Lewis lung carcinoma cells regulation of stretch‐induced mTOR activation in C2C12 myotubes (1163.8)

Abstract

Imbalances in rates of protein synthesis and degradation are responsible for cancer‐induced skeletal muscle wasting. Lewis lung carcinoma (LLC) cell implantation is a widely used explant mouse model for examining cancer cachexia and muscle wasting. We have demonstrated that trans‐signaling molecules from LLC cells resulted in mTOR suppression in C2C12 myotubes and muscle from mice implanted with LLC tumors. Mechanical overload activates mTOR signaling and increases protein synthesis rate, serving as a potential therapeutic strategy for skeletal muscle mass maintenance. The purpose of this study is to investigate the effect of mechanical stretch on C2C12 myotube protein synthesis regulation in the presence of trans‐signaling molecules from LLC cells. C2C12 myotubes were differentiated and then stretched on collagen‐coated silastic membranes. Chronic uniaxial stretch (5% for 24h) induced ERK (T202/Y204) and S6 ribosomal protein (S235/236) phosphorylation as well as rate of protein synthesis in control medium (DMEM with 2.5% FBS). However, the addition of LLC medium blocked the stretch induction of S6 ribosomal protein phosphorylation. These results suggest LLC can directly suppress mechanical activation of signaling that regualtes of skeletal muscle protein synthesis.