Differential expression of glutathione S-transferases in germ cell tumors of human testes.

Glutathione S-transferase (GST) isoenzymes alfa, mu and pi were assessed by Western blotting in normal testes, seminomas and non-seminomatous germ cell tumors (NSGCTs). GST alfa and mu were strongly expressed in all normal specimens (n = 6), the pi isoform, however, could not or barely be detected. Ten (92%) of 11 seminomas had GST pi and only 2 (16%) showed alfa expression. In contrast, twelve (80%) of 15 NSGCTs showed a significant level of GST alfa and only 2 (13%) had GST pi expression. The absence or paucity of mu isoform was characteristic for all neoplastic testicular tissues. A statistically significant relationship (P = 0.021) could be established between GST alfa and stages of disease, i.e., alfa isoform was prevalent in the later stage (IIB, III) NSGCT tumors. These results suggest that the poor prognosis of the later stage NSGCTs may be due to their high GST alfa content, while the GST pi does not seem to have role in this relation.