Decreased DNA repair rates and protection from heat induced apoptosis mediated by electromagnetic field exposure.

Abstract

In this study, we demonstrate that electromagnetic field (EMF) exposure results in protection from heat induced apoptosis in human cancer cell lines in a time dependent manner. Apoptosis protection was determined by growing HL-60, HL-60R, and Raji cell lines in a 0.15 mT 60 Hz sinusoidal EMF for time periods between 4 and 24 h. After induction of apoptosis, cells were analyzed by the neutral comet assay to determine the percentage of apoptotic cells. To discover the duration of this protection, cells were grown in the EMF for 24 h and then removed for 24 to 48 h before heat shock and neutral comet assays were performed. Our results demonstrate that EMF exposure offers significant protection from apoptosis (P<.0001 for HL-60 and HL-60R, P<.005 for Raji) after 12 h of exposure and that protection can last up to 48 h after removal from the EMF. In this study we further demonstrate the effect of the EMF on DNA repair rates. DNA repair data were gathered by exposing the same cell lines to the EMF for 24 h before damaging the exposed cells and non-exposed cells with H2O2. Cells were allowed to repair for time periods between 0 and 15 min before analysis using the alkaline comet assay. Results showed that EMF exposure significantly decreased DNA repair rates in HL-60 and HL-60R cell lines (P<.001 and P<.01 respectively), but not in the Raji cell line. Importantly, our apoptosis results show that a minimal time exposure to an EMF is needed before observed effects. This may explain previous studies showing no change in apoptosis susceptibility and repair rates when treatments and EMF exposure were administered concurrently. More research is necessary, however, before data from this in vitro study can be applied to in vivo systems.

AI evidence extraction

Main findings

Exposure to a 0.15 mT, 60 Hz sinusoidal EMF significantly protected HL-60, HL-60R, and Raji cells from heat-induced apoptosis after 12 h of exposure, and this protection persisted up to 48 h after EMF removal. EMF exposure for 24 h significantly decreased DNA repair rates in HL-60 and HL-60R cells but not in Raji cells.

Outcomes measured

• Heat-induced apoptosis (percent apoptotic cells by neutral comet assay)
• DNA repair rates after H2O2 damage (alkaline comet assay)

Limitations

• In vitro study in cancer cell lines; authors note results may not apply to in vivo systems
• DNA repair effect not observed in all tested cell lines (no significant change in Raji)
• Sample size and replication details not provided in abstract

{
    "study_type": "in_vitro",
    "exposure": {
        "band": "ELF",
        "source": null,
        "frequency_mhz": 0.059999999999999997779553950749686919152736663818359375,
        "sar_wkg": null,
        "duration": "4–24 h exposure; protection assessed up to 48 h after removal; DNA repair assessed after 24 h exposure with 0–15 min repair intervals"
    },
    "population": "Human cancer cell lines (HL-60, HL-60R, Raji)",
    "sample_size": null,
    "outcomes": [
        "Heat-induced apoptosis (percent apoptotic cells by neutral comet assay)",
        "DNA repair rates after H2O2 damage (alkaline comet assay)"
    ],
    "main_findings": "Exposure to a 0.15 mT, 60 Hz sinusoidal EMF significantly protected HL-60, HL-60R, and Raji cells from heat-induced apoptosis after 12 h of exposure, and this protection persisted up to 48 h after EMF removal. EMF exposure for 24 h significantly decreased DNA repair rates in HL-60 and HL-60R cells but not in Raji cells.",
    "effect_direction": "mixed",
    "limitations": [
        "In vitro study in cancer cell lines; authors note results may not apply to in vivo systems",
        "DNA repair effect not observed in all tested cell lines (no significant change in Raji)",
        "Sample size and replication details not provided in abstract"
    ],
    "evidence_strength": "low",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "electromagnetic field",
        "ELF",
        "60 Hz",
        "0.15 mT",
        "apoptosis",
        "heat shock",
        "DNA repair",
        "comet assay",
        "HL-60",
        "Raji",
        "in vitro"
    ],
    "suggested_hubs": []
}

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