EVALUATION OF GLUTATHIONE-S-TRANSFERASE ACTIVITY IN HUMAN BUCCAL EPITHELIAL DYSPLASIAS AND SQUAMOUS-CELL CARCINOMAS

Glutathione S-transferase (GST) activity and amount of GST alpha, mu a nd pi isoforms were measured in 40 patients with histopathologically c onfirmed oral epithelial dysplasia (OED) and squamous cell carcinoma o f buccal mucosa. The results were compared with those of normal mucosa in an equal number of age and sex-matched healthy controls. Mean tota l GST activities were significantly elevated from normal buccal mucosa for mild OED, moderate OED, severe OED and squamous cell carcinoma. G ST activity of value approximating 100 nmol/min/mg distinguished betwe en normal and dysplasia, and of value about 400 nmol/minimg delineated between dysplasia and squamous cell carcinoma were observed. GST pi w as the predominant class in both the diseased and normal buccal mucosa examined. This class pi GST was present at an intracellular concentra tion, which was significantly higher in diseased buccal mucosa than in normal buccal mucosa. These results indicated that pi class GST was t he major form of this enzyme in the cytosolic fraction of oral mucosa. The severity of OED related to squamous cell carcinoma development se emed to increase concomitantly with an increase in the level of this e nzyme. Further studies will validate the role of GST pi estimation in predicting the potential malignancy of OED.