Effects of extremely low frequency electromagnetic field and cisplatin on mRNA levels of some DNA repair genes

- mRNA levels of seven genes involved in DNA repair pathways were evaluated.
- The examined genes had tendency to be down-regulated in the cells treated with EMF.
- GADD45A mRNA levels in cells co-treated with cisplatin (CDDP) + EMF were increased.
- Co-treatment of CDDP + EMF enhances down-regulation of the genes of NHEJ pathway.
- Elevation in IC50 of CDDP when cells co-treated with CDDP + EMF was observed.

AimsIt has been shown that exposure to extremely-low frequency (˂300 Hz) oscillating electromagnetic field (EMF) can affect gene expression. The effects of different exposure patterns of 50-Hz EMF and co-treatment of EMF plus cisplatin (CDDP) on mRNA levels of seven genes involved in DNA repair pathways (GADD45A, XRCC1, XRCC4, Ku70, Ku80, DNA-PKcs and LIG4) were evaluated.Main methodsTwo 50-Hz EMF intensities (0.25 and 0.50 mT), three exposure patterns (5 min field-on/5 min field-off, 15 min field-on/15 min field-off, 30 min field-on continuously) and two cell lines (MCF-7 and SH-SY5Y) were used. The mRNA levels were measured using quantitative real-time PCR.Key findingsThe examined genes had tendency to be down-regulated in MCF-7 cells treated with EMF. In the pattern of 15 min field-on/15 min field-off of the 0.50 mT EMF, no increase in mRNA levels were observed, but the mRNA levels of GADD45A, XRCC1, XRCC4, Ku80, Ku70, and LIG4 were down-regulated. A significant elevation in IC50 of CDDP was observed when MCF-7 and SH-SY5Y cells were co-treated with CDDP + EMF in comparison with the cells treated with CDDP alone. GADD45A mRNA levels in MCF-7 and SH-SY5Y cells co-treated with CDDP + EMF were increased and at the same time the mRNA levels of XRCC4, Ku80, Ku70 and DNA-PKcs were down-regulated.SignificancePresent study provides evidence that co-treatment of CDDP + EMF can enhance down-regulation of the genes involved in non-homologous end-joining pathway. It might be suggested that co-treatment of CDDP + EMF could be more promising for sensitizing cancer cells to DNA double strand breaks.