Increased protein nitrosylation in head and neck squamous cell carcinogenesis

Background. Nitric oxide (NO·) and its metabolic byproducts are implicated in carcinogenesis. We examined a marker of NO·- species' pathologic protein nitrosylation, nitrotyrosine, during head and neck squamous cell carcinoma (HNSCCa) development. Materials and Methods. Paraffin-embedded tissue samples of normal oral mucosa, squamous hyperplasia/dysplasia, and HNSCCa were immunohistochemically analyzed for staining intensity using an antinitrotyrosine monoclonal antibody, and correlated with retrospective clinical data. Results. Significantly higher staining was noted in reactive, dysplastic and HNSCCa samples compared with samples of normal mucosa. Additionally, significant differences in staining were found between various primary sites of the upper aerodigestive tract. Lastly, individual inflammatory cells also stained intensely. Conclusions. Increasing amounts of nitrotyrosine staining were found in reactive/dysplastic and HNSCCa lesions compared to normal squamous mucosa. Inflammatory cell staining implicates NO· as a possible mediator of immunosuppression. Given these findings, the role of NO· in mutations leading to and the immunosuppression found in HNSCCa warrants further investigation.