Unmetabolized fenofibrate, but not fenofibric acid, activates AMPK and inhibits the expression of phosphoenolpyruvate carboxykinase in hepatocytes

Abstract

Aims A lipid-lowering agent, fenofibrate, has been reported to reduce hepatic glucose production and the expression of phosphoenolpyruvate carboxykinase (PEPCK), a rate-limiting enzyme for gluconeogenesis in the liver. However, the precise mechanisms of these effects have remained unclear. Main methods Rat hepatoma-derived H4IIE cells and murine myoblast-derived C2C12 cells were incubated with the ester form of fenofibrate and fenofibric acid, a metabolite of fenofibrate ester, and the phosphorylation of AMPK, acetyl-CoA carboxylase (ACC), PEPCK mRNA expression and glucose production were assessed. Key findings Incubation of H4IIE hepatoma cells with the ester form of fenofibrate increased the phosphorylation of AMPK and acetyl-CoA carboxylase (ACC) and decreased PEPCK mRNA expression and glucose production. Fenofibrate-induced reductions in PEPCK expression and glucose production were abrogated by compound C, a specific AMPK inhibitor. Fenofibric acid, a metabolite of fenofibrate ester, had no effects on AMPK phosphorylation, PEPCK gene expression, or glucose production in H4IIE cells. Fenofibrate-treated mice exhibited increases in AMPK phosphorylation and a decrease in PEPCK expression in the liver but not in skeletal muscles, suggesting that unmetabolized fenofibrate accumulated and affected AMPK only in the liver. Significance These results demonstrate that fenofibrate inhibits PEPCK gene expression and hepatic glucose production in the liver via AMPK activation, even though the metabolite loses its effects on AMPK and does not work in vivo in myocytes. This novel feature of fenofibrate may provide additional benefit for the treatment of patients with disorders of both lipid and glucose metabolism.