Antioxidant enzyme levels in oral squamous cell carcinoma and normal human oral epithelium

The antioxidant enzymes (manganese- and copper-zinc-containing superoxide dismutases, catalase and glutathione peroxidase) limit cell injury induced by reactive oxygen species. The purpose of the study was to determine whether human oral squamous cell carcinomas have altered antioxidant enzyme levels. This study is the first to undertake this task in human oral mucosa and squamous cell carcinoma.

Semiquantitative immunohistochemistry was used to examine 26 archived oral squamous cell carcinoma biopsies. Fourteen well-differentiated and 12 poorly differentiated tumors were examined, as were 12 specimens of oral mucosa. All sections were reviewed by two oral and maxillofacial pathologists, and image analysis of the immunostained sections was performed using NIH Image. Antioxidant enzyme staining intensities were compared in the different groups by Duncan's multiple range test.

In general, mucosal basal cells displayed lower antioxidant enzyme levels than spinous cells, and primary tumor cells displayed lower antioxidant enzyme staining intensities than did their normal cell counterparts. Moreover, poorly differentiated tumor cells showed lower antioxidant enzyme staining intensities than well-differentiated tumor cells. Manganese-containing superoxide dismutase staining intensities were, however, higher in well-differentiated oral squamous cell carcinomas than their normal cells of origin.

Detection of antioxidant enzymes may be a useful future marker in the molecular diagnosis of the oral cancer. Moreover, it may be possible to not only monitor the effectiveness of chemopreventive and therapeutic strategies in oral cancer using these enzymes, but to monitor tumor recurrence.