Abstract
This study was performed to examine the correlation between expression of active oxygen scavengers of free radicals and the development of Precancerous lesions or carcinoma of the oral epithelium. Methods : Tissue specimens consisted of the gingival and palatal epithelium from normal controls and from patients with lichen planus, leukoplakia, and squamous cell carcinoma (SCC), in cases of SCC, we also examined the associated non-hyperplastic epithelium (NHE) and the hyperplastic epithelium (HE) located between SCC and the NHE. lmmunostaining for copper-zinc superoxide dismutase (CuZn-SOD) and glutathione S-transferase-π (GST-π) was performed by the so-called ABC method.
Results : Expression of CuZn-SOD was detected in the basal cells of the normal oral epithelium, while immunostaining for GST-π was negative. The epithelium from lesions of oral lichen planus gave negative immunoreactions for both enzymes. In leukoplakia, both enzymes were strongly expressed throughout the epithelial cells, and a positive immunoreaction for GST-π was more frequent in cases of leukoplakis with dysplasia (57.1 % of cases) . In SCC, we detected intense immunoreaction specific for both enzymes in all neoplastic cells, and the frequency of immunodetection of GST-π was high (87.5%) . In the HE, we recognized a diffuse positive immunoreaction for CuZn-SOD in some cases, while the NHE was immunoreactive in the basal cells. However, in all layers of the HE and NHE products of the immunoreaction for GST-π were diffusely distributed in 87.5% and 75% of cases, respectively. Co-expression of CuZn-SOD and GST-π was most frequent in the HE, followed by SCC, leukoplakia and the NHE.
Conclusion : Our results suggest that co-expression of both enzymes and, in particular, the expression of GST-π are closely associated with the development of carcinoma in the oral epithelium.
