Characterization of the molecular mechanism of the bone-anabolic activity of carfilzomib in multiple myeloma

• Published in: PloS one 2013-09, Vol.8 (9), p.e74191-e74191
• Main Authors: Hu, Bo, Chen, Yu, Usmani, Saad Z, Ye, Shiqiao, Qiang, Wei, Papanikolaou, Xenofon, Heuck, Christoph J, Yaccoby, Shmuel, Williams, Bart O, Van Rhee, Frits, Barlogie, Bart, Epstein, Joshua, Qiang, Ya-Wei
• Format: Article
• Language: English
• Subjects: Alkaline phosphatase; Analysis; beta Catenin - genetics; beta Catenin - metabolism; Biocompatibility; Biomedical materials; Bone diseases; Bone marrow; Calcium; Cancer; Cell cycle; Cell differentiation; Cell Differentiation - drug effects; Cells, Cultured; Differentiation (biology); Endocrinology; Frizzled protein; Gene expression; Gene regulation; Hepatocyte nuclear factor 1; Humans; Immunoblotting; Immunofluorescence; Kinases; Ligands; LRP5 protein; Mesenchymal stem cells; Mesenchymal Stromal Cells - cytology; Mesenchymal Stromal Cells - drug effects; Mesenchymal Stromal Cells - metabolism; Mesenchyme; Mineralization; Multiple myeloma; Multiple Myeloma - drug therapy; Multiple Myeloma - metabolism; Nuclear transport; Oligopeptides - therapeutic use; Osteoblastogenesis; Osteoblasts; Osteoprogenitor cells; Patients; Phosphatases; Proteasomes; Protein transport; Receptors; Review boards; Signal Transduction - drug effects; Signal Transduction - genetics; Signaling; Stem cells; Studies; Tcf protein; Transcription; Translocation; Wnt protein; β-Catenin
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0074191

Carfilzomib, the next generation of proteasome inhibitor, may increase osteoblast-related markers in patients with multiple myeloma, but the molecular mechanism of its effect on mesenchymal stem cell differentiation to osteoblasts remains unknown. Herein, we demonstrated that carfilzomib significantly promoted mesenchymal stem cell differentiation into osteoblasts. In osteoprogenitor cells and primary mesenchymal stem cells from patients with myeloma, carfilzomib induced increases in alkaline phosphatase activity, matrix mineralization, and calcium deposition via Wnt-independent activation of β-catenin/TCF signaling. Using affinity pull-down assays with immunoblotting analysis and immunofluorescence, we found that carfilzomib induced stabilization of both free and active forms of β-catenin in a time- and dose-dependent manner that was not associated with β-catenin transcriptional regulation. Nuclear translocation of β-catenin protein was associated with TCF transcriptional activity that was independent of the effects of GSK3β-activation and of signaling induced by 19 Wnt ligands, 10 Frizzled receptors, and LRP5/6 co-receptors. Blocking activation of β-catenin/TCF signaling by dominant negative TCF1 or TCF4 attenuated carfilzomib-induced matrix mineralization. Thus, carfilzomib induced osteoblast differentiation via Wnt-independent activation of the β-catenin/TCF pathway. These results provide a novel molecular mechanism critical to understanding the anabolic role of carfilzomib on myeloma-induced bone disease.