It is important to identify therapeutic compounds with no adverse effects for use in the chemotherapy of patients with bone-related diseases. The aim of this study was to identify a new compound that inhibits osteoclast differentiation and bone resorption. Herein, we examined the effects of 1',2'-dihydrorotenone on osteoclast differentiation and bone resorption in vitro and in vivo. 1',2'-dihydrorotenone inhibited receptor activator of NF-kappaB ligand (RANKL)-induced osteoclast differentiation of cultured bone marrow macrophages (BMMs) in a dose-dependent manner. However, 1',2'-dihydrorotenone did not exert cytotoxic effect on BMMs. 1',2'-dihydrorotenone suppressed the expression of c-fos and NFATc1 as well as osteoclast-specific genes in BMMs treated with RANKL. Treatment with RANKL inhibited the expression of inhibitors of differentiation/DNA binding (Id)1, 2, and 3; however, in the presence of 1',2'-dihydrorotenone, RANKL did not suppress the expression of Id1, 2, and 3. Furthermore, 1',2'-dihydrorotenone inhibited bone resorption and considerably attenuated the erosion of trabecular bone induced by lipopolysaccharide treatment. Taken together, these results suggest that 1',2'-dihydrorotenone has the potential to be applied in therapies for bone-related diseases.
Bone Marrow ; Bone Resorption ; Humans ; Macrophages ; Osteoclasts ; Receptor Activator of Nuclear Factor-kappa B ; Rotenone

The ameloblastoma is a common odontogenic tumor of the jaw bone and represents approximately 1% of tumor in the jaw. However, it might be able to infiltrate into the adjacent tissue, causing bony destruction and high recurrent rate. In this study, expression of RANKL and OPG in ameloblastoma in relation to age and gender of patient and recurrence, location of the lesion were examined through immunohistochemisry study. The RANKL and OPG antibody staining were used. The obtained result were as follow. 1. Positive immunoreactivity to RANKL/OPG in all specimens was found. 2. 1n recurrenc, location of ameloblastoma and age, gender of patients using immunohistochemical expression of RANKL. There was not significant difference. 3. 1n recurrence, location of ameloblastoma and age, gender of patients using immunohistochemical expression of OPG. There was not significant difference. In summary, it is suggested that activation of osteoclasts by RANKL is an important mechanism by which ameloblastomas cause bone destruction.
Ameloblastoma* ; Humans ; Jaw ; Odontogenic Tumors ; Osteoclasts ; Receptor Activator of Nuclear Factor-kappa B* ; Recurrence

<b>OBJECTIVEb>To investigate the expression of receptor activator of nuclear factor kappaB ligand (RANKL) and osteoprotegerin (OPG) in periapical cyst and periapical granuloma by comparison with the expression in the normal periodontal tissue as control, and to identify their functional mechanism in the bone destruction of periapical cyst and granuloma.

<b>METHODSb>20 periapical cyst tissues (cyst group), 20 periapical granuloma tissues (granuloma group), and 20 normal periodontal tissues (control group) were collected respectively. Immunohistochemical technology was performed to detect the expression of RANKL and OPG in above three groups.

<b>RESULTSb>In cyst group, granuloma group and control group, the expression of RANKL were 75.00 +/- 7.54, 68.40 +/- 6.74 and 29.40 +/- 2.46, respectively. The expression of OPG were 38.10 +/- 7.09, 47.65 +/- 13.85 and 58.60 +/- 5.88, respectively. The differences among the three groups were statistically significant (P<0.05). RANKL and OPG in cysts group were negatively correlated (r=-0.56, P=0.01) and were not correlated with granuloma and control group (P>0.05).

<b>CONCLUSIONb>RANKL and OPG play roles in the bone absorption of periapical disease. In periapical disease, abnormal expression of RANKL and OPG are detected, RANKL significantly increase, OPG decrease, bone absorption accelerate and osteolytic lesion are observed. In periapical cyst, the bone absorption is more active compared with periapical granuloma.

