Growth inhibition of subcutaneously transplanted hepatomas without cachexia by alteration of the dietary arginine‐methionine balance

Abstract

Previous studies have shown that alteration of the dietary arginine‐methionine balance by use of synthetic L‐amino acids inhibits tumor growth of a subcutaneously transplanted Morris hepatoma at the expense of maintaining body weight. However, L‐methionine is susceptible to degradation and, therefore, may contribute to a deficiency state. The present studies were performed to determine whether growth of subcutaneous hepatoma transplants is inhibited, and body growth maintained, when rats are fed diets containing L‐methionine in replacement of N‐acetyl‐L‐methio‐nine (NALM) for 28 days. Tumor‐free and tumor‐bearing rats fed a control diet, with amino acids replacing protein, had gains in body weight: 31.3 ± 1.0 and 19.1 ± 0.5 g (12% and 7%), respectively. Rats fed six experimental diets, with varying L‐arginine‐NALM balances, had body weight gains ranging from 18.4 ± 0.3 to 26.7 ± 0.9 g (7–10%). Tumor weight of control rats was 10.65 ± 0.24% of body weight. Diets supplemented with L‐arginine in combination with normal and deficient NALM decreased tumor weights by 35% and 38%, respectively. It is concluded that dietary replacement of L‐methionine with NALM and supplementation with L‐arginine inhibits growth of a subcutaneously transplanted Morris hepatoma in the absence of cachexia.