Immunohistochemical Localization of Glutathione S‐Transferase α and π in Human Esophageal Squamous Epithelium, Barrett's Epithelium and Carcinoma

High tissue levels of glutathione S‐transferases (GSTs), a family of detoxification enzymes, are inversely correlated with cancer risk in the human gastrointestinal tract. Patients with Barrett's esophagus, wherein squamous epithelium is replaced by columnar epithelium, have an increased risk for developing esophageal adenocarcinoma. Biochemical analyses revealed that Barrett's epithelium contains lower levels of GST enzyme activity as well as some GST isoforms, as compared with squamous epithelium. So far, little information on the immunohistochemical distribution of the GST α and π isoforms in normal squamous epithelium, in Barrett's metaplastic epithelium or in adeno‐ and squamous cell carcinomas of the esophagus is available. Tissues were fixed in formalin and embedded in paraffin. Three 4 μm thick sections were used for hematoxylin and eosin staining and for immunostaining with antibodies against GST α and π. GST α and π were seen in normal squamous epithelium (0% and 75%, respectively), Barrett's epithelium (75% and 100%), adenocarcinoma (25% and 100%) and squamous cell carcinoma (27% and 91%). Staining was mainly cytoplasmic, though some nuclear staining with the GST π antibody was apparent. The varying expression of GST α and π in normal and (pre)neoplastic esophagus may have consequences for the treatment of these diseases and may contribute to an understanding of the development of these esophageal disorders.