Cyclooxygenase-2 is a possible target of treatment approach in conjunction with photodynamic therapy for various disorders in skin and oral cavity.
BACKGROUND
Anti-cancer effects of cyclooxygenase (COX)-2 inhibitors have been reported, but not fully investigated in skin and oral diseases. 5-aminolaevulinic acid (ALA)-based photodynamic therapy (PDT) for treating those patients with skin and oral lesions is a highly sophisticated procedure, but the incidence of disease recurrence after treatment is rather significant.


OBJECTIVE
To confirm that COX-2 could be a molecular target in adjunctive therapy to ALA-based PDT, we investigated (i) COX-2 expression in various skin and oral diseases, and (ii) the inhibitory effects on cellular growth of COX-2 selective inhibitor (nimesulide), ALA-based PDT and their combination on human oral squamous cell carcinoma (SCC) cell lines.


METHODS
A total of 129 biopsy samples from the skin and oral mucosal lesions were tested immunohistochemically for COX-2 expression. Then the in vitro effects of nimesulide, ALA-based PDT, and their combination were determined on two SCC cell lines, HSC-2 and HSC-4. Three different methods (MTT assay, double-staining for annexin V and propidium iodide, caspase-3/CPP32 fluorometric protease assay) were applied for evaluation of their inhibitory effects on these two cell lines.


RESULTS
Among the skin diseases, a considerable number of COX-2 high expressers were found in actinic keratosis (15 of 25, 60%), Bowen's disease (13 of 17, 76%) and extramammary Paget's disease (15 of 15, 100%). In contrast, only one of 33 (3%) basal cell carcinoma tumours was a COX-2 high expresser. Among the oral mucosal biopsies, the proportion of COX-2 high expressers increased gradually from hyperplasia (one of six, 17%) through mild dysplasia (five of eight, 63%) and moderate dysplasia (20 of 23, 87%) to severe dysplasia (two of two, 100%). Nimesulide had an inhibitory effect in vitro on HSC-2 (proven to be a COX-2 high expresser), but not on HSC-4 (a COX-2 non-expresser). While ALA-based PDT showed an inhibitory effect on both HSC-2 and HSC-4, most importantly the combination of nimesulide and ALA-based PDT demonstrated a significant synergistic effect on the cellular growth inhibition of only HSC-2, but not of HSC-4.


CONCLUSIONS
Our study strongly suggests that COX-2 can be one of the molecular targets in treating various skin and oral diseases. The results from our in vitro experiments also prompt us to develop a new protocol with a combination of COX-2 selective inhibitor and ALA-based PDT for more effective treatment of those diseases.
Akita
Y
Y
Department of Pathology, Aichi Medical University School of Medicine, Nagakute, Aichi 480-1195, Japan.
Kozaki
K
K
Nakagawa
A
A
Saito
T
T
Ito
S
S
Tamada
Y
Y
Fujiwara
S
S
Nishikawa
N
N
Uchida
K
K
Yoshikawa
K
K
Noguchi
T
T
Miyaishi
O
O
Shimozato
K
K
Saga
S
S
Matsumoto
Y
Y
D000622:Aminolevulinic Acid / Q000627:therapeutic use; D001913:Bowen's Disease / Q000188:drug therapy / Q000201:enzymology; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy / Q000201:enzymology; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000627:therapeutic use*; D004357:Drug Synergism; D004359:Drug Therapy, Combination; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D007527:Isoenzymes / Q000032:analysis / Q000037:antagonists & inhibitors*; D007642:Keratosis / Q000188:drug therapy / Q000201:enzymology; D008565:Membrane Proteins; D009059:Mouth Diseases / Q000188:drug therapy* / Q000201:enzymology; D009061:Mouth Mucosa / Q000201:enzymology; D009062:Mouth Neoplasms / Q000188:drug therapy / Q000201:enzymology; D010145:Paget Disease, Extramammary / Q000188:drug therapy / Q000201:enzymology; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000627:therapeutic use; D011451:Prostaglandin-Endoperoxide Synthases / Q000032:analysis; D012871:Skin Diseases / Q000188:drug therapy* / Q000201:enzymology; D013449:Sulfonamides / Q000627:therapeutic use*
D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D007527:Isoenzymes; D008565:Membrane Proteins; D017319:Photosensitizing Agents; D013449:Sulfonamides; D000622:Aminolevulinic Acid; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; C012655:nimesulide