[Correlation between the growth of transplantable tumors under protein deprivation and intratumoral amino acid concentration].

Nutritional restriction in the diet has a deleterious influence on tissue and transplantable tumor growths. Correlation between the growth of 81 B or MM 48 mammary tumors and intratumoral amino acid concentration was studied in syngeneic C3H/He mice fed a diet with a low (D) or normal (N) protein content. D-mice revealed a relatively longer lag phase than N-mice, but showed almost the same growth curve. Some kinds of amino acid, alanine, valin, glycine, and so on were recognized in D-mice tumors at higher levels more than in N-mice. In protein malnutrition, urea, the final amino acid degradation product, was not detected in the transplanted tumor or muscle of D-mice. The high tissue levels of alanine, glycine and glutamine are undoubtedly related to their participation in many metabolic reactions, so that they are readily and extensively synthesized. We speculate that D-mice would maintain an adequate intratumoral amino acid level through interorgan relationships in order for the transplanted tumor to grow.