Anti-IFN-γ Antibody Promotes Osteoclastogenesis in Human Bone Marrow Monocyte-Derived Macrophages Co-Cultured with Tuberculosis-Activated Th1 Cells

Background/Aims: Tuberculosis induces bone loss and activates Th1 cells that play an important role in the host defense of Bacille Calmette-Guérin tuberculosis vaccine. However, the role of tuberculosis-activated Th1 cells in differentiation of osteoclast precursors to osteoclasts is unclear. As secretion of IFN-γ in Th1 cells is induced by tuberculosis, we aimed to investigate the role of anti-IFN-γ antibody on the differentiation and activation of osteoclasts in bone marrow monocyte-derived macrophages (BMMs). Methods: BMMs were isolated and co-cultured with CD4+T helper 1 cells (Th1 cells), pretreated with anti-IFN-γ antibody. Then, cell proliferation, expression and release of cytokines, formation of actin ring, differentiation of osteoclasts and bone resorption function were measured by CCK8 assay, qRT-PCR/Western blot/flow cytometry, ELISA, immunofluorescence, tartrate-resistant acidic phosphatase (TRAP) staining and bone absorbance assay, respectively. Results: Anti-IFN-γ antibody inhibited the cell viability of BMMs, and induced the expressions of RANKL, TNF-α, NF-κB and TRAF6 in BMMs. In addition, it led to increased expression levels of RANK on cell surfaces, and increased production of RANKL, TNF-α, MCP-1 and SDF-1. Anti-IFN-γ antibody also induced the expression of osteoclast differentiation factor and actin ring formation, but inhibited the expression of osteoprotegerin. TRAP staining and bone resorption assays showed that anti-IFN-γ antibody induced an increase in osteoclast formation and bone resorption. Conclusion: The anti-IFN-γ antibody induced osteoclast formation, and is probably mediated by RANKL-induced activation of NF-κB, that induces TRAF6 in the RANKL-RANK signaling pathway. Our data suggest an inhibitory role for IFN-γ in osteoclast formation induced by tuberculosis.

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4-Acetylantroquinonol B Inhibits Osteoclastogenesis by Inhibiting the Autophagy Pathway in a Simulated Microgravity Model

International Journal of Molecular Sciences ◽

10.3390/ijms21186971 ◽

2020 ◽

Vol 21 (18) ◽

pp. 6971

Author(s):

Chia-Hsin Wu ◽

Ching-Huei Ou ◽

I-Chuan Yen ◽

Shih-Yu Lee

Keyword(s):

Bone Resorption ◽

Transmembrane Protein ◽

Osteoclast Differentiation ◽

Osteoclast Formation ◽

Tartrate Resistant Acid Phosphatase ◽

Nuclear Factor ◽

Actin Ring ◽

Activated T Cells ◽

Cycle Arrest ◽

Trap Staining

Astronauts suffer from 1–2% bone loss per month during space missions. Targeting osteoclast differentiation has been regarded as a promising strategy to prevent osteoporosis in microgravity (μXg). 4-acetylantroquinonol B (4-AAQB), a ubiquinone from Antrodia cinnamomea, has shown anti-inflammatory and anti-hepatoma activities. However, the effect of 4-AAQB on μXg-induced osteoclastogenesis remains unclear. In this study, we aimed to explore the mechanistic impact of 4-AAQB on osteoclast formation under μXg conditions. The monocyte/macrophage-like cell line RAW264.7 was exposed to simulated μXg (Rotary Cell Culture System; Synthecon, Houston, TX, USA) for 24 h and then treated with 4-AAQB or alendronate (ALN) and osteoclast differentiation factor receptor activator of nuclear factor kappa-B ligand (RANKL). Osteoclastogenesis, bone resorption activity, and osteoclast differentiation-related signaling pathways were analyzed using tartrate-resistant acid phosphatase (TRAP) staining, actin ring fluorescent staining, bone resorption, and western blotting assays. Based on the results of TRAP staining, actin ring staining, and bone resorption assays, we found that 4-AAQB significantly inhibited μXg-induced osteoclast differentiation. The critical regulators of osteoclast differentiation, including nuclear factor of activated T-cells cytoplasmic 1 (NFATc1), c-Fos, and dendritic cell-specific transmembrane protein (DC-STAMP), were consistently decreased. Meanwhile, osteoclast apoptosis and cell cycle arrest were also observed along with autophagy suppression. Interestingly, the autophagy inhibitors 3-methyladenine (3-MA) and chloroquine (CQ) showed similar effects to 4-AAQB. In conclusion, we suggest that 4-AAQB may serve as a potential agent against μXg-induced osteoclast formation.

