Glycine and adenine as precursors of nucleic acid purines in tumor-bearing mice.

Certain purines, notably adenine, are readily incorporated into the nucleic acids of rat tissues (1). Studies with glycine, a specific precursor involved in the synthesis of purines, in the same animal have shown (2, 3) relative uptakes in the ribose nucleic acid (RNA) and deoxyribose nucleic acid (DNA) fractions which are somewhat different from those obtained with adenine (4). A simultaneous administration of adenine-Cl4 and glytine-N15 has substantiated the different relative incorporation into the DNA and RNA of rat liver (5). An analogous differential between the incorporations of adenine-N15 and formate-C14, another precursor of purines (6, 7), has also been demonstrated in rat liver (8). The differences between preformed purine incorporation and purine synthesis de novo from small precursors have not been as clearly demonstrated in the mouse. The fact that the rat shows an extremely small utilization of preformed guanine (9), while the C57 black mouse utilizes guanine to a more significant extent (lo), indicates that species differences in nucleic acid anabolism may be quantitative rather than qualitative. It seemed to be of interest to determine whether the divergence in utilization of preformed purines versus precursors de novo in the mouse is qualitatively similar to that in the rat (11, 12). In addition, information was desired concerning the relative utilization of exogenously supplied adenine and de novo synthesis of nucleic acid purines in tumor tissue. Accordingly, this communication reports the results of simultaneous administration of adenine-8-Cl4 and glycine-N15 to Swiss Webster white mice bearing sarcoma 180. The nucleic acids, and the individual purines therefrom, of pooled liver, tumor, intestine, and spleen were examined for isotope content.