[A preliminary study on role of acid sphingomyelinase in receptor clustering induced by 50-Hz magnetic fields].

Abstract

OBJECTIVE: To investigate the relationship among a 50-Hz MF-induced epidermal growth factor receptor (EGFR) clustering, acid sphingomyelinase (A-SMase) and ceramide (CER), and to explore the possible mechanism of receptor clustering. METHODS: Human amnion (FL) cells were exposed to a 50-Hz sinusoidal magnetic field at 0.4 mT for 15 min with or without imipramine, a specific inhibitor of A-SMase and ceramide pretreatment. EGF treatment served as the positive control and DMSO treatment served as the solvent control. The EGFR was labeled with polyclonal anti-EGFR antibody and the clustering of EGFR was analyzed using immunofluorescence and confocal microscopy. The percentage of cells with EGFR clustering was counted and compared. RESULTS: Both EGF treatment and 50-Hz MF exposure could induce EGFR clustering. However, the effect could be eliminated by imipramine pretreatment for 4 hours. When FL cells were incubated with ceramide following the imipramine pretreatment for 30 min, EGFR clustering induced by 50-Hz MF exposure could be recovered. CONCLUSION: EGFR clustering induced by 50-Hz MF depends on A-SMase activity, and ceramide, as the hydrolyzate from A-SMase might participate in the process of EGFR clustering.

AI evidence extraction

Main findings

In human amnion (FL) cells, both EGF treatment and 50-Hz magnetic field exposure (0.4 mT, 15 min) induced EGFR clustering. Imipramine pretreatment (A-SMase inhibitor) eliminated the magnetic-field-induced clustering, and subsequent ceramide incubation after imipramine restored clustering induced by magnetic field exposure.

Outcomes measured

• EGFR clustering (immunofluorescence/confocal microscopy; % cells with clustering)
• Role of acid sphingomyelinase (A-SMase) activity in EGFR clustering
• Effect of ceramide on EGFR clustering after A-SMase inhibition

Limitations

• In vitro cell study; findings may not generalize to humans
• Sample size not reported in abstract
• Short exposure duration (15 min)
• Outcome is a cellular signaling/structural endpoint (EGFR clustering), not a clinical health outcome

Suggested hubs

• occupational-exposure (0.35)
  Published in an industrial hygiene/occupational diseases journal and involves 50-Hz magnetic field exposure relevant to workplace ELF MF contexts.

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    "exposure": {
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        "source": null,
        "frequency_mhz": 0.05000000000000000277555756156289135105907917022705078125,
        "sar_wkg": null,
        "duration": "15 min"
    },
    "population": null,
    "sample_size": null,
    "outcomes": [
        "EGFR clustering (immunofluorescence/confocal microscopy; % cells with clustering)",
        "Role of acid sphingomyelinase (A-SMase) activity in EGFR clustering",
        "Effect of ceramide on EGFR clustering after A-SMase inhibition"
    ],
    "main_findings": "In human amnion (FL) cells, both EGF treatment and 50-Hz magnetic field exposure (0.4 mT, 15 min) induced EGFR clustering. Imipramine pretreatment (A-SMase inhibitor) eliminated the magnetic-field-induced clustering, and subsequent ceramide incubation after imipramine restored clustering induced by magnetic field exposure.",
    "effect_direction": "harm",
    "limitations": [
        "In vitro cell study; findings may not generalize to humans",
        "Sample size not reported in abstract",
        "Short exposure duration (15 min)",
        "Outcome is a cellular signaling/structural endpoint (EGFR clustering), not a clinical health outcome"
    ],
    "evidence_strength": "low",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "50-Hz magnetic field",
        "ELF MF",
        "0.4 mT",
        "EGFR clustering",
        "acid sphingomyelinase",
        "ceramide",
        "imipramine",
        "FL cells",
        "confocal microscopy"
    ],
    "suggested_hubs": [
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            "weight": 0.34999999999999997779553950749686919152736663818359375,
            "reason": "Published in an industrial hygiene/occupational diseases journal and involves 50-Hz magnetic field exposure relevant to workplace ELF MF contexts."
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    ]
}

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