Humans ; Male ; Osteoprotegerin ; Periapical Granuloma ; RANK Ligand ; Radicular Cyst ; Receptor Activator of Nuclear Factor-kappa B

OBJECTIVES: To investigate the relationship between single nucleotide polymorphism (SNP)s in Wnt antagonist genes, and production of osteoprotegerin (OPG) and soluble receptor activator of NF-kappaB ligand (sRANKL) by whole blood cells after hormone therapy (HT) in postmenopausal Korean women. MATERIALS AND METHODS: The Dkk1 c.318A>G, Dkk2 c.437G>A, Dkk3 c.1003A>G polymorphisms and sFRP3 c.970C>G, sFRP4 c.958C>A, and c.1019G>A polymorphisms, and sFRP5 c.20G>C polymorphisms were analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), direct sequencing, and Taqman assay in 75 postmenopausal Korean women receiving estrogen-progestogen therapy. The production of OPG and sRANKL by lipopolysaccharide-stimulated whole blood cells (WBC) before and after HT of 6 months were also measured. RESULTS: Changes in the production of OPG and sRANKL by lipopolysaccharide-stimulated WBC, and in ratios of sRANKL(x1,000)/OPG after HT of 6 months were not different according to SNPs in Wnt signal pathway genes except Dkk1 c.318A>G SNP. The AA genotype of Dkk1 c.318A>G SNP showed significantly higher changes (p<0.05) in ratios of sRANKL(x1,000)/OPG compared to other genotypes. There were no significant differences in changes in the production of OPG and sRANKL, and in ratios of sRANKL(x1,000)/OPG among combined genotypes of sFRP4 c.958C>A, and c.1019G>A polymorphisms after HT. CONCLUSIONS: Dkk1 c.318A>G SNP are related with changes in ratios of sRANKL(x1,000)/OPG in terms of the production of OPG and sRANKL by lipopolysaccharide-stimulated whole blood cells after HT.
Blood Cells ; Female ; Genotype ; Humans ; NF-kappa B ; Osteoprotegerin ; Polymorphism, Single Nucleotide ; Receptor Activator of Nuclear Factor-kappa B ; Signal Transduction

Osteoclasts are multinucleated cells formed mainly on bone surfaces in response to cytokines by fusion of bone marrow-derived myeloid lineage precursors that circulate in the blood. Major advances in understanding of the molecular mechanisms regulating osteoclast formation and functions have been made in the past 20 years since the discovery that their formation requires nuclear factor-kappa B (NF-kappaB) signaling and that this is activated in response to the essential osteoclastogenic cytokine, receptor activator of NF-kappaB ligand (RANKL), which also controls osteoclast activation to resorb (degrade) bone. These studies have revealed that RANKL and some pro-inflammatory cytokines, including tumor necrosis factor, activate NF-kappaB and downstream signaling, including c-Fos and nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1), and inhibition of repressors of NFATc1 signaling, to positively regulate osteoclast formation and functions. However, these cytokines also activate NF-kappaB signaling that can limit osteoclast formation through the NF-kappaB signaling proteins, TRAF3 and p100, and the suppressors of c-Fos/NFATc1 signaling, IRF8, and RBP-J. This paper reviews current understanding of how NF-kappaB signaling is involved in the positive and negative regulation of cytokine-mediated osteoclast formation and activation.
Cytokines ; NF-kappa B ; NFATC Transcription Factors ; Osteoclasts ; RANK Ligand ; Receptor Activator of Nuclear Factor-kappa B ; TNF Receptor-Associated Factor 3 ; Tumor Necrosis Factor-alpha

<b>OBJECTIVEb>To detect the expression of osteoclast related factors, tumor necrosis factor-alpha (TNF-alpha), receptor activator of NF-kappaB ligand (RANKL) and tartrate-resistant acid phosphatase (TRAP), in the process of bone remodeling.

<b>METHODSb>8-week-old male C57BL/6J mice were employed in this study to detect the expression of osteoclast related factors by real time PCR.

<b>RESULTSb>TNF-alpha, RANKL and TRAP were up regulated in the process of bone remodeling, they reached the peak on day 2, 5 and 10 individually after injury.

<b>CONCLUSIONb>Osteoclast related factors also participate in bone remodeling, which depends on the delicate balance between bone formation and bone resorption.

