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Osteoclast Precursor Cells (osteoclast + precursor_cell)
Selected AbstractsImatinib mesylate suppresses bone metastases of breast cancer by inhibiting osteoclasts through the blockade of c-Fms signalsINTERNATIONAL JOURNAL OF CANCER, Issue 1 2009Toru Hiraga Abstract Imatinib mesylate (imatinib) is a potent and selective inhibitor of the tyrosine kinases, Bcr-Abl, c-Kit and platelet-derived growth factor receptors (PDGFRs). Recently, it has been reported that imatinib also targets the macrophage colony-stimulating factor (M-CSF) receptor c-Fms. M-CSF signals are essential for the differentiation of osteoclasts. Bone metastases of breast cancer are frequently associated with osteoclastic bone destruction. Furthermore, several lines of evidence suggest that osteoclasts play central roles in the development and progression of bone metastases. Thus, in the present study, we examined the effects of imatinib on bone metastases of breast cancer. Coimmunoprecipitation assays showed that imatinib inhibited the M-CSF-induced phosphorylation of c-Fms in osteoclast precursor cells as well as the PDGF-induced PDGFR phosphorylation in MDA-MB-231 human breast cancer cells. Imatinib also markedly reduced osteoclast formation in vitro. In contrast, those concentrations of imatinib did not affect osteoblast differentiation. We then examined the effects of imatinib on bone metastases of MDA-MB-231 cells in a nude mouse model. Radiographic and histomorphometric analyses demonstrated that imatinib significantly decreased bone metastases associated with the reduced number of osteoclasts. In support of the notion that the inhibition of c-Fms acts to suppress the development of bone metastases, we found that a specific inhibitor of c-Fms Ki20227 also decreased bone metastases. In conclusion, these results collectively suggest that imatinib reduced bone metastases, at least in part, by inhibiting osteoclastic bone destruction through the blockade of c-Fms signals. Our results also suggest that imatinib may have a protective effect against cancer treatment-induced bone loss. © 2008 Wiley-Liss, Inc. [source] Tumor necrosis factor-, mediates polymethylmethacrylate particle-induced NF-,B activation in osteoclast precursor cellsJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 2 2002John C. Clohisy Tumor necrosis factor-, (TNF) is a potent osteoclastogenic cytokine that has a fundamental role in the pathogenesis of implant particle-induced osteolysis. The nuclear transcription factor NF-,B mediates TNF signaling and this transcription complex is necessary for osteoclastogenesis. Because polymethylmethacrylate (PMMA) particles cause osteolysis, we reasoned the PMMA would induce NF-,B activation. In fact, we find that exposure of osteoclast precursors, in the form of colony stimulating factor-1 (CSF-1) dependent murine bone marrow macrophages, to PMMA particles prompts nuclear translocation and activation of NF-,B. Supershift assays confirm the presence of the p50 and p65 NF-,B subunits in the activated transcription factor. Particle-induced NF-,B activation is equal in both wild type and LPS- hyporesponsive cells indicating that the phenomenon does not represent endotoxin contamination. A soluble, competitive inhibitor of TNF (huTNF:Fc) dampens particle-directed NF-,B activation and this response is also abrogated in TNF,/, osteoclast precursors. Thus, PMMA particle activation of NF-,B is a secondary event resulting from enhanced TNF expression and is independent of LPS contamination. © 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source] Low-energy laser stimulates tooth movement velocity via expression of RANK and RANKLORTHODONTICS & CRANIOFACIAL RESEARCH, Issue 3 2008S Fujita Structured Abstract Authors,,, Fujita S, Yamaguchi M, Utsunomiya T, Yamamoto H, Kasai K Objective,,, Recent studies have demonstrated that low-energy laser irradiation stimulates bone formation in vitro and in vivo. However, very little is known about the effects of laser irradiation on osteoclastogenesis. The receptor activator of the nuclear factor- kB (RANK),/,RANK ligand (RANKL),/,osteoprotegerin (OPG) system is essential and sufficient for osteoclastogenesis. The present study was designed to examine the effects of low-energy laser irradiation on expressions of RANK, RANKL, and OPG during experimental tooth movement. Design,,, To induce experimental tooth movement in rats, 10 g of orthodontic force was applied to the molars. Next, a Ga,Al,As diode laser was used to irradiate the area around the moved tooth and the amount of tooth movement was measured for 7 days. Immunohistochemical staining with RANK, RANKL, and OPG was performed. Real time PCR was also performed to elucidate the expression of RANK in irradiated rat osteoclast precursor cells in vitro. Results,,, In the irradiation group, the amount of tooth movement was significantly greater than in the non-irradiation group by the end of the experimental period. Cells that showed positive immunoreactions to the primary antibodies of RANKL and RANK were significantly increased in the irradiation group on day 2 and 3, compared with the non-irradiation group. In contrast, the expression of OPG was not changed. Further, RANK expression in osteoclast precursor cells was detected at an early stage (day 2 and 3) in the irradiation group. Conclusion,,, These findings suggest that low-energy laser irradiation stimulates the velocity of tooth movement via induction of RANK and RANKL. [source] | ||||||||||