THE EXPRESSION OF PLACENTAL GLUTATHIONE-S-TRANSFERASE (GST-PI) IN HUMAN NORMAL SALIVARY-GLANDS AND TUMORS

Immunohistochemical localization of placental glutathione S-transferas e (GST-pi) in normal and inflammatory salivary glands (74 cases) and t umors (71 cases) was studied. In the normal and inflamed salivary glan ds of all locations (including major and minor salivary glands), the d uctal epithelial cells showed moderate to strong GST-pi staining, myoe pithelial cells showed weak staining and the acinar cells were negativ e. The staining pattern of the tumor cells was similar to that of thei r normal counterparts. The tumor cells were generally positive with GS T-pi staining except those tumor cells demonstrating acini differentia tion (serous cells in acinic cell carcinoma, mucous cells in mucinous cystadenoma and mucoepidermoid carcinomas). Most of the salivary gland tumors, benign or malignant, showed a weak GST-pi staining. Only muco epidermoid carcinomas demonstrated significantly increased GST-pi reac tivity compared to other tumors (p<0.0001), which may be a reflection of both malignancy and squamous differentiation of the tumor. The mark ed increase in GST-pi activity in mucoepidermoid carcinomas may be use ful in serological screening of recurrent and metastatic mucoepidermoi d carcinomas.