Study type: Medical/biological study (experimental study)

Induction of tamoxifen resistance in breast cancer cells by ELF electromagnetic fields. med./bio.

Published in: Biochem Biophys Res Commun 2005; 336 (4): 1144-1149

Aim of study (acc. to author)

To study whether low frequency electromagnetic field exposure interferes with the anti-estrogenic activity of tamoxifen.

Background/further details

Two different clones of the breast cancer cell line MCF-7 were exposed to highly homogeneous 50 Hz electromagnetic fields and IC50 (inhibitory concentration 50 %) values were calculated from dose-response curves of tamoxifen at various field intensities.
Tamoxifen has been used for treatment of estrogen receptor positive breast cancer for nearly 30 years. While most patients with advanced estrogen-responsive breast cancer initially profit from tamoxifen treatment, most of their tumor recur and respond no longer to the treatment.
Tamoxifen solutions at increasing final concentrations of 10-8 - 5 x 10-6 M were used.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: continuous for 7 days
Exposure 2: 50 Hz
Exposure duration: continuous for 7 days
Exposure 3: 50 Hz
Exposure duration: continuous for 7 days
Exposure 4: 50 Hz
Exposure duration: continuous for 7 days

Exposure 1

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration continuous for 7 days
Exposure setup
Exposure source
Chamber Incubator maintained at 37°C with CO2 concentration kept at 5%.
Setup The coils were dimensioned in such a manner that the induced magnetic field was homogeneous in the center space of the incubator where the cells were kept. Exactly the same time duration and set-up conditions were used for sham exposure but in the absence of magnetic field.
Additional info For heating, a bifilar copper coil was supplied with an anti parallel current so that the net applied static field of the heating coil was nulled.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 100 µT - measured - -

Exposure 2

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration continuous for 7 days
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 10 µT - measured - -

Exposure 3

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration continuous for 7 days
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1.2 µT - measured - -

Exposure 4

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration continuous for 7 days
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 200 nT - measured - -

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

A field intensity-dependent shift of tamoxifen dose-response curves to higher concentrations with a maximal response at 1.2 µT was revealed. Hypothetically, electromagnetic field exposure could contribute to tamoxifen resistance found in breast cancer after long-term treatment.

Study character:

Study funded by

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