Immunohistochemical Observation of Placental Form of Glutathione S-Transferase in Squamous Cell Carcinoma

ABSTRACT

Glutathione S-Transferase (GST) is a conjugation enzyme in the metabolism of exogenous and endogenous lipophilic compounds for their excretion and detoxification. Acidic isozyme of GST, GST-Pi, has been recognized as a preneoplastic marker in the experimental hyperplastic nodules of liver in rats, and GST-Pi is abundant in the squamous cells of the skin, also. This histochemical study was carried out to evaluate the distribution and the relationship between the differentiation status of squamous cells in dysplastic or neoplastic epithelium in various organs. The human placental form of glutathione S-transferase (GST-Pi) were stained immunohistochemically with specific anti GST-Pi rabbit antibody in 23 cases of human squamous cell carcinomas. The patients consisted of 14 cases from the uterine cervix, 3 cases from the esopahgus, 3 cases from the lung and 3 cases from the larynx. The results obtained were as follows; 1. Basal cells in normal mucosa were stained negative for GST-Pi while superficial keratinocytes were stained moderately positive. Basal dysplastic cells were stained negatively or weakly positive. Carcinoma cells especially large cells either keratinizing or nonkeratinizing were stained moderately to strongly. Carcinoma cells surrounding keratin pearl were strongly reacted with GST-Pi than other carcinoma cells. 2. Differentiated cells of squamous cell carcinoma showed moderate to strong positive reaction to GST-Pi staining irrespective of its site of origin. 3. Therefore, Immunohistochemical staining pattern of GST-Pi in various squamous carcinoma cells showed similar immunohistochemical reaction to the GST-pi, which is closely correlated to the degree of differentiation, keratinigation and also suggested that squamous carcinoma cells had abundant GST-Pi related detoxifying system.