Downloaded by COLUMBIA UNIV on July 31, 2012 | http://pubs.acs.org Publication Date: May 5, 1995 | doi: 10.1021/ba-1995-0250.ch023
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Biosynthetic Stress Response in Cells Exposed to Electromagnetic Fields 1
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Reba Goodman and Martin Blank 1
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Departments of Pathology and Physiology , Columbia University, New York, NY 10032
The biosynthetic response of cells exposed to electromagnetic (EM) fields has been studied at both transcriptional and translational lev els. In addition to changes in the steady-state levels ofseveral genes, including the protooncogenes c-myc and c-fos, increased transcript levels for the heat shock (stress) gene, HSP70, have been measured in samplesfromcells exposed to EMfieldsin the absence of elevated temperatures. Furthermore, the distribution patterns of proteins synthesized in response to EMfieldsresemble those following heat shock (HS). The cell responds to both EM andHSstimuli in a similar way, and the same sequence of changes with increasing energy oc curs, even though the energies of the two stimuli differ by many or dersof magnitude. When EM and HS stimuli are given simultane ously or sequentially, the protein biosynthetic response is indistinguishablefromthat of either HS or EMfieldalone. Results suggest that EMfieldsstimulate a pathway that is similar to the one used by cells in response to thermal shock and other stresses. EM fields appear to induce the normal biological response to stressful conditions, and this apparent interaction has implications for possi ble health effects.
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X T R E M E L Y L O W F R E Q U E N C Y (ELF) electromagnetic (EM) fields, present in all environments, may pose health risks. Epidemiological studies have shown (1-3) a lçw but significant risk of cancers in populations exposed to
0065-2393/95/0250-0423$12.00/0 © 1995 American Chemical Society In Electromagnetic Fields; Blank, M.; Advances in Chemistry; American Chemical Society: Washington, DC, 1995.
Downloaded by COLUMBIA UNIV on July 31, 2012 | http://pubs.acs.org Publication Date: May 5, 1995 | doi: 10.1021/ba-1995-0250.ch023
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ELECTROMAGNETIC FIELDS
power-frequency (50- and 60-Hz) E M fields. Although several interpretations of the epidemiological data are possible, studies have shown that risk ratios cluster around 2, and in some occupational settings ratios of 6 and higher have been reported (4, 5). A recent study from Sweden (6) reported that the frequency of childhood leukemia increased approximately 2.7 times in homes in which the calculated average magnetic field exceeded 2 m G (0.2 μΤ) and that exposures above 3 m G increased the risk ratio to 3.8 (6). Occupational studies on seam stresses who use electric sewing machines for many years show a 4-6-fold in crease in the incidence of Alzheimer's disease among this population (7). The persistence and weight of the epidemiological findings demand the discovery of a biologically plausible mechanism. The likelihood that E M fields may affect humans is strengthened by evi dence that time-varying E M fields have beneficial effects in accelerating the healing of bone fracture nonunions (8). To date, questions of E M field interac tions with cells and their possible relation to cancer, as well as their clinical ef fectiveness, have motivated scientists to seek explanations for how these fields cause changes in cells. E L F E M fields (
