[ELF-MFはBcl-2ファミリータンパク質の発現調節によりK562細胞のケルセチン誘導アポトーシスを減少させる] med./bio.

To examine the effects of exposure to an extremely low frequency magnetic field on the apoptosis induced by four different compounds (vinblastine, etoposide, quercetin, resveratrol) in human K562 leukemia cells.

In the first experiment, the effects of 1 µM vinblastine, 1 µM etoposide (used as an anti-cancer drug) and 25 µM resveratrol (a stilbenoid, potential positive health effects are discussed) either alone or in combination with an extremely low frequency magnetic field on the growth and cell viability were examined.
In the second experiment, the effects of 25 µM quercetin (a flavonoid, has been suggested as an anti-cancer drug) either alone or in combination with an extremely low frequency magnetic field on the growth, cell viability, generation of reactive oxygen species, protein expression, enzyme activity of the caspase-3, apoptosis rate and cell cycle were examined.
In the third experiment, cells were exposed to different magnetic flux densities alone or in combination with quercetin and the number of apoptotic cells was determined.
Positive controls were performed.

• 無傷細胞／細胞培養
• K562 cells (human erythroleukemic cell line)

In the first experiment, no significant differences were observed in the cell proliferation and cell viability between the exposed and the sham exposed cells. Vinblastine, etoposide, and resveratrol had an anti-proliferative effect on the cells. However, this effect was not influenced by the magnetic field exposure.
The second experiment showed that quercetin had an anti-proliferative effect, but this effect was attenuated by the magnetic field exposure: In cell cultures cultivated in the presence of quercetin and exposed for 48 and 72 hours, the cell viability was significantly increased and the number of apoptotic cells (also after 24 hours and as experiment 3 showed also at magnetic flux densities of 0.01 mT and 0.1 mT, but not at 2 mT) as well as the enzyme activity of the caspase-3 were significantly decreased compared to sham exposed cell cultures with quercetin. Additionally, in 48 hours-exposed cells with quercetin the numbers of cells in the G1 phase and the S phase were significantly increased and the number of cells in the G2 phase/mitosis significantly decreased compared to sham exposed cells with quercetin. The simultaneous treatment with magnetic field exposure for 24 hours and quercetin significantly increased the protein expression of Bcl-2 in comparison to the other groups and prevented the quercetin-induced significant down-regulation of Mcl-1 and Bcl-xL. After 48 hours of exposure, the protein expression of Hsp70 was significantly increased when compared to the control group, while after 72 hours it was significantly increased when simultaneously treated with exposure and quercetin. No significant changes occurred regarding the level of the reactive oxygen species.
The results indicate that extremely low frequency magnetic fields could be able to render K562 cells resistant to quercetin-induced apoptosis. Hence, these magnetic fields may have negative implications for anti-tumor therapies.