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P. Ferreira, A. Figueiredo, G. Lima; Increased Expression of Inducible Nitric Oxide Synthase for Dysplasia, Carcinoma in situ and Squamous Cell Carcinoma of the Conjunctiva: Immunohistochemical Study . Invest. Ophthalmol. Vis. Sci. 2005;46(13):3373.
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Purpose: Recently, most of studies have indicated that nitric oxide (NO) plays an important role in carcinogenesis and tumor progression. Inducible nitric oxide synthase(iNOS) has been found at significantly higher expression levels in head and neck squamous cell carcinoma (HNSCCA) specimens as compared with that in normal tissue. Furthermore, these data provided strong evidence for the role of iNOS generating NO in HNSCCA progression. However, there was no report about whether expression of iNOS in conjunctival carcinoma is associated with its biological behavior. This study was designed to investigate the correlation between expression of inducible nitric oxide synthase mRNA (iNOS mRNA) in squamous cell carcinoma of tongue tissue and its invasive growth, neck lymph node metastasis, and prognosis. The inducible nitric oxide synthase (iNOS) is involved primarily in inflammatory and carcinogenesis processes. The expression of iNOS in squamous cell carcinoma of the conjunctiva has not yet been demonstrated. Methods: Thirty standard paraffin sections wich 10 had diagnosis of conjunctival dysplasia, 10 carcinoma in situ and 10 squamous cell carcinoma. All cases were prepared and blocked for endogenous peroxidase and avidin/biotin, placed in citrate buffer, and stained for iNOS. Cases were divided into 2 groups according to iNOS tumor cell expression: negative or positive if at least 20 cells displayed distinct immunostaining. Results: Inducible NOS protein (16 of 25, 64%) activity was detected for conjunctival dysplasia (1 of 10, 10%), carcinoma in situ (5 of 10, 50%) and squamous cell carcinoma (7 of 10, 70%) Conclusions: We have demonstrated an enhanced expression of iNOS protein in a number of carcinoma in situ and squamous cell carcinoma compared with dysplasia. Such observation suggests that the iNOS protein may play a role during malignant transformation on conjunctival tissues. Further studies will be necessary in order to elucidate the mechanisms involved in this process.
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