Combination treatment with statins and bezafibrate induces myotoxicity via inhibition of geranylgeranyl pyrophosphate biosynthesis and Rho activation in L6 myoblasts and myotube cells.

Statins and fibrates are frequently used to treat hyperlipidemia; however, these drugs may have adverse effects such as rhabdomyolysis. The incidence of rhabdomyolysis due to fibrates and statins is low (0.0028-0.0096%) when administered as monotherapy, however it increases to 0.015-0.021% when the drugs are used in combination. The mechanism underlying myotoxicity induced by the combination of statins and fibrates is yet unclear. Here, we investigated the mechanisms underlying induced myotoxicity in rat myoblasts L6 and differentiated L6 cells (myotubes) using a combination of statins and fibrates. We found that cell death induced by a combination of fluvastatin or simvastatin with bezafibrate or fenofibrate in L6 myoblasts and myotubes was mediated by inhibition of geranylgeranyl pyrophosphate (GGPP) production. Additionally, the drug combination inhibited Rho activation in L6 myoblasts and myotube cells. In L6 myoblasts, the combination of statins and bezafibrate enhanced p27 expression and induced G1 arrest and apoptosis. Furthermore, combined treatment suppressed Akt activation and enhanced Bim expression in L6 myotubes but did not affect extracellular regulated protein kinase 1/2 activation. These results suggested that combined administration of statins and fibrates induced death of L6 myoblasts and myotube cells by inhibiting GGPP biosynthesis and Rho pathway activation. Supplementation with GGPP may be therapeutically beneficial for preventing myotoxicity associated with combined statin and fibrates treatment.