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Inhibition of intravacuolar acidification by antisense RNA decreases osteoclast differentiation and bone resorption in vitro

Journal of Cell Science ◽

10.1242/jcs.112.21.3657 ◽

1999 ◽

Vol 112 (21) ◽

pp. 3657-3666 ◽

Cited By ~ 1

Author(s):

T. Laitala-Leinonen ◽

C. Lowik ◽

S. Papapoulos ◽

H.K. Vaananen

Keyword(s):

Bone Marrow ◽

Bone Resorption ◽

Antisense Rna ◽

Osteoclast Differentiation ◽

Osteoclast Formation ◽

Gm Csf ◽

Monocytes And Macrophages ◽

Marrow Cultures ◽

Rat Bone

The role of proton transport and production in osteoclast differentiation was studied in vitro by inhibiting the transcription/translation of carbonic anhydrase II (CA II) and vacuolar H(+)-ATPase (V-ATPase) by antisense RNA molecules. Antisense RNAs targeted against CA II, or the 16 kDa or 60 kDa subunit of V-ATPase were used to block the expression of the specific proteins. A significant decrease in bone resorption rate and TRAP-positive osteoclast number was seen in rat bone marrow cultures and fetal mouse metacarpal cultures after antisense treatment. Intravacuolar acidification in rat bone marrow cells was also significantly decreased after antisense treatment. The CA II antisense RNA increased the number of TRAP-positive mononuclear cells, suggesting inhibition of osteoclast precursor fusion. Antisense molecules decreased the number of monocytes and macrophages, but increased the number of granulocytes in marrow cultures. GM-CSF, IL-3 and IL-6 were used to stimulate haematopoietic stem cell differentiation. The 16 kDa V-ATPase antisense RNA abolished the stimulatory effect of GM-CSF, IL-3 and IL-6 on TRAP-positive osteoclast formation, but did not affect the formation of monocytes and macrophages after IL-3 treatment, or the formation of granulocytes after IL-6 treatment. These results suggest that CA II and V-ATPase are needed, not only for the actual resorption, but also for osteoclast formation in vitro.

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Tumor Necrosis Factor α Stimulates Osteoclast Differentiation by a Mechanism Independent of the Odf/Rankl–Rank Interaction

Journal of Experimental Medicine ◽

10.1084/jem.191.2.275 ◽

2000 ◽

Vol 191 (2) ◽

pp. 275-286 ◽

Cited By ~ 891

Author(s):

Kanichiro Kobayashi ◽

Naoyuki Takahashi ◽

Eijiro Jimi ◽

Nobuyuki Udagawa ◽

Masamichi Takami ◽

...

Keyword(s):

