Medical/biological study (experimental study)

Direct current electrical fields induce apoptosis in oral mucosa cancer cells by NADPH oxidase-derived reactive oxygen species med./bio.

By: Wartenberg M, Wirtz N, Grob A, Niedermeier W, Hescheler J, Peters SC, Sauer H

Published in: Bioelectromagnetics 2008; 29 (1): 47-54

Aim of study (acc. to author)

This study was performed to investigate the effects of electrical fields on apoptosis of oral mucosa cancer cells in vitro.

Background/further details

As the presence of more than one dental alloy in the oral cavity often causes direct currents and voltage the cellular apoptosis mechanisms on oral mucosa cancer cells exposed to electric fields should be investigated. Oxidation-reduction using amongst others free radical scavengers were characterized in particular.

Endpoint

cell viability/cell division/proliferation: cell proliferation

Exposure

- 0 Hz
- DC
- signals/pulses
- electric current application

Exposure	Parameters
Exposure 1: DC/static Modulation type: pulsed Exposure duration: continuous for 24 h	electric field strength: 2 V/m minimum electric field strength: 16 V/m maximum

Exposure 1

Main characteristics

Frequency	DC/static
Type	electric current
Waveform	pulsed
Exposure duration	continuous for 24 h

Modulation

Modulation type	pulsed
Pulse width	900 ms

Exposure setup

Exposure source	conductive coupling electrode
Setup	14 silver electrodes with a distance of 5 cm placed into the culture medium at the border of the petri dish; for each pulse a different electrode pair was used to generate a rotating field
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
electric field strength	2 V/m	minimum	-	-	-
electric field strength	16 V/m	maximum	-	-	-

Exposed system:

intact cell/cell culture
UM-SCC-14C (human oral mucosa cancer cell line)

Methods Endpoint/measurement parameters/methodology

cell function: intracellular reactive oxygen species, dichlorofluorescein fluorescence; intracellular glutathione content, 5-chloromethylfluorescein diacetate (5-CMF-DA) fluorescence
cell viability/cell division/proliferation: cell proliferation (Ki67 immunohistochemistry); cell lethality (Sytox green-positive cell nuclei mark dead cells, fluorescence microscopy)

Investigated system:

intact cell/cell culture

Investigated organ system:

oral cavity

Time of investigation:

after exposure

Main outcome of study (acc. to author)

The electrical fields exposure to oral mucosa cancer cells, dose-dependently resulted in decreased cell proliferation, increased cell cycle arrest, and increased apoptosis. Furthermore, robust reactive oxygen species generation, increased expression of NADPH oxidase subunits as well as heat shock protein 70 was observed.
These results and the observation with free radical scavengers suggest that apoptosis in oral mucosa cancer cells is initated by reactive oxidative species generation in response to direct current electrical field exposure.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

not stated/no funding

Lantow M et al. (2006): ROS release and Hsp70 expression after exposure to 1,800 MHz radiofrequency electromagnetic fields in primary human monocytes and lymphocytes
Lupke M et al. (2004): Cell activating capacity of 50 Hz magnetic fields to release reactive oxygen intermediates in human umbilical cord blood-derived monocytes and in Mono Mac 6 cells
Rollwitz J et al. (2004): Fifty-hertz magnetic fields induce free radical formation in mouse bone marrow-derived promonocytes and macrophages
Wartenberg M et al. (1997): Electrical fields enhance growth of cancer spheroids by reactive oxygen species and intracellular Ca2+