Small molecule inhibitors of the Dishevelled‐ CXXC 5 interaction are new drug candidates for bone anabolic osteoporosis therapy

Abstract

Bone anabolic agents promoting bone formation and rebuilding damaged bones would ideally overcome the limitations of anti‐resorptive therapy, the current standard prescription for osteoporosis. However, the currently prescribed parathyroid hormone (PTH)‐based anabolic drugs present limitations and adverse effects including osteosarcoma during long‐term use. Also, the antibody‐based anabolic drugs that are currently being developed present the potential limits in clinical application typical of macromolecule drugs. We previously identified that CXXC5 is a negative feedback regulator of the Wnt/β‐catenin pathway via its interaction with Dishevelled (Dvl) and suggested the Dvl–CXXC5 interaction as a potential target for anabolic therapy of osteoporosis. Here, we screened small‐molecule inhibitors of the Dvl–CXXC5 interaction via a newly established in vitro assay system. The screened compounds were found to activate the Wnt/β‐catenin pathway and enhance osteoblast differentiation in primary osteoblasts. The bone anabolic effects of the compounds were shown using ex vivo‐cultured calvaria. Nuclear magnetic resonance (NMR) titration analysis confirmed interaction between Dvl PDZ domain and KY‐02061, a representative of the screened compounds. Oral administration of KY‐02327, one of 55 newly synthesized KY‐02061 analogs, successfully rescued bone loss in the ovariectomized (OVX) mouse model. In conclusion, small‐molecule inhibitors of the Dvl–CXXC5 interaction that block negative feedback regulation of Wnt/β‐catenin signaling are potential candidates for the development of bone anabolic anti‐osteoporosis drugs.

CXXC5: A novel regulator and coordinator of TGF‐β, BMP and Wnt signaling

“…In mice, CXXC5 knockout or competitive peptide‐mediated disruption of the CXXC5‐Dvl interaction restores Wnt signaling and accelerates hair regrowth and wound‐induced hair follicle neogenesis . Similarly, targeting the CXXC5‐Dvl interaction with small molecules has been suggested as a new therapeutic approach for the treatment of anabolic osteoporosis …”

“…85 Similarly, targeting the CXXC5-Dvl interaction with small molecules has been suggested as a new therapeutic approach for the treatment of anabolic osteoporosis. 86 First, although CXXC5 is capable of associating with unmethylated CpG islands via its CXXC domain and regulating the expression of certain genes, the specific genomic sites at which CXXC5 binds to in a given cell type or context remain to be determined. Fourth, targeting of CXXC5, for example through inhibition of its interaction with the Dvl protein using competitive peptides or small molecules, is emerging as a promising means of therapeutic intervention in animal models.…”

Modulating the wnt signaling pathway with small molecules

“…With NMR titration analysis, Kim et al . identified KY‐02061, along with an analog, KY‐02327, as potential candidates for the development of bone anabolic anti‐osteoporosis drugs . These molecules block the Dvl‐CXXC5 interaction that works as a negative feedback loop for the Wnt signaling pathway.…”

Cloning, Purification and NMR Studies on β-catenin C-terminal Domain

“…The structure of arm domain from murine β-catenin has been already known 2 and various biological studies using that domain have been conducted, but still little is known about both terminal domains. [3][4][5][6][7] The structure of arm domain and C-terminal region (138-781) of human β-catenin was also solved, but C-terminus was not observed in the crystal structure due to its flexibility. However, these terminal domains were suggested to regulate bindings of β-catenin and its binding partners.…”