Bone Marrow ◽

Tumor Necrosis Factor ◽

Tumor Necrosis ◽

Tumor Necrosis Factor Α ◽

Osteoclast Differentiation ◽

Osteoclast Formation ◽

Fab Fragment ◽

Tnf Α ◽

Factor Α ◽

Necrosis Factor

Osteoclast differentiation factor (ODF, also called RANKL/TRANCE/OPGL) stimulates the differentiation of osteoclast progenitors of the monocyte/macrophage lineage into osteoclasts in the presence of macrophage colony-stimulating factor (M-CSF, also called CSF-1). When mouse bone marrow cells were cultured with M-CSF, M-CSF–dependent bone marrow macrophages (M-BMMφ) appeared within 3 d. Tartrate-resistant acid phosphatase–positive osteoclasts were also formed when M-BMMφ were further cultured for 3 d with mouse tumor necrosis factor α (TNF-α) in the presence of M-CSF. Osteoclast formation induced by TNF-α was inhibited by the addition of respective antibodies against TNF receptor 1 (TNFR1) or TNFR2, but not by osteoclastogenesis inhibitory factor (OCIF, also called OPG, a decoy receptor of ODF/RANKL), nor the Fab fragment of anti–RANK (ODF/RANKL receptor) antibody. Experiments using M-BMMφ prepared from TNFR1- or TNFR2-deficient mice showed that both TNFR1- and TNFR2-induced signals were important for osteoclast formation induced by TNF-α. Osteoclasts induced by TNF-α formed resorption pits on dentine slices only in the presence of IL-1α. These results demonstrate that TNF-α stimulates osteoclast differentiation in the presence of M-CSF through a mechanism independent of the ODF/RANKL–RANK system. TNF-α together with IL-1α may play an important role in bone resorption of inflammatory bone diseases.

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Hedgehog Inhibitors Suppress Osteoclastogenesis in In Vitro Cultures, and Deletion of Smo in Macrophage/Osteoclast Lineage Prevents Age-Related Bone Loss

International Journal of Molecular Sciences ◽

10.3390/ijms21082745 ◽

2020 ◽

Vol 21 (8) ◽

pp. 2745

Author(s):

Yukihiro Kohara ◽

Ryuma Haraguchi ◽

Riko Kitazawa ◽

Yuuki Imai ◽

Sohei Kitazawa

Keyword(s):

Bone Resorption ◽

Bone Loss ◽

Signaling Pathway ◽

Early Stage ◽

Osteoclast Differentiation ◽

Osteoclast Formation ◽

Age Related ◽

Hh Signaling

The functional role of the Hedgehog (Hh)-signaling pathway has been widely investigated in bone physiology/development. Previous studies have, however, focused primarily on Hh functions in bone formation, while its roles in bone resorption have not been fully elucidated. Here, we found that cyclopamine (smoothened (Smo) inhibitor), GANT-58 (GLI1 inhibitor), or GANT-61 (GLI1/2 inhibitor) significantly inhibited RANKL-induced osteoclast differentiation of bone marrow-derived macrophages. Although the inhibitory effects were exerted by cyclopamine or GANT-61 treatment during 0–48 h (early stage of osteoclast differentiation) or 48–96 h (late stage of osteoclast differentiation) after RANKL stimulation, GANT-58 suppressed osteoclast formation only during the early stage. These results suggest that the Smo-GLI1/2 axis mediates the whole process of osteoclastogenesis and that GLI1 activation is requisite only during early cellular events of osteoclastogenesis. Additionally, macrophage/osteoclast-specific deletion of Smo in mice was found to attenuate the aging phenotype characterized by trabecular low bone mass, suggesting that blockage of the Hh-signaling pathway in the osteoclast lineage plays a protective role against age-related bone loss. Our findings reveal a specific role of the Hh-signaling pathway in bone resorption and highlight that its inhibitors show potential as therapeutic agents that block osteoclast formation in the treatment of senile osteoporosis.

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Novel P38 MAP Kinase Inhibitor and Anti-P38 RNA Interference as Potential Therapeutic Approaches in Myelodysplastic Syndromes.

Blood ◽

10.1182/blood.v104.11.470.470 ◽

2004 ◽

Vol 104 (11) ◽

pp. 470-470

Author(s):

Mani Mohindru ◽

Perry Pahanish ◽

Efstratios Katsoulidis ◽

Robert Collins ◽

Thomas Rogers ◽

...

