The incorporation of several C14-labeled purine precursors into the PNA of rats carrying a human tumor, HS #1 (Toolan), has been determined. The utilization by the tumor, intestine, liver, kidney, and spleen has been measured. Comparison of the values with those previously obtained with hamsters carrying human tumors indicates that certain effects of tumors on host metabolism are independent of the species. These are (a) increased utilization of adenine by the liver, (b) increased utilization of hypoxanthine for synthesis of PNA of liver and intestine, and (c) a general increase in glycine uptake.

The results support the concept that tumors preferentially synthesize nucleic acid purines de novo rather than utilize exogenously supplied purines. The tumors appear to possess metabolic characteristics distinguishable from those of the host.


This investigation was supported by funds from the National Cancer Institute, National Institutes of Health, Public Health Service (Grant C-471), and from the Atomic Energy Commission (Contract AT(30-1)-910).

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