]  H. Köhler,et al.  Divergent Kinetics of hsp70 Induction in Oniscus asellus (Isopoda) in Response to Four Environmentally Relevant Organic Chemicals (B[a]P, PCB52, γ-HCH, PCP): Suitability and Limits of a Biomarker , 1999, Archives of environmental contamination and toxicology.

[21]  S. Garrett,et al.  Expression of heat shock protein 60 in human proximal tubule cells exposed to heat, sodium arsenite and CdCl(2). , 2000, Toxicology letters.

[22]  R. Goodman,et al.  Electric and magnetic noise blocks the 60 Hz magnetic field enhancement of steady state c-myc transcript levels in human leukemia cells , 1995 .

[23]  M. Madonna,et al.  Dexamethasone protection of rat intestinal epithelial cells against oxidant injury is mediated by induction of heat shock protein 72. , 1998, The Journal of clinical investigation.

[24]  E Sobel,et al.  Elevated risk of Alzheimer's disease among workers with likely electromagnetic field exposure , 1996, Neurology.

[25]  T. Litovitz,et al.  INTERMITTENT NOISE AFFECTS EMF-INDUCED ODC ACTIVITY , 1998 .

[26]  R. Issels,et al.  Heat shock protein 72 on tumor cells: a recognition structure for natural killer cells. , 1997, Journal of immunology.

[27]  G. Steinberg,et al.  Protection against focal cerebral ischemia following exposure to a pulsed electromagnetic field. , 1994, Bioelectromagnetics.

[28]  S. Garrett,et al.  Expression of the constitutive and inducible forms of heat shock protein 70 in human proximal tubule cells exposed to heat, sodium arsenite, and CdCl(2). , 1999, Environmental health perspectives.

[29]  R. Goodman,et al.  Magnetic field stress induces expression of hsp70. , 1998, Cell stress & chaperones.

[30]  E. Ottaviani,et al.  Reduction of heat‐shock protein‐70 after prolonged treatment with retinoids: Biological and clinical implications , 1997, American journal of hematology.

[31]  J. Murat,et al.  Pattern of stress protein expression in human lung cell-line A549 after short- or long-term exposure to cadmium. , 1999, Environmental health perspectives.

[32]  K. H. Mild,et al.  Cellular and cordless telephones and the risk for brain tumours , 2002, European journal of cancer prevention : the official journal of the European Cancer Prevention Organisation.

[33]  G. Oxenkrug,et al.  Antioxidant and Antiaging Activity of N‐Acetylserotonin and Melatonin in the in Vivo Models , 2001, Annals of the New York Academy of Sciences.

[34]  K Chow,et al.  Magnetic field exposure enhances DNA repair through the induction of DnaK/J synthesis , 2000, FEBS letters.

[35]  H. Laborit,et al.  Antioxidant activity of melatonin in mice. , 1993, Research communications in chemical pathology and pharmacology.

[36]  P. Raskmark,et al.  The minimizing effect of electromagnetic noise on the changes in cell proliferation caused by ELF magnetic fields , 1996 .

[37]  M. Schlesinger.  9 – Stress Response in Avian Cells , 1985 .

[38]  David B. Walden,et al.  Changes in Eukaryotic Gene Expression in Response to Environmental Stress , 1985 .

[39]  T. Litovitz,et al.  Myocardial protection conferred by electromagnetic fields. , 1999, Circulation.

[40]  S. Garrett,et al.  Heat shock protein 27 expression in human proximal tubule cells exposed to lethal and sublethal concentrations of CdCl2. , 1999, Environmental health perspectives.