Gene analysis of HeLa cells subjected to intense burst sinusoidal electric fields

Abstract

Intense pulsed electrics field are one of the agents to give physical stresses to biological systems which are the complex of dielectric materials. We have been using an intense burst sinusoidal electric field (IBSEF) as a narrow band field to discuss the biological effects of the field in the frequency domain. Our previous study demonstrated that the enhancement of proliferation activity of HeLa S3 cells is induced by the application of non-thermal, IBSEF with amplitudes of 300 kV/m and with frequencies between 3 and 100 MHz. Moreover, the application of the smaller number of the pulses enhanced the proliferation activity, whereas the cells were likely to be killed by the larger number of the pulses. According to calculation of the electric field distribution over the cell under AC field, the field strength of cell membrane is decreased with increasing the frequency in the range more than 1 MHz. The range of frequencies between 3–10 MHz, the distributed field strength on nuclear membrane became the maximum. This is because of the decrease in the electrical impedance of the membrane, which can be regarded as a dielectric film. The frequency dependence implies the proliferation activity might be associated with the electric field at the cell membrane and nuclear membrane. Here, we analyze expression of RNA gene related to cell growth including cell cycle and describe the mechanism of the enhancement of proliferation activity by means of reverse transcription polymerase chain reaction (RT-PCR) assays.