In previous studies (see publication 1254, publication 5621) a decrease in efficacy of the selective estrogen receptor modulator tamoxifen was observed in breast cancer cells exposed to electromagnetic fields. Tamoxifen is applied in estrogen receptor positive breast cancer therapy as it binds to estrogen receptors of breast cancer cells and through this prevents their proliferation. As estrogen receptors can be modified by cofactors, gene expression of these cofactors (coactivator: AIB1, SRC-1, corepressor: N-Cor, SMRT) should be elucidated. It is reported that in tumors which express higher amounts of coactivators and less corepressors tamoxifen induces proliferation of the breast cancer cells and significantly reduces the disease-free survival.
Exposure duration: continuous for 24 h up to 96 h
|Setup||75 cm long copper tube with a diameter of 30 cm, closed at both ends by a copper plate, copper wire wound round the tube and connected to a signal generator, for stabilization of magnetic field small sensor coil in the center of the tube|
|Sham exposure||A sham exposure was conducted.|
|magnetic flux density||1.2 µT||-||-||-||-|
The gene expression of both coactivators were more strongly expressed in the exposed breast cancer cells while the gene expression of the two corepressors decreased. The RNA analysis was confirmed by protein analysis.
The observed increased estrogen receptor coactivators expression and decreased estrogen receptor corepressors can explain the decrease in efficacy of tamoxifen during exposure to electromagnetic fields.