Expression of inducible nitric oxide synthase in nasopharyngeal carcinoma(NPC) and its significance / 中国癌症杂志

ABSTRACT

Background and purpose:Inducible nitric oxide synthase(iNOS) overexpression has been detected in various malignancies.Nitric oxide(NO) produced by iNOS play an important role in the carcinogenesis,growth,invasion,metastasis and angiogenesis of tumors.However,the clinical and biological significance of the expression of iNOS in NPC were rarely reported in the literature.This study was to investigate the expression of iNOS in NPC and its role in the carcinogenesis,development,invasion and metastasis of NPC.Methods:The expression of iNOS was examined in 40 poorly differentiated NPC and 10 normal nasopharyngeal epithelium tissues by immunohistochemical staining(SP method).The results of immunoassaying were observed by two pathologists independently,using double blank scoring method.iNOS expression was categorized on the base of extent and intensity of staining using a semi quantitative method.The immunoreactive score was obtained by multiplying the extent score with the intensity of score.An immunoreactive score of 2 or higher was considered positive expression.Results:① iNOS was expressed in both the nucleus and cytoplasm of the tumor tissues.The intensity of iNOS expression was stronger in the nucleus than in the cytoplasm of the tumor tissues.②iNOS expression were significantly higher in NPC than those of normal nasopharyngeal epithelium.The positive protein expression rates of iNOS were 67.5%(27/40).The positive expressions of iNOS were significantly correlated with clinical stage,invasion and metastasis. There were no significant difference in terms of age and gender.Conclusions:① Immunohistochemical examination revealed that iNOS expression in the NPC tissues was located in both the nucleus and cytoplasm of the tumorous tissues.The intensity of iNOS expression was stronger in the nucleus than in the cytoplasm of the tumorous tissues.②iNOS may play an important role in the carcinogenesis,development,invasion,metastasis of NPC,respectively.The radiotherapeutic response of NPC may be enhanced by using the selective inhibitors of iNOS.