RESUMEN
Background and purpose: There have been no reports on the clinical and biological significance of the co-expression of inducible nitric oxide synthase (iNOS) and β-catenin (β-cat) in has.pharyngeal carcinoma(NPC). This study was aimed to investigate the expression of iNOS and β-cat in NPC, to analyze their interrelation, and to explore their roles in the carcinogenesis, development, invasion, and metastasis of NPC. Methods: The expression of iNOS and β-cat was examined in 50 poorly differentiated NPC and 15 normal nasopharyngeal epithelium tissue by immunohistochemical staining (SP method). None of the patients had received radiotherapy and chemotherapy. The results of immunostaining were observed by two pathologists independently, using double blind scoring method. iNOS and β-cat expression were categorized by the extent and intensity of staining using a semiquantitative method. Results: No iNOS expression was observed in 15 normal nasopharyngeal epithelium, but β-cat expression was located in cytomembrane in normal samples. The positive rate of iNOS protein expression was 74.0% (37/50) in NPC tissues. The expression of iNOS was statistically different among the NPC group and normal nasopharyngeal epithelium group, T_(1-2) group and T_(3-4) group, metastatic lymph nodes group and no metastatic lymph nodes group. There was a great quantity of β-cat expression in cytoplasm, little or no β-cat expression in cytomembrane and nucleus in NPC tumorous tissues. Statistical analysis indicated that strong positive expression of β-cat in cytoplasm was significantly higher in NPC than those of normal nasopharyngeal epithelium. The positive expression of β-cat was significantly correlated with clinical stage, invasion and lymph gland metastasis. Neither iNOS nor β-cat was significantly different between different ages and genders. There was a positive relationship between iNOS and β-cat expression in NPC tissues (r=0.394, P=0.005). Conclusion: The positive expressions of iNOS and β-cat in cytoplasm were significantly correlated with clinical stage, invasion and metastasis, and were not significantly different in terms of ages and genders of the patients. There was a positive relationship between the expression of iNOS and β-cat in NPC tissues. Co-overexpression of iNOS and β-cat may play an important role in carcinogenesis, development, invasion, and metastasis of NPC.