GLUTATHIONE-RELATED ENZYMES IN HUMAN TESTICULAR GERM-CELL TUMORS AND NORMAL TESTES

In this study, the activity of the glutathione related enzymes, namely glutathione S-transferase (GST), glutathione reductase (GSSG-R), Sele nium-dependent and -independent glutathione peroxidase(GPX) of various TGC tumors (n=18) obtained from untreated patients, was compared to t hat;of the cor-responding enyzmes of normal testicular tissues (n=5). The enzymes of all tumorous tissues except teratomas were significantl y less active,than the corresponding enzymes of nontumorous tissues. T he GST was in seminomas 4.3-20-, in embryonal carcinomas 47-, and in m ired tumors 13-47-fold less active than in the normal testes. The GST activity of tetratomas was about half of that of the normal tissues. T he Se-independent GPX, component of GST alfa class,comprised about 90 percent of the total GPX activity in normal testis; however it was abs ent or barely detectable in all TGC tumors except teratomas. The latte r had about the same GPX activity as the tumor-free testicular tissues . Apart from the teratoma, the GSSG-R activity of all TGC tumors was a lso suppressed to about one third of that of the normal testis. The in sufficient function of glutathione related enzymes of TGC tumors may c ontribute to their sensitivity against treatment. The poorer prognosis of tetratomas, however, may be explained by the relatively higher act ivity of their detoxifying enzymes.