Keyword(s):

Bone Marrow ◽

Map Kinase ◽

P38 Mapk ◽

Colony Formation ◽

P38 Map Kinase ◽

Hematopoietic Progenitors ◽

P38 Inhibitor ◽

Tnf Α ◽

Ifn Γ

Abstract Cytokines such as TNF α, IFN γ and others have been implicated in the pathogenesis of ineffective hematopoiesis in MDS and are thought to lead to the high rate of apoptosis in hematopoietic progenitors. The p38 Mitogen Activated Protein Kinase (MAPK) is an evolutionary conserved enzyme that is involved in many cellular processes including stress signaling. We have previously shown that the p38 MAP kinase is strongly activated by IFNs, TNF α, TGF β and other inhibitory cytokines in normal primary hematopoietic progenitors and plays an important role in the negative regulation of normal hematopoiesis. In the present study, we determined the role of the p38 MAPK in the pathogenesis of MDS evaluated its inhibition as a potential therapeutic strategy in this disease. p38 MAPK inhibition was achieved by the use of a novel p38 inhibitor - SD-282, a specific inhibitor of p38α MAP kinase. SD-282 performs very similarly in animal and cell models to a p38 inhibitor now in the clinic. We also transfected primary hematopoietic cells with flurescent labeled siRNAs against p38 and successfully downregulated the levels of the protein. Using these approaches, we demonstrate that pharmacological inhibition of the p38 MAPK can reverse the growth inhibitory effects of TNF α and IFN γ on erythroid and myeloid colony formation. This reversal of TNF α mediated inhibition correlates with significant reduction of apoptosis seen in human hematopoeitic progenitors pretreated with p38 inhibitor SD-282. Having established the importance of p38 MAPK in cytokine mediated inhibition of normal hematopoiesis, we performed colony forming assays with bone marrow CD34+ cells from 8 patients with MDS in the presence of either pharmacologic or siRNA based inhibitors of p38. All patients had refractory cytopenias with multilineage dysplasia. Our data indicates that SD-282 treatment strongly enhances both erythroid and myeloid colony formation in MDS CD34+ bone marrow cells in vitro. This increase was not observed when these progenitors were grown in the presence of negative controls - SB 202474 and the MEK inhibitor PD 98059. Similarly, an increase in hematopoietic colony formation, though of a lesser magnitude was seen when MDS bone marrow progenitors were transfected with siRNAs against p38 MAPK. To further determine the role of cytokines in the pathogenesis of MDS, we also used bone marrow derived sera from the same MDS patients. Our studies show exposure to patient derived sera led to the phosphorylation/activation of p38 MAPK in normal hematopoietic progenitors when compared to sera from healthy volunteers. Our studies also demonstrate that bone marrow derived sera from MDS patients can inhibit erythroid and myeloid colony formation of normal hematopoietic progenitors. This inhibition can be reversed by blocking p38 MAPK using SD-282, other p38 inhibitors and siRNAs. This finding confirms the role of marrow cytokine /serum factors in the ineffective hematopoiesis seen in MDS and suggests the importance of p38 MAPK activation in this phenomenon. Thus our studies show the p38 MAPK may be a common effector of inhibitory cytokine signaling in normal and MDS hematopoietic cells. These results provide a strong rationale for using p38 inhibition as a novel treatment strategy for MDS. Supported by Harris Methodist Foundation Grant, VISN-17 New Investigator Grant and VA Research Corp Grant to AV.

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Thalidomide Derivative CC-4047 Inhibits Osteoclast Formation by down Regulation of PU.1.

Blood ◽

10.1182/blood.v106.11.629.629 ◽

2005 ◽

Vol 106 (11) ◽

pp. 629-629 ◽

Cited By ~ 1

Author(s):

Suzanne Lentzsch ◽

Gulsum Anderson ◽

Noriyoshi Kurihara ◽

Tadashi Honjo ◽

Judith Anderson ◽

...

