Alteration of glutathione S-transferase levels in Barrett's metaplasia compared to normal oesophageal epithelium.

OBJECTIVE

Oesophageal cancer associated with the premalignant condition Barrett's oesophagus has increased in incidence over the last few years. Phase II detoxifying enzymes, including glutathione S-transferases (GSTs) protect the mucosa from carcinogens, which can cause oxidative damage to cells. Therefore, a reduction in these anti-oxidant enzymes can increase the risk of carcinogenesis. The aim of this study was to compare the extent of GST expression in normal oesophageal tissue, Barrett's oesophagus and oesophageal adenocarcinoma.

METHODS

Antibodies raised against GST alpha, GST mu, GST pi and microsomal GST were used to identify expression of these proteins in tissue sections.

METHODS

Paraffin-embedded sections were stained using standard immunohistochemical techniques to demonstrate the pattern of expression of GST proteins in biopsy specimens. Twelve sections of Barrett's metaplasia and an equal number of specimens from normal oesophageal tissue were examined, together with sections from adenocarcinoma and normal gastric mucosa.

RESULTS

Expression of the GST enzymes appeared to be reduced in Barrett's tissue compared to normal oesophageal tissue. Nuclear staining featured in some of the normal tissue sections, but not in Barrett's tissue.

CONCLUSIONS

The reduction in GST expression suggested in Barrett's tissue is an interesting finding, as it is possible that reduced expression of these detoxifying enzymes may contribute to the risk of development of adenocarcinoma in Barrett's mucosa.