Do tobacco stimulate the production of nitric oxide by up regulation of inducible nitric oxide synthesis in cancer: Immunohistochemical determination of inducible nitric oxide synthesis in oral squamous cell carcinoma--a comparative study in tobacco habituers and non-habituers.

Background: Oral cancer accounts for 6% of all cancers. The most prevalent form of oral cancer is oral squamous cell carcinoma (OSCC), which accounts for 90% of the oral cancer cases. The major risk factor for development of OSCC is the use of tobacco in various forms. NO has been studied widely over the years due to its role in various physiological and pathophysiological processes, including its complex role in carcinogenesis.

Materials And Methods: A total of 20 cases of OSCC in tobacco habituers and tobacco non-habituers were retrieved respectively from the archival biopsy specimens. Immunohistochemistry was done to assess the inducible nitric oxide synthase (iNOS) protein.

Results: This study was performed to assess the correlation between tobacco and nitric oxide in OSCC in order to know the association of these two in the process of carcinogenesis. The results showed the enhanced expression of iNOS in tobacco habituers in comparison with tobacco non-habituers. Though the increased expression of iNOS is found, significant difference is not obtained with scores, but significant difference was found with intensity of staining.

Conclusions: The results of the present study indicate the enhanced expression in OSCC of tobacco habituers when compared to OSCC of tobacco non-habituers indicating the effect of tobacco on nitric oxide. Carcinogenic chemical compounds in Tobacco induce nitric oxide production by iNOS, by its tumor-promoting effects which may enhance the process of carcinogenesis.