Effect of methionine‐deprived total parenteral nutrition on tumor protein turnover in rats

• Published in: Cancer 1995-10, Vol.76 (7), p.1275-1282
• Main Authors: Yoshida, Shogo, Yamasaki, Kokushi, Kaibara, Atsushi, Takagi, Kenmei, Noake, Toshihiro, Ishibashi, Nobuya, Kakegawa, Teruo
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; DNA, Neoplasm - biosynthesis; Host-tumor relations. Immunology. Biological markers; Leucine - biosynthesis; Liver Neoplasms, Experimental - blood supply; Liver Neoplasms, Experimental - metabolism; Liver Neoplasms, Experimental - pathology; Male; Medical sciences; methionine; Methionine - biosynthesis; Methionine - deficiency; Neoplasm Proteins - metabolism; Neoplasm Transplantation; Parenteral Nutrition, Total; protein breakdown; protein synthesis; Rats; Rats, Inbred Strains; Regional Blood Flow; RNA, Neoplasm - metabolism; tumor growth; Tumors
• ISSN: 0008-543X; 1097-0142
• DOI: 10.1002/1097-0142(19951001)76:7<1275::AID-CNCR2820760727>3.0.CO;2-Z

Background. Previous studies have shown that a methionine‐lacking diet inhibited tumor growth in rats. The aim of this study was to determine how methionine free total parenteral nutrition (MTPN) can result in the inhibition of tumor growth on tumor protein metabolism in rats. Methods. On day 0, AH109A rat ascites hepatoma cells were implanted subcutaneously into male Donryu rats (n = 68, body weight, 200‐225 gm). On day 10, a catheter for total parenteral nutrition (TPN) was placed and either MTPN or standard TPN solution was given for 5 days. On day 15, 1‐14C‐leucine was infused continuously to measure tumor protein synthesis. Tumor proteolysis was calculated from tumor regional blood flow, using the 85Sr‐microsphere injection method. Results. 1) Tumor weight was reduced with MTPN. 2) MTPN did not affect tumor protein synthesis, probably because endogenous methionine production was increased with MTPN (87.3 ± 13.5 μmole methionine/kg/hour vs. 218.6 ± 29.5, P < 0.01); however, MTPN caused an increase of tumor proteolysis (2.68 ± 0.53 μmole leucine/g/hour vs. 3.79 ± 0.73, P < 0.05). Conclusion. The enhanced tumor protein breakdown contributed to the inhibition of tumor growth that was found with the rats given the methionine free diet.