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Purine-metabolizing Enzymes in Normal Rat Liver Nandovikoff Hepatoma^{* ,}

Gaston de Lamirande, Claude Allard and Antonio Cantero

( Research Laboratories, Montreal Cancer Institute, Notre Dame Hospital, Montreal, Canada)

The levels of activity and the intracellular distribution of 5'-nucleotidase, nucleoside phosphorylase, adenosine deaminase, guanase, adenase, xanthine oxidase, and uricase have been determined in normal liver and in Novikoff hepatoma. The activities of 5'-nucleotidase, nucleoside phosphorylase, guanase, and adenase were greatly diminished, whereas that of adenosine deaminase was increased in the transplanted hepatoma as compared with normal liver. Xanthine oxidase and uricase activities could not be demonstrated in the tumor transplant. The intracellular distributions of the enzymes studied were similar in both the liver and hepatoma tissues. These findings suggest that the catabolism of purines and purine derivatives is not only deeply impaired but completely blocked at the stage of xanthine and hypoxanthine.

^* This investigation was supported by a grant from the National Cancer Institute of Canada.

Parts of this work have been presented before the American Association for Cancer Research, Proc. Am. Assoc. Cancer Research, 2:128, 1956, and 224, 1957, and at the Symposium on the Novikoff Hepatoma, Held During the 2d Canadian Cancer Conference, June, 1956.

Research Associate of the National Cancer Institute of Canada.

Received 4/18/58.