Expression of inducible nitric oxide synthase (iNOS) in oral precancer and oral squamous cell carcinoma: an immunohistochemical study.
OBJECTIVE
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).


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).


CONCLUSIONS
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.
Department of Oral and Maxillofacial Pathology, Mar Baselious Dental College and Hospital, Kothamangalam, Kerala, India. drsomasusan@yahoo.in
Soma Susan
SS
Varghese
P M
PM
Sunil
R Nirmal
RN
Madhavan
D000911:Antibodies, Monoclonal; D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D009061:Mouth Mucosa / Q000378:metabolism*; D009062:Mouth Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D009569:Nitric Oxide / Q000096:biosynthesis*; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis* / Q000235:genetics; D011230:Precancerous Conditions / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis
D000911:Antibodies, Monoclonal; D012333:RNA, Messenger; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II