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Exposure to specific electromagnetic field (EMF) patterns can affect a variety of biological systems. We have shown that exposure to Thomas-EMF, a low-intensity, frequency-modulated (25-6 Hz) EMF pattern, inhibited growth and altered cell signaling in malignant cells. Exposure to Thomas-EMF for 1 h/day inhibited the growth of malignant cells including B16-BL6 mouse melanoma cells, MDA-MB-231, MDA-MB-468, BT-20, and MCF-7 human breast cancer and HeLa cervical cancer cells but did not affect non-malignant cells. The Thomas-EMF-dependent changes in cell proliferation were mediated by adenosine 3',5'-cyclic monophosphate (cAMP) and extracellular-signal-regulated kinase (ERK) signaling pathways. Exposure of malignant cells to Thomas-EMF transiently changed the level of cellular cAMP and promoted ERK phosphorylation. Pharmacologic inhibitors (SQ22536) and activators (forskolin) of cAMP production both blocked the ability of Thomas-EMF to inhibit cell proliferation, and an inhibitor of the MAP kinase pathway (PD98059) was able to partially block Thomas-EMF-dependent inhibition of cell proliferation. Genetic modulation of protein kinase A (PKA) in B16-BL6 cells also altered the effect of Thomas-EMF on cell proliferation. Cells transfected with the constitutively active form of PKA (PKA-CA), which interfered with ERK phosphorylation, also interfered with the Thomas-EMF effect on cell proliferation. The non-malignant cells did not show any EMF-dependent changes in cAMP levels, ERK phosphorylation, or cell growth. These data indicate that exposure to the specific Thomas-EMF pattern can inhibit the growth of malignant cells in a manner dependent on contributions from the cAMP and MAP kinase pathways. Bioelectromagnetics. 39;217-230, 2018. © 2017 Wiley Periodicals, Inc., (© 2017 Wiley Periodicals, Inc.)

Exposure to low intensity, low frequency electromagnetic fields (EMF) has effects on several biological systems. Spatiotemporal characteristics of these EMFs are critical. The effect of several complex EMF patterns on the proliferation of B16-BL6 mouse melanoma cells was tested. Exposure to one of these patterns, the Thomas-EMF, inhibited cell proliferation and promoted calcium uptake. The Thomas-EMF is coded from a digital-to-analog file comprised of 849 points, which provides power to solenoids and can be set to alter timing, intensity, and duration of variable EMF. Setting the point duration to 3 ms generated a time-varying EMF pattern which began at 25 Hz and slowed to 6 Hz over a 2.5 s repeat. Exposing B16-BL6 cells to Thomas-EMF set to 3 ms for 1 h/day inhibited cell proliferation by 40% after 5 days, while setting the point duration to 1, 2, 4, or 5 ms had no effect on cell proliferation. Similarly, exposing cells to Thomas-EMF set to 3 ms promoted a three-fold increase in calcium uptake after 1 h, while the other timings had no effect. Exposure to Thomas-EMF for as short as 15 min/day slowed cell proliferation, but exposure for 1 h/day was optimal. This corresponded to the effect on calcium uptake where uptake was detected after 15 min exposure and was maximal by 1 h of treatment. Studies show that the specific spatiotemporal character of EMF is critical in mediating their biological activities. Bioelectromagnetics. 38:165-174, 2017. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)

Electromagnetic field (EMF) exposures affect many biological systems. The reproducibility of these effects is related to the intensity, duration, frequency, and pattern of the EMF. We have shown that exposure to a specific time-varying EMF can inhibit the growth of malignant cells. Thomas-EMF is a low-intensity, frequency-modulated (25-6 Hz) EMF pattern. Daily, 1 h, exposures to Thomas-EMF inhibited the growth of malignant cell lines including B16-BL6, MDA-MB-231, MCF-7, and HeLa cells but did not affect the growth of non-malignant cells. Thomas-EMF also inhibited B16-BL6 cell proliferation in vivo. B16-BL6 cells implanted in syngeneic C57b mice and exposed daily to Thomas-EMF produced smaller tumours than in sham-treated controls. In vitro studies showed that exposure of malignant cells to Thomas-EMF for > 15 min promoted Ca(2+) influx which could be blocked by inhibitors of voltage-gated T-type Ca(2+) channels. Blocking Ca(2+) uptake also blocked Thomas-EMF-dependent inhibition of cell proliferation. Exposure to Thomas-EMF delayed cell cycle progression and altered cyclin expression consistent with the decrease in cell proliferation. Non-malignant cells did not show any EMF-dependent changes in Ca(2+) influx or cell growth. These data confirm that exposure to a specific EMF pattern can affect cellular processes and that exposure to Thomas-EMF may provide a potential anti-cancer therapy.