Expression of glutathione s-transferase II in benign mucosa, Barrett's metaplasia, and adenocarcinoma of the esophagus

Background. Glutathione s-transferase π (GSTπ) is an enzyme that provides cellular protection against redox-mediated damage by free radicals, which have been implicated in carcinogenesis. Methods. Forty-three consecutive specimens from 19 patients were reviewed to identify samples of squamous mucosa, Barrett's metaplasia, adenocarcinoma, and peritumoral inflammation. Serial sections were stained with an anti-GSTπ polyclonal antibody, and GSTπ expression was quantified for each histologic group. Results. GSTπ expression was diminished in peritumoral mononuclear inflammatory cells (p < .001) compared with squamous epithelium, Barrett's metaplasia, or adenocarcinoma. Barrett's metaplasia exhibited decreased GSTπ expression compared with squamous mucosa (p = .045). GSTπ expression by >50% of adenocarcinoma cells was associated with an increased risk (2.25x) of disease at last follow-up. Conclusions. GSTπ is prominently expressed in esophageal squamous mucosa and adenocarcinoma. Mononuclear cells may be susceptible to oxidative damage secondary to weak GSTπ production. GSTπ may protect the tumor cells themselves from the cytotoxic effects of free radicals. The biochemical role of GSTπ expression in malignant transformation deserves further investigation.