Extremely Low Frequency Magnetic Fields Increase the Expression of HIF-1α in Prostate Cancer Cells
Author(s): Sharon Amir, Snir Dekalo, Joseph Friedman, Nicola J Mabjeesh
Background: Increased levels of hypoxia-inducible factor 1α (HIF-1α) are related to poor prognosis and treatment failure in prostate cancer. The effect of extremely low frequency magnetic fields (ELF-MF), generally emitted from electronic devices on HIF-1α in cancer cells and, specifically, in prostate cancer is not well described. This study aimed to investigate the effects of ELF-MF on HIF- 1α protein expression and HIF-1 transcriptional activity in prostate cancer cells.
Methods: Prostate cancer cells were irradiated with ELF-MF by means of a frequency generator at 875 MHz with an intensity of 0.07 mW/cm2 at various time periods and with an exposure system housed in a tissue culture incubator. The expression of HIF-1α protein and HIF-1 transcriptional activity at the different conditions were evaluated.
Results: HIF-1α expression in different prostate cancer cells was higher after one hour of exposure to ELF-MF. All exposed cells also demonstrated a significant 50% increase in HIF-1 transcriptional activity as measured by an HRE-dependent reporter gene assay after ELF-MF irradiation. Cells exposed to ELF-MF exhibited 3-fold longer HIF-1α half-life compared to non-exposed control cells, while its mRNA levels were not affected. Immunofluorescence staining confirmed nuclear HIF-1α accumulation following exposure to ELF-MF. Cell proliferation was increased following ELF-MF exposure and significantly reduced when HIF-1α was silenced even after exposure to ELF-MF.
Conclusions: Exposure of prostate cancer cells to ELF-MF increases HIF-1α protein stability and upregulates HIF-1 transcriptional activity. These findings provide new insights into the effects of ELF-MF on the hypoxic pathway which are important for guiding future implications.