Keyword(s):

Bone Marrow ◽

Bone Resorption ◽

Bone Marrow Cells ◽

Osteoclast Differentiation ◽

Inhibitory Effect ◽

Osteoclast Formation ◽

Early Event ◽

Down Regulation ◽

Bone Marrow Cultures

Abstract CC-4047 (Actimid) is an immunomodulatory analog of thalidomide that has stronger anti-myeloma and anti-angiogenic activity than thalidomide, but its effects on human osteoclast lineage are unknown. Early osteoclast progenitors are of hematopoietic origin and progressively differentiate into mature bone resorbing multinucleated osteoclasts. We investigated the effects of CC-4047 and thalidomide on human osteoclastogenesis, using in vitro receptor activator of NFκ-B ligand/M-CSF stimulated culture system of bone marrow cells. Three weeks of treatment of primary bone marrow cultures with 100 μM CC-4047 decreased osteoclast formation accompanied by complete inhibition of bone resorption. Interestingly, osteoclast formation was also inhibited when cultures were treated with CC-4047 only for the first week (90% inhibition). In contrast, inhibitory effect was greatly diminished when the drug was given for only the last week (25% inhibition), indicating that inhibition of osteoclast formation is an early event. The inhibitory effect of CC-4047 on osteoclastogenesis was not induced by cell death, but by a shift of lineage commitment to granulocyte-CFU at the expense of GM-CFU that are osteoclast progenitors. Further studies revealed that this shift is mediated through down regulation of the transcription factor PU.1, which is critical for early osteoclast formation. In contrast to CC-4047, thalidomide was a significantly less potent inhibitor of osteoclast formation and bone resorption. These results provide the first evidence that CC-4047 blocks osteoclast differentiation at the early phase of osteoclastogenesis. Therefore, CC-4047 might be a valuable drug targeting both the tumor and osteoclastic activity in patients with multiple myeloma and potentially other diseases associated with the development of osteolytic lesions.

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Brain-Derived Neurotrophic Factor Is a Potential Osteoclast Stimulatory Factor In Multiple Myeloma

Blood ◽

10.1182/blood.v116.21.1917.1917 ◽

2010 ◽

Vol 116 (21) ◽

pp. 1917-1917

Author(s):

Chun-Yan Sun ◽

Yu Hu ◽

Xiao-Mei She ◽

You Qin ◽

Lu Zhang ◽

...

Keyword(s):

Multiple Myeloma ◽

Bone Marrow ◽

Bone Resorption ◽

Bone Disease ◽

Neurotrophic Factor ◽

Brain Derived Neurotrophic Factor ◽

Osteoclast Formation ◽

Bone Lesions ◽

Bone Marrow Plasma

Abstract Abstract 1917 Background and Objective: Multiple myeloma (MM) is characterized by accumulation of monoclonal plasma cells in the bone marrow and progression of lytic bone lesions. The mechanisms of enhanced bone resorption in patients with myeloma are not fully defined. We have previously identified the role of brain-derived neurotrophic factor (BDNF) in proliferation and migration of MM cells. In the present study, we investigated whether BDNF was present in marrow from patients with MM and possibly involved in MM cell-induced osteolysis. Methods and Results: Levels of bone marrow plasma BDNF was measured by ELISA in a cohort of individuals with MM and controls. The concentration of BDNF was found to be significantly elevated in patients with MM (879 ± 93) pg/ml when compared with bone marrow plasma derived from normal control subjects (186 ± 52) pg/ml (p < 0.001). Moreover, bone marrow plasma levels of BDNF positively correlated with plasma cell burden and extent of bone disease in MM patients. In osteoclast formation assay, bone marrow plasma from 31 of 37 patients with MM tested significantly stimulated the formation of osteoclast when compared to controls (61.8 ± 7 [mean ± SEM for the 31 patients] versus 25.2 ± 6 TRAP+ multinucleated cells/well [mean ± SEM for the 12 controls]; p < 0.01). The effect was significantly blocked by a neutralizing antibody to BDNF (p < 0.05), suggesting a critical role for BDNF in osteoclast activation. Furthermore, BDNF was found to dose-dependently increased the formation of multinucleated, TRAP+ osteoclast. The direct effects of recombinant BDNF on osteoclast formation and bone resorption support the potential role of BDNF in the MM bone disease. Using reverse-transcriptase polymerase chain reaction analysis and western blotting assay, we demonstrated that BDNF receptor TrkB was expressed by human osteoclast precursors and a Trk inhibitor K252a markedly inhibited osteoclast formation stimulated with BDNF. These data suggested that TrkB is the functional receptor mediating BDNF's effect on osteoclast formation. Finally, bone marrow plasma BDNF level positively correlated with macrophage inflammatory protein (MIP)-1α (r = 0.45, p < 0.005) and receptor activator of nuclear factor-κB ligand (RANKL) (r = 0.68, p < 0.0001), two major osteoclast stimulatory factors in MM. Conclusion: Taken together, our results demonstrate the ability of MM cells to secret BDNF correlates with the severity of osteoclastic bone resorption, and provide evidence that BDNF play a causal role in the development of MM bone lesions through TrkB receptor. Disclosures: No relevant conflicts of interest to declare.

