Introduction: In our previous study, glutathione S-transferase-pi (GST-pi), a phase II drug metabolizing enzyme, was found to be expressed in pancreatic ductal and ductular cells but not acinar cells of the normal pancreas, chronic pancreatitis, and secondary pancreatitis caused by pancreatic cancer. A greater percentage of the cells expressing GST-pi was shown in the islets of chronic pancreatitis specimens compared with the normal pancreas and secondary pancreatitis.
Aims and methodology: To examine whether the increased number of islet cells expressing GST-pi and the absence in the acinar cells are compensated for by other GST isozymes, we investigated the expression of GST-alpha and GST-mu in the same specimens.
Results: Unlike the distribution of GST-pi, the distribution of GST-alpha and GST-mu in islets did not show marked differences between the three groups. However, in four of 18 primary chronic pancreatitis specimens, more islet cells (approximately 25%) expressed GST-alpha than in the normal pancreas and secondary chronic pancreatitis (both approximately 10%). The reactivity of cancer cells to GST-alpha, GST-mu, and GST-pi was similar to the ductal cells in the normal pancreas, chronic pancreatitis, and secondary chronic pancreatitis. Contrary to the expression of GST-pi, no statistically significant differences were found in the distribution of GST-alpha and GST-mu in the normal pancreas, chronic pancreatitis, and secondary chronic pancreatitis.
Conclusion: The expression of the other GSTs does not compensate for the variation of expression of GST-pi. There was no specimen in each group that did not express at least one GST isozyme in islet, acinar, and ductal cells.