Abstract
AIMS: Prolonged production of the free radical, nitric oxide (NO) by the enzyme inducible nitric oxide synthase (iNOS) plays an important role in tumour progression by promoting angiogenesis, invasion and inducing mutation in tumour suppressor gene. The purpose of this study is to evaluate the expression and intensity of iNOS in normal oral mucosa, precancer and oral squamous cell carcinoma (OSCC). MATERIALS AND METHODS: An immunohistochemical study was performed using rabbit monoclonal antibody to iNOS on archival formalin fixed, paraffin embedded tissues of 5 normal oral mucosal samples, 10 Leukoplakia, 10 oral submucous fibrosis (OSMF) and 15 OSCC of different grades. RESULTS: A statistical significant difference was found between normal oral mucosa, precancer and OSCC in expression of iNOS (p value 0.0015). However, there was no statistically significant difference between the expressions of iNOS within premalignant groups (p value 0.5647) and histological sub-groups of OSCC (p value-0.5647). There was no statistically significant difference in the intensity of iNOS expression within the precancer group, OSCC sub-groups and between precancer and OSCC (p value-0.623). CONCLUSION: The orderly increase in the expression of iNOS from normal, through precancer, to OSCC suggests the essential role played by iNOS in epithelial transformation and tumour formation.