Statins inhibit osteoblast migration by inhibiting Rac-Akt signaling

Cell migration is a key event in repair and remodeling of skeletal tissues, but the mechanism of osteoblast migration has not been resolved. Statins, which are inhibitors of 3-hydroxy-3-methylglutaryl CoA reductase, increase bone. However, the effect of statins on osteoblast migration remains to be clarified. We investigated the effect of fluvastatin and mevastatin on platelet-derived growth factor (PDGF)-induced migration of osteoblastic MC3T3-E1 cells. PDGF promoted osteoblast migration, while the statins inhibited PDGF-induced migration, and mevalonate and geranylgeranylpyrophosphate but not farnesylpyrophosphate abolished the effect of statins. Dominant-negative Rac severely inhibited PDGF-induced osteoblast migration and reduced Akt phosphorylation. Further, fluvastatin reduced Akt phosphorylation and dominant-negative Akt inhibited PDGF-induced osteoblast migration. These results demonstrate that statins inhibit PDGF-induced osteoblast migration and Rac-Akt signaling plays an important role in the osteoblast migration, and suggest that statins restrain Rac function by inhibiting geranylgeranylation of Rac, which leads to the reduction in Akt activation and osteoblast migration.