GLUTATHIONE S-TRANSFERASES IN ESOPHAGEAL CANCER

Glutathione content and glutathione S-transferase enzyme activity as w ell as isoenzyme composition were studied in normal gastric cardia, no rmal squamous esophageal epithelium and corresponding malignant tumor of 10 patients with esophageal cancer. Mean values of glutathione (38 +/- 6 versus 36 +/- 12 nmol/mg protein) and glutathione S-transferase activity (532 +/- 44 versus 532 +/- 108 nmol/min mg protein) did not d iffer significantly between normal esophageal and tumor tissue. Howeve r, great individual differences exist. In two patients, glutathione S- transferase activity was much higher in the tumor (1081 and 1381 nmol/ min mg protein) due to overexpression of class alpha, mu and pi glutat hione S-transferases in one case, and of class mu and pi in the other case. In the other patients, glutathione S-transferase activity was eq ual (one case) or lower (seven cases) in the tumor. In normal gastric cardia glutathione content as well as glutathione S-transferase activi ty was significantly lower as compared to normal esophageal epithelium . In conclusion, in contrast to other gastrointestinal tumors, glutath ione S-transferases are overexpressed in esophageal tumors in only a l imited number of patients.