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

BACKGROUND

Glutathione s-transferase pi (GSTpi) 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-GSTpi polyclonal antibody, and GSTpi expression was quantified for each histologic group.

RESULTS

GSTpi expression was diminished in peritumoral mononuclear inflammatory cells (p <.001) compared with squamous epithelium, Barrett's metaplasia, or adenocarcinoma. Barrett's metaplasia exhibited decreased GSTpi expression compared with squamous mucosa (p =.045). GSTpi expression by >50% of adenocarcinoma cells was associated with an increased risk (2.25x) of disease at last follow-up.

CONCLUSIONS

GSTpi is prominently expressed in esophageal squamous mucosa and adenocarcinoma. Mononuclear cells may be susceptible to oxidative damage secondary to weak GSTpi production. GSTpi may protect the tumor cells themselves from the cytotoxic effects of free radicals. The biochemical role of GSTpi expression in malignant transformation deserves further investigation.