Journal Article

Magnetic fields (MF) of 50 Hz at 1.2 μT as well as 100 μT cause uncoupling of inhibitory pathways of adenylyl cyclase mediated by melatonin 1a receptor in MF-sensitive MCF-7 cells

Masami Ishido, Hiroshi Nitta and Michinori Kabuto

in Carcinogenesis

Volume 22, issue 7, pages 1043-1048
Published in print July 2001 | ISSN: 0143-3334
Published online July 2001 | e-ISSN: 1460-2180 | DOI: http://dx.doi.org/10.1093/carcin/22.7.1043
Magnetic fields (MF) of 50 Hz at 1.2 μT as well as 100 μT cause uncoupling of inhibitory pathways of adenylyl cyclase mediated by melatonin 1a receptor in MF-sensitive MCF-7 cells

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Magnetic fields (MF) of 60 Hz at 1.2 μT were previously shown to inhibit the antiproliferative effect of melatonin on MCF-7 cells (Liburdy,R.P., 1993, J. Pimeal Res. 14, 89–97). In addition, three laboratories (Blackman,C.F. and Benane,S.G., 1998; Luben,R.A. and Morgan,A.P., 1998; Morris,J.E., Chrisler,W.B., Miller,D.L., Sasser,L.B. and Anderson,L.E., 1998; 20th Annual Meeting of the Bioelectromagnetics Society, At. Pete Beach, FL) independently reported results consistent with this finding. In this study, we investigated the molecular basis of the biological effects of MF using MCF-7 cells. Only 1a melatonin receptors were identified by the [125I]melatonin binding assay and RT–PCR analysis. Moreover, preceding exposures to MF of 100 μT for 3, 5 and 7 days blocked the melatonin-induced inhibition of cAMP accumulation in a time-dependent manner, while none of the melatonin receptor functions or GTPase and adenylyl cyclase activities were affected. Estrogen-evoked cell proliferation was not altered by MF either. Exposure to 1.2 μT MF exerted the same effects on the melatonin-signaling pathway as that to 100 μT. Thus, this is the first study to provide evidence that MF may cause uncoupling of signal transduction from melatonin receptors to adenylyl cyclase.

Keywords: ABTS, 2,2′-azino-di-(3-ethylbenzthiazolinesulfonate); ATCC, American Type Culture Collection; BrdU, bromodeoxyuridine; ELISA, enzyme-linked immunosorbent assay; ERα, estrogen receptor α; IBMX, 3-isobutyl-1-methylxanthine; LH/FSH, luteinizing hormone/follicle stimulating hormone; MF, magnetic fields; NAT, N-acetyltransferase; RT–PCR, reverse transcriptase–polymerase chain reaction.

Journal Article.  6006 words.  Illustrated.

Subjects: Clinical Cytogenetics and Molecular Genetics

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