Determination of the activity levels of adenosine deaminase, xanthine oxidase, nitric oxide synthase and nitric oxide in oral cavity cancers

SUMMARYHead and neck cancers represent a major international health problem, accounting for the fifth most common type and cause of cancer related death worldwide. Oral cavity cancers are the most common in the head and neck cancers and has a high mortality. Although certain risk factors for the development of head and neck squamous cell carcinoma including alcohol, tobacco, nutrition, viral infection and poor dentition are known; however these do not adequately explain %5?10 of cases. Chronic inflammation has long been recognized as being associated with increased risk for human cancer at various sites and as an important component of tumorogenesis, although the mechanisms involved are not fully characterized. Carcinogenesis studies emphasizes that carcinogenic substances are needed to be metabolized by the body's enzyme systems. As this accepted hypothesis, these chemicals turn to the electrophilic metabolites (radicals) in the body and, these lead to the activation of oncogenes caused by DNA damage. Nitric oxide (NO) and nitric oxide synthase (NOS) play important roles in carcinogenesis, with the effects to inflammation process and oxidan and antioxidan effects. ADA (adenosine deaminase) and XO (xanthine oxidase) are the purine metabolic pathway enzymes. ADA is known to be essential for cell-mediated immunity, in carcinogenesis this enzyme is also important in terms of increased cell proliferation. XO (xanthine oxidase) plays a role as a basis of free radicals in the mechanism of carcinogenesis.In this study, oral cavity carcinoma tissues were compared with tumor-free control tissues; ADA, XO, NO, NOS activities were evaluated in terms of 72 difference. Seventeen patients with cancerous tissue and adjacent normal mucosa were obtained during resection.There were no significant correlations between enzyme- molecule activity levels and age, alcohol and smoking habits, tumor size, lymph node and distant metastasis stage. No statistically significant difference was observed in terms of XO activities. In tumor tissues, NO and NOS activities were observed as decreased but not statistically significant, ADA activities were observed as statistically significant increased. In our study In our study, in the view of the fact that tumor and control samples were taken from the same cases, NO and NOS activities were also seen in the peritumoral tissue (except in tumor tissue); this finding is compatible with the knowledge of the literature. The activity in tumor tissue is thought to be the result of carcinogenesis and peritumoral tissue activity is thought to be the result of inflammation. Increased ADA activity which increased with the increase in cellular proliferation in tumor tissue, is a result of purine metabolism. In this context, an agent that inhibites ADA, is thought to be a glimmer of hope in patients with oral cavity cancer.