Do 50/60 Hz magnetic fields influence oxidative or DNA damage responses in human SH-SY5Y neuroblastoma cells?

Abstract

Purpose

We investigated the possible effects of 50 and 60 Hz magnetic fields (MFs) on reactive oxygen species (ROS) production, DNA damage, DNA damage repair rate, as well as gene expression related to oxidative stress and DNA damage signaling.

Materials and methods

Human SH-SY5Y neuroblastoma cells were sham-exposed or exposed to 100 µT_RMS MFs for 24 h, then assayed or further treated with 100 µM menadione for 1 h before the assay. The levels of ROS and cytosolic superoxide anion (O₂^•–) were assayed fluorometrically. DNA damage and gene expression were assayed by comet assay and RT-qPCR, respectively. To examine whether MFs affected DNA damage repair rate, cells were allowed to repair their DNA for 1 or 2 h after menadione treatment and then assayed for DNA damage.

Results

There was suggestive evidence of a general low-magnitude increase in the expression of ROS-related genes (primarily genes with antioxidant activity) when quantified immediately after MF exposure, suggesting a response to a small increase in ROS level. The possible upregulation of ROS-related genes is supported by the finding that the level of menadione-induced ROS was consistently decreased by 50 Hz MFs (not significantly by 60 Hz MFs) in several measurements 30–60 min after MF exposure. MF exposures did not affect cytosolic O₂^•– levels, DNA damage, or its repair rate. Changes in the expression of DNA damage-signaling genes in the MF-exposed cells did not exceed the expected rate of false-positive findings. No firm evidence was found for differential effects from 50 vs. 60 Hz MFs.

Conclusions

While only weak effects were found on the endpoints measured, the results are consistent with MF effects on ROS signaling.

Keywords:

• Extremely low-frequency magnetic fields
• reactive oxygen species (ROS)
• DNA damage
• DNA repair

Acknowledgments

We want to thank senior laboratory technician Ms. Hanne Vainikainen for her expert technical assistance.

Disclosure statement

The authors report no conflict of interest.

Additional information

Funding

This study was funded by the Academy of Finland (grant number 298378) and UEF Doctoral Programme in Environmental Physics, Health and Biology.

Notes on contributors

Ehab Mustafa

Ehab Mustafa, M.Sc., is an early-stage researcher (and Ph.D. candidate) in Radiation Research Group at the Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio, Finland.

Leonardo Makinistian

Leonardo Makinistian, Ph.D., is an adjoint professor at the Department of Physics of the Universidad Nacional de San Luis (UNSL, San Luis, Argentina) and an adjoint researcher, head of the Laboratory of Magnetobiology (MBLab) of the Applied Physics Institute (INFAP), at UNSL-National Council of Scientific and Technical Research (CONICET), San Luis, Argentina.

Jukka Luukkonen

Jukka Luukkonen, Ph.D., is a university lecturer at the Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio, Finland.

Jukka Juutilainen

Jukka Juutilainen, Ph.D., is a professor emeritus at the Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio, Finland.

Jonne Naarala

Jonne Naarala, Ph.D., is an associate professor of radiation biology and leader of Radiation Research Group at the Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio, Finland.