Study type: Medical/biological study (experimental study)

ELF-MF attenuates quercetin-induced apoptosis in K562 cells through modulating the expression of Bcl-2 family proteins. med./bio.

Published in: Mol Cell Biochem 2014; 397 (1-2): 33-43

Aim of study (acc. to author)

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.

Background/further details

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.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: continuous for 24, 48 or 72 hours
experiment 1 + 2
Exposure 2: 50 Hz
Exposure duration: continuous for 24, 48 or 72 hours
experiment 3

Exposure 1

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration continuous for 24, 48 or 72 hours
Additional info experiment 1 + 2
Exposure setup
Exposure source
Chamber cells were exposed in petri dishes or multiwell plate
Setup exposure system consisted of two identical apparatuses, each containing a waveform generator, a current amplifier, and a pair of Helmholtz coils; pair of Helmholtz coils had a mean radius of 13.0 ± 0.5 cm; in each coil, the number of turns was 800 with a 2 mm² wire giving a resulting resistance of 2.4 ohm and an inductance of 39 ± 1 mH; mean vertical distance between the coils was 13.5 ± 0.5 cm; current could either flow in the same direction (exposure) or in the opposite direction (sham system), where the magnetic flux density is "theoretically zero"; each coil was placed within two separate incubators (one for exposure, one for sham exposure) at a temperature of 37°C and an atmosphere of 95% air/5% CO2and 100% relative humidity.
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1 mT - measured - -

Exposure 2

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration continuous for 24, 48 or 72 hours
Additional info experiment 3
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 0.01 mT - measured - -
magnetic flux density 0.1 mT - measured - -
magnetic flux density 2 mT - measured - -

Reference articles

  • Iorio R et al. (2013): ELF-MF transiently increases skeletal myoblast migration: possible role of calpain system.
  • Kirschvink JL (1992): Uniform magnetic fields and double-wrapped coil systems: improved techniques for the design of bioelectromagnetic experiments.

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

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.

Study character:

Study funded by

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