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An Essential Role of Cytosolic Phospholipase A2α in Prostaglandin E2–mediated Bone Resorption Associated with Inflammation

Journal of Experimental Medicine ◽

10.1084/jem.20030015 ◽

2003 ◽

Vol 197 (10) ◽

pp. 1303-1310 ◽

Cited By ~ 124

Author(s):

Chisato Miyaura ◽

Masaki Inada ◽

Chiho Matsumoto ◽

Tomoyasu Ohshiba ◽

Naonori Uozumi ◽

...

Keyword(s):

Bone Marrow ◽

Bone Resorption ◽

Bone Loss ◽

Stromal Cells ◽

Osteoclast Formation ◽

Wild Type ◽

Cytosolic Phospholipase ◽

Cytosolic Phospholipase A2α ◽

Cox 2

Prostaglandin E (PGE)2 produced by osteoblasts acts as a potent stimulator of bone resorption. Inflammatory bone loss is accompanied by osteoclast formation induced by bone-resorbing cytokines, but the mechanism of PGE2 production and bone resorption in vivo is not fully understood. Using cytosolic phospholipase A2α (cPLA2α)-null mice, we examined the role of cPLA2α in PGE2 synthesis and bone resorption. In bone marrow cultures, interleukin (IL)-1 markedly stimulated PGE2 production and osteoclast formation in wild-type mice, but not in cPLA2α-null mice. Osteoblastic bone marrow stromal cells induced the expression of cyclooxygenase (COX)-2 and membrane-bound PGE2 synthase (mPGES) in response to IL-1 and lipopolysaccharide (LPS) to produce PGE2. Osteoblastic stromal cells collected from cPLA2α-null mice also induced the expression of COX-2 and mPGES by IL-1 and LPS, but could not produce PGE2 due to the lack of arachidonic acid release. LPS administration to wild-type mice reduced femoral bone mineral density by increased bone resorption. In cPLA2α-null mice, however, LPS-induced bone loss could not be observed at all. Here, we show that cPLA2α plays a key role in PGE production by osteoblasts and in osteoclastic bone resorption, and suggest a new approach to inflammatory bone disease by inhibiting cPLA2α.

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Autocrine Regulation of Osteoclast Formation and Bone Resorption by IL-1α and TNFα

Journal of Dental Research ◽

10.1177/00220345990780100601 ◽

1999 ◽

Vol 78 (10) ◽

pp. 1617-1623 ◽

Cited By ~ 38

Author(s):

N. Tani-Ishii ◽

A. Tsunoda ◽

T. Teranaka ◽

T. Umemoto

Keyword(s):

