Decreased DNA repair rates and protection from heat induced apoptosis mediated by electromagnetic field exposure

Abstract

In this study, we demonstrate that electromagnetic field (EMF) exposure results in protection from heat induced apoptosis in human cancer cell lines in a time dependent manner. Apoptosis protection was determined by growing HL-60, HL-60R, and Raji cell lines in a 0.15 mT 60 Hz sinusoidal EMF for time periods between 4 and 24 h. After induction of apoptosis, cells were analyzed by the neutral comet assay to determine the percentage of apoptotic cells. To discover the duration of this protection, cells were grown in the EMF for 24 h and then removed for 24 to 48 h before heat shock and neutral comet assays were performed. Our results demonstrate that EMF exposure offers significant protection from apoptosis (P<.0001 for HL-60 and HL-60R, P<.005 for Raji) after 12 h of exposure and that protection can last up to 48 h after removal from the EMF. In this study we further demonstrate the effect of the EMF on DNA repair rates. DNA repair data were gathered by exposing the same cell lines to the EMF for 24 h before damaging the exposed cells and non-exposed cells with H2O2. Cells were allowed to repair for time periods between 0 and 15 min before analysis using the alkaline comet assay. Results showed that EMF exposure significantly decreased DNA repair rates in HL-60 and HL-60R cell lines (P<.001 and P<.01 respectively), but not in the Raji cell line. Importantly, our apoptosis results show that a minimal time exposure to an EMF is needed before observed effects. This may explain previous studies showing no change in apoptosis susceptibility and repair rates when treatments and EMF exposure were administered concurrently. More research is necessary, however, before data from this in vitro study can be applied to in vivo systems.

Inducing salt tolerance in sweet corn by magnetic priming

“…The mechanism of such detrimental effects of exposing to strong magnetic fields or prolonged MF treatments are unknown; however, MF may induce mutation and DNA damage in plant (Ager and Radul, 1992) and other organisms (Zmyslony et al, 2000). Robison et al (2002) also showed that electromagnetic treatments decrease DNA repair rate. On the other hand, lower seeds germination and seedlings growth can be related to overproduction of hydrogen peroxide in plant and increased lipid oxidation after exposing seeds to stronger MF or prolonged MF treatments (Podleoeny et al, 2005).…”

DNA Lesion-specific Co-localization of the Mre11/Rad50/Nbs1 (MRN) Complex and Replication Protein A (RPA) to Repair Foci

“…Comet Assays-Neutral comet assays were performed as described previously (61,62) with slight modifications. 12,000 -15,000 cells from treated cultures were suspended in low-melting point agarose in PBS (Invitrogen, final concentration of 0.75%) and layered on microscope slides.…”

Effect of seed pretreatment by magnetic field on the sensitivity of cucumber (Cucumis sativus) seedlings to ultraviolet-B radiation

“…Previous study demonstrated that electromagnetic treatment decreased DNA repair rates in human cancer cell lines (Robison et al, 2002). MF could also induce plant mutation (Ager and Radul, 1992) and UV-B irradiation could produce cyclobutane dimers (CPD) and (6-4) photoproducts in plant DNA (Britt, 1996).…”