Effects of leucine rich diet on translation eukaryotic initiation factors in skeletal muscle of tumour-bearing pregnant rats

Abstract

Cancer-cachexia induces a variety of metabolic disorders in protein metabolism that involves a decrease in protein synthesis and an increase in protein degradation. Insulin, other hormones and nutrients, such as branched chain amino acids, especially leucine, stimulate protein synthesis and module the activity of a number of translational initiation factors in protein synthesis mechanism. Pregnant rats were implanted or not with Walker 256 tumour and distributed into six groups: three groups were fed with the control diet (18% casein): C pregnant control, W tumour-bearing, and P pair-fed, which received the same amount of food as ingested by the W group; three other pregnant groups were fed with the leucine-rich diet (3% leucine plus 15% casein): L pregnant leucine, WL tumour-bearing, and PL pair-fed, which received the same amount of food as ingested by the WL group. The gastrocnemius muscle of WL groups increased the leucine and KIC incorporation to protein compared to W rats. Leucine-rich diet prevent the plasma insulin reduction. The translational initiation factors were improved when the tumour-bearing rats were fed a leucine-rich diet; and eIF5 expressions were around 35% increased; eIF4E and eIF4G were around 17% and 20% higher then W group; and S6K1 and PKC were 50% and 56% enhanced, respectively. The leucine-rich diet increased protein synthesis in skeletal muscle in tumour-bearing rats and enhanced many signalling factors, probably interfering in protein synthesis by the eIF factors and/or activating the S6kinase pathways. (AU)