Impaired insulin action on phosphatidylinositol 3-kinase activity and glucose transport in skeletal muscle cancer patients

Introduction: Glucose intolerance or overt diabetes occurs in 80% of patients with pancreatic cancer (PC). This associated metabolic disorder includes peripheral insulin resistance, which may be caused by factors produced by the PC. The mechanism underlying PC-associated insulin resistance has not been clearly defined. Aim: To characterize basal and insulin- stimulated glucose transport, phosphatidylinositol (PI)3-kinase activity, and glucose transporter 4 (GLUT4) in skeletal muscles of PC patients. Methodology: Skeletal muscle samples were obtained from the abdominal wall of 17 PC patients during surgery. Control muscles were sampled in the same way from 11 donors undergoing abdominal surgery for benign diseases. PI3-kinase activity, glucose transport, and GLUT4 were assessed in vitro in these muscles. Results: In presence of physiologic concentrations of insulin, glucose transport and PI3-kinase activity were significantly decreased in the PC group compared with controls. At supraphysiologic insulin concentrations, glucose transport was significantly decreased but PI3-kinase activity was normalized. In the absence of insulin, these parameters were not significantly different between PC and control groups. Muscle GLUT4 contents were similar between PC and control groups. Conclusion: Defects in insulin-mediated PI3-kinase activity and glucose transport contribute to the insulin resistance in patients with PC.