title: Down-regulation of nitric oxide synthase-2 and cyclooxygenase-2 pathways by p53 in squamous cell carcinoma.
abstract: The goal of this study was to analyze the correlation between inducible nitric oxide synthase (iNOS) and COX-2 activities and p53 gene status in head and neck squamous cell carcinomas (HNSCCs) in vivo and in vitro. In a series of 43 HNSCCs we observed an up-regulation of both iNOS and COX-2 pathways in tumor tissues and both activities were correlated each other (rs = 0.612 and P = 0.0002). We also found that p53-mutated HNSCCs (25 cases, 58.1%) showed higher levels of iNOS activity and cGMP in comparison with wild-type p53 tumors (18 cases, 41.9%) (P = 0.0005 and P = 0.01), as well as higher iNOS immunohistochemical expression (P = 0.03). Analogously, higher PgE2 levels were documented in p53-mutated HNSCCs when compared with wild-type p53 tumors (P = 0.015) and COX-2 protein expression was higher in p53-mutated HNSCCs (P = 0.007). A431 cancer cells expressing a p53 temperature-sensitive mutant showed an approximately 1.9- and 2.6-fold decrease in spontaneous NO(2-)/NO(3-) and PgE2 synthesis at permissive temperature, respectively, when compared with the same cells at nonpermissive temperature (P <or= 0.001). Basal levels of iNOS and COX-2 proteins and mRNAs were markedly suppressed by restoration of p53 activity. Our results indicate that p53 gene mutation(s) may be responsible for iNOS and COX-2 up-regulation frequently observed in HNSCCs and suggest that restoration of wild-type p53 expression may interfere with tumor growth by inhibiting iNOS and COX-2 pathways.
authors.affiliation: Department of Oto-Neuro-Ophthalmologic Surgery, University of Florence, Florence, Italy.
authors.forename: Oreste
authors.initials: O
authors.lastname: Gallo
authors.forename: Nicola
authors.initials: N
authors.lastname: Schiavone
authors.forename: Laura
authors.initials: L
authors.lastname: Papucci
authors.forename: Iacopo
authors.initials: I
authors.lastname: Sardi
authors.forename: Lucia
authors.initials: L
authors.lastname: Magnelli
authors.forename: Alessandro
authors.initials: A
authors.lastname: Franchi
authors.forename: Emanuela
authors.initials: E
authors.lastname: Masini
authors.forename: Sergio
authors.initials: S
authors.lastname: Capaccioli
mesh_terms: D000328:Adult; D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000378:metabolism* / Q000473:pathology; D051546:Cyclooxygenase 2; D015536:Down-Regulation; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006258:Head and Neck Neoplasms / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins; D008875:Middle Aged; D009566:Nitrates / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II; D009573:Nitrites / Q000378:metabolism; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D011453:Prostaglandins / Q000096:biosynthesis; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*
chemical_list: D007527:Isoenzymes; D008565:Membrane Proteins; D009566:Nitrates; D009573:Nitrites; D011453:Prostaglandins; D016159:Tumor Suppressor Protein p53; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases