Wnt signaling as a therapeutic target for bone diseases

Background: There is a need to develop new bone anabolic agents because current bone regeneration regimens have limitations. The Wingless-type MMTV integration site (Wnt) pathway has emerged as a regulator of bone formation and regeneration. Objective: To review the molecular basis for Wnt pathway modulation and discuss strategies that target it and improve bone mass. Methods: Data in peer-reviewed reports and meeting abstracts are discussed. Results/conclusions: Neutralizing inhibitors of Wnt signaling have emerged as promising strategies. Small-molecule inhibitors of glycogen synthase kinase 3β increase bone mass, lower adiposity and reduce fracture risk. Neutralizing antibodies to Dickkopf 1, secreted Frizzled-related protein 1 and sclerostin produce similar outcomes in animal models. These drugs are exciting breakthroughs but are not without risks. The challenges include tissue-specific targeting and consequently, long-term safety.