A pterostilbene derivative suppresses osteoclastogenesis by regulating RANKL-mediated NFκB and MAPK signaling in RAW264.7 cells

Background: A dysfunctional osteoclast activity is often the cause of bone destructive diseases, such as osteoporosis, periodontitis, erosive arthritis, and cancer. The NF kappa B ligand (RANKL) has been identified as a major mediator of bone resorption. Agents that suppress RANKL signaling have the potential to inhibit bone resorption or osteoclastogenesis. The present study aimed to determine the effect of a pterostilbene derivative (PTERC-T) for suppressing RANKL or tumor cells-induced osteoclastogenesis in RAW264.7 murine macrophages. Methods: Cytotoxicity was measured by MIT assay and inhibitory effect on osteoclastogenesis was analyzed by counting the number of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells and measuring the expression levels of the osteoclast-specific genes. The reactive oxygen species (ROS) generation was detected by FACS. Further, signaling pathways were analyzed by immunofluorescence and immunoblot analyses. Results: PTERC-T suppressed the differentiation of monocytes to osteoclasts in a dose and time-dependent manner. The expression of osteoclast marker genes like TRAP, cathepsin K (CTSK), matrix metalloproteinase 9 (MMP9) and transcription factors c-Fos, and nuclear factor of activated T cells cytoplasmic I (NFATc1) were also diminished by PTERC-T. PTERC-T scavenged intracellular ROS generation within osteoclast precursors during RANKL-stimulated osteoclastogenesis. Mechanistically, PTERC-T abrogated the phosphorylation of MAPKs (ERIC and JNK) and inhibited RANKL-induced activation of NE kappa B by suppressing I kappa B alpha phosphorylation and preventing NE kappa B/p65 nuclear translocation. Conclusions: This study thus identifies PTERC-T as an inhibitor of osteoclast formation and provides evidence for its role in preventing osteoporosis and other bone related disorders. However, further studies are needed to establish its efficacy in vivo. (C) 2015 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Sp. z o.o. All rights reserved.