Differential expression of glutathione S-transferase, glutathione peroxidase and glutathione reductase in normal and malignant human breast tissues

In the present study we have compared the levels of glutathione (GSH) S-transferase, GSH peroxidase and GSH reductase in human breast tumors and adjacent normal tissues obtained from the same individuals. We have also quantitated GST π type antigen in these samples by western blotting. GST π activity towards 1-chloro-2,4-dinitrobenzene was found to be elevated in tumors from three out of six patients (patient nos. 2, 4 and 5), whereas this activity was suppressed in tumor from patient no. 1. Results of Western blotting using antibodies raised against GST π of human placenta were in agreement with the GST activity data. GSH peroxidase activity with cumene hydroperoxide as substrate was found to be elevated in four tumor samples (patients nos. 2, 4, 5, and 6) but suppressed in tumor from patient no. 1. On the other hand, GSH reductase activity was elevated in three samples (patients nos. 2, 4 and 5) and downregulated in the remaining three samples (patients nos. 1, 3 and 6). These results indicate that GSH-related enzymes are differentially altered in human breast tumors and GST π type isoenzyme(s), unlike certain other human carcinomas such as colonic, are not uniformly elevated in human breast tumors.