Expression of glutathione S-transferases in normal and malignant pancreas: an immunohistochemical study

The glutathione S-transferases (GSTs) are a family of detoxification and metabolising enzymes, which have been linked with the susceptibility of tissues to environmental carcinogens and resistance of tumours to chemotherapy. Environmental carcinogens have been implicated in the pathogenesis of pancreatic carcinoma, which is also a tumour characterised by marked chemotherapeutic drug resistance. In this study 26 pancreatic adenocarcinoma and 12 normal pancreatic samples were examined immunohistochemically for expression of pi (acidic), alpha (basic), and mu (neutral) GST. Fourteen (54%) of the tumours expressed pi GST alone, two (8%) expressed both pi and alpha GST, and two (8%) showed immunoreactivity with alpha GST alone. In the normal pancreas the intralobular ducts and centroacinar cells expressed pi GST alone whereas the large ducts expressed both pi and alpha GST. The acinar cells showed immunoreactivity only with anti-alpha GST. Mu GST was not expressed by normal or malignant pancreas. Expression of pi GST by pancreatic carcinoma may be a marker of the malignant phenotype and be induced during neoplastic transformation. Alternatively it could possibly reflect cell of origin, suggesting that the tumour arises from the centroacinar cells or intralobular ducts, or both rather than the large ducts.