Enzymes of Purine Metabolism in Human and Rat Renal Cortex and Renal Cell Carcinoma2

Abstract

Activities of seven enzymes of purine metabolism were compared in human and rat renal cortex and in human and rat renal cell carcinoma. The enzymes adenosine deaminase, adenosine kinase, AMP deaminase, adenylosuccinate lyase, adenylosuccinate synthetase, GMP kinase, and IMP dehydrogenase were selected because they showed characteristic activity changes in hepatomas relative to normal liver. The activities of thase enzymes in human renal cortex were in the same range as, or lower than, their activities in rat kidney; the largest relative difference was in adenosine deaminase activity, which in human renal cortex was 36% of that in the rat. In renal cell carcinoma of human or rat, activities of AMP deaminase, adenylosuccinate lyase, adenylosuccinate synthetase, and IMP dehydrogenase were significantly higher (149–324%) than in the respective renal cortexes. GMP kinase activity in the tumors was in the same range as that in kidney cortex, and adenosine kinase activity was markedly decreased in the tumors relative to kidney in both species. Adenosine deaminase activity in rat kidney tumors was lower (20–22%) than in normal rat kidney, but activity in the human tumors was in the normal range. With the exception of adenosine deaminase, the behavior of these enzymes in kidney tumors relative to normal kidney resembled the changes seen in hepatomas as compared with normal liver. The close biochemical resemblances of the transplantable rat kidney tumors to the human renal cell carcinomas suggested that the experimental tumors used in this study may provide a suitable model system for chemotherapy of renal cell carcinoma.