Induction of apoptosis and up-regulation of cellular proliferation in oral leukoplakia cell lines inside electric field.
OBJECTIVE
In dentistry, metallic alloys are used for dentures, restorative materials, and orthodontic devices. Electric voltages up to 950 mV may occur between different dental alloys in the oral cavity. This study aimed to investigate physiologic reactions of oral leukoplakia cells in vitro to electric fields.


METHODS
A human leukoplakia cell line (MSK-LEUK1), cultivated in keratinocyte growth medium (KGM-2) supplemented with growth factors in 5% CO(2) humidified air at 37°C, was exposed to electric field strength of 1-20 V/m for 24 hours in a custom-made pulse chamber. The cells were then analyzed for proliferation with the use of BrdU assay and for apoptosis with the use of TUNEL assay. Findings were assessed with the use of fluorescent microscopy. Ultrastructural changes were studied by transmission electron microscopy.


RESULTS
Electric field strength of 1-10 V/m led to up-regulation of cell proliferation rate from 10.64% to 44.06% (P = .0001). The apoptotic index increased significantly (P = .0001) from 20.03% at 1 V/m to 46.56% at 10 V/m. Individual cell keratinization was seen in leukoplakia cells treated with 16 V/m.


CONCLUSIONS
Oral galvanism induces subcellular changes in oral precancer cells in vitro that closely simulate some of the morphologic features of oral squamous cell carcinoma cells in vivo.
Department of Prosthetic Dentistry, Dental School, University of Cologne, Germany.
Ahmed
A
Korraah
Margarete
M
Odenthal
Marion
M
Kopp
Nadarajah
N
Vigneswaran
Peter G
PG
Sacks
Hans Peter
HP
Dienes
Hartmut
H
Stützer
Wilhelm
W
Niedermeier
D017209:Apoptosis / Q000528:radiation effects*; D018929:Cell Culture Techniques; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000528:radiation effects; D016009:Chi-Square Distribution; D004570:Electrogalvanism, Intraoral; D004574:Electromagnetic Fields; D004847:Epithelial Cells / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D020287:In Situ Nick-End Labeling; D007972:Leukoplakia, Oral / Q000473:pathology*; D008875:Middle Aged; D011859:Radiography; D015854:Up-Regulation