Medical/biological study (experimental study)

50 Hz extremely low frequency electromagnetic fields enhance protein carbonyl groups content in cancer cells: effects on proteasomal systems med./bio.

By: Eleuteri AM, Amici M, Bonfili L, Cecarini V, Cuccioloni M, Grimaldi S, Giuliani L, Angeletti M, Fioretti E

Published in: J Biomed Biotechnol 2009: 834239

Aim of study (acc. to author)

To study the influence of extremely low frequency electromagnetic fields on protein oxidation and on the 20S proteasome functionality (the complex responsible for the degradation of oxidized proteins). Furthermore, epigallocatechin-3-gallate (EGCG) protective action towards extremely low frequency electromagnetic fields mediated oxidative damage has been also evaluated.

Background/further details

Epigallocatechin-3-gallate is a natural compound (the major component of green tea) with antioxidant properties.
Cells were cultured in the presence and absence of EGCG and in the presence and absence of TPA.

Endpoint

cell function: proteasome functionality
oxidative stress (protein oxidation)

Exposure

- power transmission line

Exposure	Parameters
Exposure 1: 50 Hz Exposure duration: continuous for 24 hr to 72 hr	magnetic flux density: 1 mT effective value

Exposure 1

Main characteristics

Frequency	50 Hz
Type	magnetic field
Exposure duration	continuous for 24 hr to 72 hr

Exposure setup

Exposure source	solenoid
Setup	40 cm long solenoid with a diameter of 20 cm with 3 forward-backward-forward layers of 600 turns of 2 mm diameter copper wire inside a water-jacketed temperature and atmosphere regulated incubator; 11 cm x 17 cm exposure volume along the axis with a field variation of 5 %
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	1 mT	effective value	-	-	-

Exposed system:

intact cell/cell culture
Caco 2 cells (human colon adenocarcinoma cell line)

Methods Endpoint/measurement parameters/methodology

cell function: proteasome functionality (catalytic activities of different proteasome subunits (measurement of cleavage of short synthetic peptides); spectrofluorometry)
cell viability/cell division/proliferation: cell proliferation (cell counting); cell viability (MTT assay)
oxidative stress (protein oxidation; Western blot)

Investigated system:

intact cell/cell culture
cell lysates

Time of investigation:

during exposure
after exposure

Main outcome of study (acc. to author)

The exposure induced a time-dependent increase both in cell growth and in protein oxidation, more evident in the presence of TPA, while no changes in cell viability were detected. The results showed that the electromagnetic fields are able to affect the proteasome functionality inducing an increase in its proteolytic activity (particularly evident at 72 hours exposure and in the presence of TPA). The finding that epigallocatechin-3-gallate counteracts the electromagnetic fields related pro-oxidant effects demonstrate that this increase in proteasome activity is due to an increase in intracellular free radicals.

Study character:

medical/biological study
experimental study
full/main study
blind study

Study funded by

Istituto Superiore per la Prevenzione e la Sicurezza del Lavoro (ISPESL; National Institute for Occupational Safety and Prevention), Italy

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