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Biao Shi,¹ Behnom Farboud,² Richard Nuccitelli,² and R. Rivkah Isseroff¹

¹Department of Dermatology and ²Section of Molecular and Cellular Biology, University of California-Davis, Davis, California, USA

Abstract

The linkage of the exposure to the power-line frequency (50-60 Hz) electromagnetic fields (EMF) with human cancers remains controversial after more than 10 years of study. The in vitro studies on the adverse effects of EMF on human cells have not yielded a clear conclusion. In this study, we investigated whether power-line frequency EMF could act as an environmental insult to invoke stress responses in human keratinocytes using the 27-kDa heat shock protein (HSP27) as a stress marker. After exposure to 1 gauss (100 µT) EMF from 20 min to 24 hr, the isoform pattern of HSP27 in keratinocytes remained unchanged, suggesting that EMF did not induce the phosphorylation of this stress protein. EMF exposure also failed to induce the translocation of HSP27 from the cytoplasm to the nucleus. Moreover, EMF exposure did not increase the abundance of HSP27 in keratinocytes. In addition, we found no evidence that EMF exposure enhanced the level of the 70-kDa heat shock protein (HSP70) in breast or leukemia cells as reported previously. Therefore, in this study we did not detect any of a number of stress responses in human keratinocytes exposed to power-line frequency EMF. Key words: electromagnetic fields, heat shock proteins, HSP70, HSP27 phosphorylation, HSP27 translocation, keratinocytes, signal transduction, stress. Environ Health Perspect 111:281-287 (2003) .