GLUTATHIONE-S-TRANSFERASE EXPRESSION IN RENAL-CELL CARCINOMA - A NEW MARKER OF DIFFERENTIATION

Expression of two GST isoenzymes (alpha and pi) was assessed immunohistochemically in 46 cases of renal cell carcinoma (RCC) for which clinical follow-up was available. In the normal kidney GST alpha stained most intensely in the proximal convoluted tubules and GST pi in distal tubules/collecting ducts. All 46 tumors studied stained positively for GST alpha with most demonstrating strong cytoplasmic and nuclear reactivity. GST pi immunostaining was positive in 35/46 cases (76%). Five-year survival for patients with GST pi positive tumors was 88% versus 50% for those with GST pi negative tumors (P < 0.008). Loss of GST mRNA has been reported in RCC and it has been suggested that this may represent a dedifferentiation program in RCC. These data support this hypothesis and further indicate a potential value for GST pi as a prognostic indicator in RCC.