title: Cyclooxygenase-2 inhibition suppresses alphavbeta6 integrin-dependent oral squamous carcinoma invasion.
abstract: Worldwide oral squamous cell carcinoma (OSCC) represents about 5.5% of all malignancies, with approximately 30,000 new cases each year in the United States. The integrin alpha(v)beta(6) and the enzyme cyclooxygenase-2 (COX-2) are implicated in OSCC progression and have been suggested as possible therapeutic targets. Each protein also is reported to identify dysplasias at high risk of malignant transformation, and current clinical trials are testing the efficacy of nonsteroidal anti-inflammatory drugs (NSAID) at preventing OSCC development. Given the probable increased expression of alpha(v)beta(6) and COX-2 in OSCC and the inhibition of several integrins by NSAIDs, we investigated whether NSAIDs affected alpha(v)beta(6)-dependent cell functions. We found that expression of both alpha(v)beta(6) and COX-2 was significantly higher in OSCC compared with oral epithelial dysplasias. Neither protein preferentially identified those dysplastic lesions that became malignant. Using OSCC cell lines, modified to express varying levels of alpha(v)beta(6), we assessed the effect of COX-2 inhibition on cell invasion. We found that the COX-2 inhibitor NS398 inhibited specifically alpha(v)beta(6)-dependent, but not alpha(v)beta(6)-independent, OSCC invasion in vitro and in vivo, and this effect was modulated through prostaglandin E(2) (PGE(2))-dependent activation of Rac-1. Transient expression of constitutively active Rac-1, or addition of the COX-2 metabolite PGE(2), prevented the anti-invasive effect of NS398. Conversely, RNA interference down-regulation of Rac-1 inhibited alpha(v)beta(6)-dependent invasion. These findings suggest that COX-2 and alpha(v)beta(6) interact in promoting OSCC invasion. This is a novel mechanism that, given the ubiquity of alpha(v)beta(6) expression by head and neck cancers, raises the possibility that NSAIDs could protect against OSCC invasion.
authors.affiliation: Tumour Biology Laboratory, Cancer Research UK Clinical Centre, Queen Mary's University, Charterhouse Square, London, United Kingdom.
authors.forename: Maria L
authors.initials: ML
authors.lastname: Nystrom
authors.forename: Diana
authors.initials: D
authors.lastname: McCulloch
authors.forename: Paul H
authors.initials: PH
authors.lastname: Weinreb
authors.forename: Shelia M
authors.initials: SM
authors.lastname: Violette
authors.forename: Paul M
authors.initials: PM
authors.lastname: Speight
authors.forename: John F
authors.initials: JF
authors.lastname: Marshall
authors.forename: Ian R
authors.initials: IR
authors.lastname: Hart
authors.forename: Gareth J
authors.initials: GJ
authors.lastname: Thomas
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D000951:Antigens, Neoplasm / Q000096:biosynthesis / Q000378:metabolism; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology*; D045744:Cell Line, Tumor; D051546:Cyclooxygenase 2 / Q000096:biosynthesis / Q000378:metabolism; D052246:Cyclooxygenase 2 Inhibitors / Q000494:pharmacology*; D015232:Dinoprostone / Q000378:metabolism / Q000494:pharmacology; D004847:Epithelial Cells / Q000473:pathology; D006801:Humans; D016023:Integrins / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D009062:Mouth Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology*; D009361:Neoplasm Invasiveness; D009578:Nitrobenzenes / Q000494:pharmacology; D011485:Protein Binding; D013449:Sulfonamides / Q000494:pharmacology; D023041:Xenograft Model Antitumor Assays; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D000951:Antigens, Neoplasm; D052246:Cyclooxygenase 2 Inhibitors; D016023:Integrins; D009578:Nitrobenzenes; C107953:RAC1 protein, human; D013449:Sulfonamides; C073878:integrin alphavbeta6; C080955:N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide; D051546:Cyclooxygenase 2; D020830:rac1 GTP-Binding Protein; D015232:Dinoprostone