Bone Resorption ◽

Osteoclast Differentiation ◽

Osteoclast Formation ◽

Mouse Bone Marrow ◽

Multinucleated Cells ◽

Multinuclear Cells ◽

And Control

Bone resorption is regulated by the cytokines within marrow cells that mediate osteoclast formation and activation. IL-1 and TNF induce bone resorption by stimulating the production of osteoclast-like multinucleated cells and by increasing the bone-resorbing activity of formed osteoclasts. This study was designed to detect IL-1 and TNF in osteoclasts in vitro and to determine whether these cytokines up-regulate osteoclast differentiation and bone resorption. The production of IL-1α, -β, and TNFa, β in osteoclasts was examined immunohistochemically and by in situ hybridization. In the co-culture of C57BL/6N mouse bone marrow and MC3T3-G2/PA6 cells, a colony of osteoclasts formed, and IL-1α and TNFa were detected. However, IL-1β and TNF β were not detected. To investigate the role of IL-1α and TNFα from osteoclasts, we enumerated TRAP-positive cells and measured the resorption pit areas in the presence of antibodies against IL-1α and TNFα. The addition of antibodies against IL-1α and TNFα to the co-culture system decreased the number of TRAP-positive colonies at seven days after incubation (anti-IL-1α, 25.0 ± 2.3%; anti-TNFα, 41.7 ± 3.7%; anti-IL-1α + anti-TNFα, 40.5 ± 1.3%; and control, 100%), and the ratio of mononuclear to multinuclear cells had changed (anti-IL-1α, 90:10; anti-TNFα, 75:25; anti-IL-1α+ anti-TNFα, 88:12; and control, 60:40). The total pit areas per dentin slice also decreased with the addition of antibodies (anti-IL-1α, 28,828; anti-TNFα, 49,249; anti-IL-1α + anti-TNFα, 30,685; and control, 303,139 mm2). These results suggest that local production of IL-la and TNFα by osteoclasts is an important mechanism for regulating the osteoclast differentiation and bone resorptive process.

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Thalidomide derivative CC-4047 inhibits osteoclast formation by down-regulation of PU.1

Blood ◽

10.1182/blood-2005-08-3450 ◽

2006 ◽

Vol 107 (8) ◽

pp. 3098-3105 ◽

Cited By ~ 115

Author(s):

Gülsüm Anderson ◽

Margarete Gries ◽

Noriyoshi Kurihara ◽

Tadashi Honjo ◽

Judy Anderson ◽

...

Keyword(s):

Multiple Myeloma ◽

Bone Marrow ◽

Bone Resorption ◽

Marrow Cell ◽

Osteoclast Differentiation ◽

Osteoclast Formation ◽

Lineage Commitment ◽

Down Regulation ◽

Colony Forming Units ◽

Macrophage Colony

Abstract CC-4047, an immunomodulatory analog of thalidomide, inhibits multiple myeloma with unknown effects on the human osteoclast lineage. Early osteoclast progenitors are of hematopoietic origin and differentiate into mature bone resorbing multinucleated osteoclasts. We investigated the effects of CC-4047 and thalidomide on human osteoclastogenesis, using in vitro receptor activator of NFκ-B ligand/macrophage colony-stimulating factor–stimulated bone marrow cell cultures. Treating bone marrow cultures with CC-4047 for 3 weeks decreased osteoclast formation accompanied by complete inhibition of bone resorption. The inhibitory effect was similar when cultures were treated for 3 weeks or for only the first week (90% inhibition), indicating that CC-4047 inhibits early stages of osteoclast formation. Inhibition of osteoclastogenesis by CC-4047 was mediated by a shift of lineage commitment to granulocyte colony-forming units at the expense of granulocyte-macrophage colony-forming units. Further studies revealed that this shift in lineage commitment was mediated through down-regulation of PU.1. Treatment with thalidomide resulted in significantly less potent inhibition of osteoclast formation and bone resorption. These results provide evidence that CC-4047 blocks osteoclast differentiation during early phases of osteoclastogenesis. Therefore, CC-4047 might be a valuable drug for targeting both tumors and osteoclastic activity in patients with multiple myeloma and other diseases associated with osteolytic lesions.

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