Glutathione S-transferase in human esophageal carcinoma.

The expression of human glutathione S-transferase-pi (GST-pi) in esophageal squamous cell carcinoma and in corresponding morphologically normal mucosa from 17 patients was examined by Northern blots, in situ hybridization and immunohistochemistry. Relative GST-pi expression (tumor/mucosa) ranged from 0.31 to 1.52 (0.821 +/- 0.40: mean +/- SD), and only 6 out of 17 cases demonstrated increased GST-pi transcripts in tumor tissue over normal tissue. In situ hybridization and immunohistochemistry showed that morphologically normal esophageal mucosa, especially in its basilar two thirds, expressed the enzyme as strongly as did carcinoma cells. No significant correlation was observed between the amount or pattern of GST-pi expression by carcinomas and the clinicopathological findings in the cases. The marked expression of GST-pi by non-pathologic mucosa obtained from the patients with esophageal carcinoma suggests that GST-pi may be a marker of increased carcinogen exposure, but not necessarily a marker of developed human esophageal cancer.