Role of nitric oxide and antioxidant enzymes in the pathogenesis of oral cancer

Background: Oral cancer is the leading malignancy in India. Nitric oxide and antioxidant enzymes play an important role in etiology of oral cancer. Therefore, the present study evaluates nitric oxide and antioxidant enzyme levels in healthy individual without tobacco habits (NHT, N=30) and healthy individuals with tobacco habits (WHT, n=90), patients with oral precancers (OPC, n=15) and oral cancer patients (n=126).
Materials and Methods: Blood samples were collected from the subjects. NO₂ +NO₃ (nitrite+nitrate), superoxide dismutase (SOD) and catalase levels were estimated using highly specific spectrophotometeric methods. Statistical analysis was done by SPSS statistical software version 10.
Results: Mean plasma NO₂ +NO₃ levels were elevated in patients with OPC and oral cancer patients as compared to the controls. Mean activities of erythrocyte SOD and catalase were higher in WHT than NHT. Erythrocyte SOD and catalase levels were higher in WHT and patients with OPC as compared to NHT. The erythrocyte SOD and catalase activities were lower in oral cancer patients than patients with OPC. The erythrocyte SOD activity was higher in advanced oral cancer than the early disease. Erythrocyte catalase activity was lower in poorly differentiated tumors than well and moderately differentiated tumors. Pearson′s correlation analysis revealed that alterations in plasma NO₂ +NO₃ levels were negatively associated with changes in erythrocyte SOD activities.
Conclusion: The data revealed that the alterations in antioxidant activities were associated with production of nitric oxide in oral cancer, which may have significant role in oral carcinogenesis.

Keywords
Catalase, nitric oxide, oral cancer, oral precancers, superoxide dismutase