Tumor and host tissue responses to branched-chain amino acid supplementation of patients with cancer M A McNurlan, S D Heys, K G M Park et al Clinical Science 1994; 86: 339-345.
The metabolic effects of intravenous nutrition (IVN) with branched chain amino acid (BCAA) enriched solutions on skeletal muscle and tumor were investigated in patients with colorectal cancer. Patients (n = 26) undergoing surgical removal of clinically localized tumors were allocated to 3 treatment groups: fasted, conventional IVN or BCAA supplemented (30% of nitrogen as BCAA). Nutritional treatments started 20 h before surgery and protein synthesis was assessed in vivo using a flooding dose technique with L-[1-13C]leucine. The plasma level of most amino acids was higher in the fed groups than in the fasted group; the level of BCAA was increased in the BCAA fed group. Conventional IVN stimulated protein synthesis in tumor (+94%) and in skeletal muscle (+48%) compared to the fasted group; this effect was less pronounced in the BCAA group (+49% and +19% respectively). Anti-proliferative cell nuclear antigen (PCNA) expression in the tumors was increased in both fed groups compared to the fasted state, and correlated with the rate of protein synthesis. It is concluded that the rate of tumor growth can be influenced by the composition of nutrient infused. However, BCAA seems to provide no clear advantage over a conventional IVN, since lower stimulation of tumor protein synthesis was associated with a lower stimulation of muscle protein synthesis.
Le Bricon
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Department of Animal Science, University of Alberta Edmonton, Alberta T6G 2P5, Canada.