GLUTATHIONE TRANSFERASE GST PI IN BREAST-TUMORS EVALUATED BY 3 TECHNIQUES

The glutathione transferases are involved in intracellular detoxificat ion reactions. One of these, GSTpi, is elevated in some breast cancer cells, particularly cells selected for resistance to anticancer agents . We evaluated GSTpi expression in 60 human breast tumors by three tec hniques, immunohistochemistry, Northern hybridization, and Western blo t analysis. There was a significant positive correlation between the t hree methods, with complete concordance seen in 64% of the tumors. The re was strong, inverse relationship between GSTpi expression and stero id receptor status with all of the techniques utilized. In addition, t here was a trend toward higher GSTpi expression in poorly differentiat ed tumors, but no correlation was found between tumor GSTpi content an d DNA ploidy or %S-phase. GSTpi expression was also detected in adjace nt benign breast tissue as well as infiltrating lymphocytes; this expr ession may contribute to GSTpi measurements using either Northern hybr idization or Western blot analysis. These results suggest that immunoh istochemistry is the method of choice for measuring GSTpi in breast tu mors.