Measurement of glutathione S-transferase and its class-pi in plasma and tissue biopsies obtained after laparoscopy and endoscopy from subjects with esophagus and gastric cancer.

OBJECTIVES: To develop an indirect enzyme-linked immunosorbent assay (ELISA) for measuring class-pi glutathione S-transferase (GST) in plasma, and tissue biopsies obtained from upper gastrointestinal cancer (UGI Ca) patients. METHODS: GST activity and GST-pi concentration were detected in normal human squamous esophageal epithelium, normal gastric cardia and their corresponding malignant tumor biopsies. RESULTS: Plasma GST was significantly higher (p < 0.05) in UGI Ca patients as compared to those obtained from normal individuals. Plasma GST-pi concentration in normal subjects was 6.6 +/- 1.9 ng/mg protein, whereas it was higher in UGI Ca patients (esophageal, 10.0 +/- 1.8; gastric, 10.7 +/- 1.7 ng/mL, p