To study the effects of prolonged exposure to non-ionizing, low to moderate intensity nanopulses on the growth of pre-neoplastic CL-S1 mammary epithelial cells in vitro. Additional studies investigated the effects of nanopulse exposure on the activation of the mitogen-activated protein kinase (MAPK) mitogenic signalling pathway in these cells.
Electromagnetic ultra-wideband pulses or nanopulses, are generated by a wide range of electronic devices used in communications, radar technology, and high-powered microwave weapons.
Cells were grown in culture medium containing 10 ng/ml EGF (epidermal growth factor) and 10 µg/ml insulin as co-mitogens.
Exposure duration: continuous for 1/4, 1, 2 and 4 hours
Exposure duration: continuous for 4 hours
Exposure duration: continuous for 1, 2, 3, 4, 5 and 6 hours
All experiments were repeated at least three times.
|Chamber||The exposure setup was installed in a copper plate shielded room with an attenuation of 85 dB at 10 GHz. Ancillary equipment was located in a second copper mesh shielded room.|
|Setup||Biological samples were placed in the temperature-controlled (27 °C) gigahertz transverse electromagnetic mode (GTEM) cell and exposed to nanopulses of defined properties. These pulses are non-ionizing and do not cause sample heating.|
|Sham exposure||A sham exposure was conducted.|
|Pulse width||10 ns|
|Rise time||0.1 ns|
|Repetition frequency||1 kHz|
The data showed that 0.25-3.0 h exposure to nanopulses (18 kV/m field intensity, 1 kHz repetition rate, 10 ns pulse width) had no effect on cell growth or cell viability during the subsequent 72-h culture period. However, exposure to similar nanopulses for prolonged periods of time (4-6 h) resulted in a significant increase in cell proliferation, as compared to untreated controls.
Nanopulse exposure enhanced cell growth when cells were maintained in media containing only EGF, but had no effect on cells maintained in defined media that were mitogen-free or containing only insulin.
The findings also revealed that the growth-promoting effects of nanopulse exposure were associated with a relatively large increase in intracellular levels of phospho-MEK1 and phospho-ERK1/2 in these cells.
These results demonstrate that prolonged exposure to moderate levels of ultra-wideband pulses enhanced EGF-dependent mitogenesis, and that this growth-promoting effect appears to be mediated by enhanced activation of the mitogen-activated protein kinase signalling pathway in these cells.