title: Distinct epidermal keratinocytes respond to extremely low-frequency electromagnetic fields differently.
abstract: Following an increase in the use of electric appliances that can generate 50 or 60 Hz electromagnetic fields, concerns have intensified regarding the biological effects of extremely low-frequency electromagnetic fields (ELF-EMFs) on human health. Previous epidemiological studies have suggested the carcinogenic potential of environmental exposure to ELF-EMFs, specifically at 50 or 60 Hz. However, the biological mechanism facilitating the effects of ELF-EMFs remains unclear. Cellular studies have yielded inconsistent results regarding the biological effects of ELF-EMFs. The inconsistent results might have been due to diverse cell types. In our previous study, we indicated that 1.5 mT, 60 Hz ELF-EMFs will cause G1 arrest through the activation of the ATM-Chk2-p21 pathway in human keratinocyte HaCaT cells. The aim of the current study was to investigate whether ELF-EMFs cause similar effects in a distinct epidermal keratinocyte, primary normal human epidermal keratinocytes (NHEK), by using the same ELF-EMF exposure system and experimental design. We observed that ELF-EMFs exerted no effects on cell growth, cell proliferation, cell cycle distribution, and the activation of ATM signaling pathway in NHEK cells. We demonstrated that the 2 epidermal keratinocytes responded to ELF-EMFs differently. To further validate this finding, we simultaneously exposed the NHEK and HaCaT cells to ELF-EMFs in the same incubator for 168 h and observed the cell growths. The simultaneous exposure of the two cell types results showed that the NHEK and HaCaT cells exhibited distinct responses to ELF-EMFs. Thus, we confirmed that the biological effects of ELF-EMFs in epidermal keratinocytes are cell type specific. Our findings may partially explain the inconsistent results of previous studies when comparing results across various experimental models.
authors.affiliation: Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan.
authors.forename: Chao-Ying
authors.initials: CY
authors.lastname: Huang
authors.affiliation: Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan.
authors.forename: Chun-Yu
authors.initials: CY
authors.lastname: Chuang
authors.affiliation: Institute of Statistics, National Tsing Hua University, Hsinchu, Taiwan.
authors.forename: Wun-Yi
authors.initials: WY
authors.lastname: Shu
authors.affiliation: Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan.
authors.forename: Cheng-Wei
authors.initials: CW
authors.lastname: Chang
authors.affiliation: Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan.
authors.forename: Chaang-Ray
authors.initials: CR
authors.lastname: Chen
authors.affiliation: Magnet Group, Instrumentation Development Division, National Synchrotron Radiation Research Center, Hsinchu, Taiwan.
authors.forename: Tai-Ching
authors.initials: TC
authors.lastname: Fan
authors.affiliation: Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan.
authors.forename: Ian C
authors.initials: IC
authors.lastname: Hsu
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins / Q000378:metabolism; D049109:Cell Proliferation / Q000528:radiation effects; D002478:Cells, Cultured; D064447:Checkpoint Kinase 2 / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D004574:Electromagnetic Fields; D000078404:Epidermal Cells; D059585:G1 Phase Cell Cycle Checkpoints / Q000528:radiation effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000633:toxicity; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects*; D010766:Phosphorylation / Q000187:drug effects; D015398:Signal Transduction / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D050759:Cyclin-Dependent Kinase Inhibitor p21; D006861:Hydrogen Peroxide; D064447:Checkpoint Kinase 2; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C578634:CHEK2 protein, human