Transfection and ligation of CD40 in human oral keratinocytes affect proliferation, adhesion and migration but not apoptosis in vitro.
OBJECTIVE
CD40 expression is restricted to Keratinocytes of normal epidermis or stratified squamous epithelium of oral mucosa. Ligation of CD40 inhibits keratinocyte proliferation and apoptosis. The aim of this study was to investigate the functional significance of CD40 in the proliferation, apoptosis, adhesion and migration of human oral keratinocytes in vitro.


METHODS
The CD40-negative oral keratinocyte line OSC19, its CD40-positive transfected derivative (OSC19T-CD40) and null transfectants (OSC19T-control), with and without stimulation by soluble protein CD40 ligand (sCD40L) or anti-CD40 antibodies were used.


RESULTS
OSC19T-CD40 showed significantly (P < 0.001) slower growth than the null transfectants and parent cells. OSC19T-CD40 proliferation was inhibited by ligation with sCD40L and blocking by two anti-CD40 antibodies, but stimulated by a third. Binding of CD40 with ligand or antibody had no effect on keratinocyte apoptosis in any cell line. The capacity of OSC19T-CD40 cells to adhere to CD40L-coated wells was significantly greater (P < 0.001) than that of parent OSC19 and OSC19T-control cells, and the migration rate of OSC19T-CD40 cells was significantly higher than parent OSC19 (P = 0.038 on fibronectin, P = 0.004 on Matrigel) or OSC19T-control (P =0.017 on fibronectin, P = 0.013 on Matrigel) cells.


CONCLUSIONS
CD40 is an important molecule in keratinocyte homeostasis, and has more than one ligand. The ligand that is bound may be critical in oral epithelial homeostasis, the development of malignancy and the behaviour of the subsequent tumour.
Villarroel Dorrego
M
M
Oral and Maxillofacial Pathology Unit, Eastman Dental Institute for Oral Healthcare Sciences, University College London, London, UK.
Whawell
S A
SA
Speight
P M
PM
Barrett
A W
AW
D017209:Apoptosis / Q000187:drug effects; D019013:CD40 Antigens / Q000096:biosynthesis / Q000494:pharmacology*; D023201:CD40 Ligand / Q000378:metabolism; D002448:Cell Adhesion; D002465:Cell Movement; D049109:Cell Proliferation / Q000187:drug effects; D004817:Epidermis / Q000187:drug effects / Q000378:metabolism; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D015603:Keratinocytes / Q000187:drug effects* / Q000378:metabolism*; D009061:Mouth Mucosa / Q000187:drug effects* / Q000378:metabolism*
D019013:CD40 Antigens; D023201:CD40 Ligand