Animals ; Bone Resorption ; Male ; Mice ; Mice, Inbred C57BL ; NF-kappa B ; Osteoclasts ; Osteogenesis ; RANK Ligand ; Receptor Activator of Nuclear Factor-kappa B ; Tumor Necrosis Factor-alpha

BACKGROUND AND OBJECTIVES: Bone resorption in middle ear cholesteatoma is mostly responsible for serious complications of the disease, but the pathogenesis of destruction due to bone resorption has not been fully elucidated, although osteoclast activation have been indicated in reports to have a major effect. We have investigated if the receptor activator of NF-kappaB ligand (RANKL), a cytokine that is arguably the most critical regulator of osteoclast differentiation and activation and its natural inhibitor, osteoprotegerin (OPG), may be important in the bone loss of cholesteatoma. Also, we evaluated the correlation of RANKL and OPG level with the extent of bone destruction. SUBJECTS AND METHOD: A real time RT-PCR was performed to determine and quantify the expression of RANKL and OPG mRNA in 13 cases of cholesteatoma and 8 cases of normal auditory canal skin. RESULT: 1) All cholestatoma and normal external auditory canal skin expressed both mRNA of RANKL and OPG 2) mRNA of RANKL in cholesteatoma were expressed significantly higher than normal external auditory canal skin (p<0.05). 3). The ratio of RANKL to OPG concentration was significantly higher in cholesteatoma than in the normal external auditory canal skin (p<0.05). 4) The ratio of RANKL to OPG was significantly correlated to the extent of bone destruction (p<0.05). CONCLUSION: These findings suggest the RANKL-OPG loop feedback system is defined in cholesteatoma. RANKL may play a role in the bone destruction of cholesteatoma. In particular, the balance in the ratio of RANKL to OPG is more important than RANKL.
Bone Resorption ; Cholesteatoma* ; Cholesteatoma, Middle Ear ; Ear Canal ; Osteoclasts ; Osteoprotegerin* ; Receptor Activator of Nuclear Factor-kappa B* ; RNA, Messenger ; Skin

OBJECTIVE: To explore the effect of advanced glycation end products (AGEs) on osteoclasts at different stages of differentiation. METHODS: Raw264.7 cells cultured were induced for osteoclastogenesis using RANKL, and the stages of differentiation of the osteoclasts were determined with TRAP staining. The cells were then randomly divided into control group, early-stage AGEs intervention group and late-stage AGEs intervention group. The viability of the cells after AGEs treatment was assessed using CCK-8 method. The cells were examined after the induction for osteoclastogenesis using TRAP staining, and the expression levels of RANK, NFATC-1, TRAF-6, TRAP and CTSK mRNAs were tested with RT-PCR; the expressions of CTSK and RANK proteins were detected using Western boltting. RESULTS: We defined the initial 3 days of induction as the early stage of differentiation and the time beyond 3 days as the late stage of differentiation of Raw264.7 cells. Intervention with AGEs at 100 mg/L produced no significant effects on the viability of the cells, but AGEs suppressed the cell proliferation at a concentration exceeding 100 mg/L. The number of osteolasts in the early- and late-stage intervention groups was greater than that in the control group, but the cell count differed significantly only between the early-stage intervention group and control group ( < 0.05). The gene expressions of RANK, NFATC-1, TRAF-6, TRAP and CTSK all increased after the application of AGEs in both the early and late stages of differentiation, but the changes were significant only in the early-stage intervention group ( < 0.05). The changes in CTSK and RANK protein expressions were consistent with their mRNA expressions. CONCLUSIONS AGEs can affect the differentiation of osteoclasts differently when applied at different stages, and intervention with AGEs at the early stage produces stronger effect to promote osteoclast differentiation than its application at a late stage.
Animals ; Bone Resorption ; Cell Differentiation ; Mice ; Osteoclasts ; RANK Ligand ; RAW 264.7 Cells ; Receptor Activator of Nuclear Factor-kappa B

Bone invasion by oral cancer is a common clinical problem, which affects the choice of treatment and predicts a poor prognosis. Unfortunately, the molecular mechanism of this phenomenon has not been fully elucidated. Current studies have revealed that oral cancer cells modulate the formation and function of osteoclasts through the expression of a series of signal molecules. Many signal pathways are involved in this process, of which receptor activator of nuclear factor-κB ligand/receptor activator of nuclear factor-κB/osteoprotegerin signaling pathway attracted much attention. In this review, we introduce recent progress in molecular mechanisms of bone invasion by oral cancer.
Bone Resorption ; Bone and Bones ; Humans ; Mouth Neoplasms ; Osteoclasts ; Osteoprotegerin ; RANK Ligand ; Receptor Activator of Nuclear Factor-kappa B

<b>OBJECTIVEb>To study mRNA expression of receptor activator nuclear factor kappa B ligand (RANKL) and its decoy receptor, osteoprotegerin (OPG) in peri-implant tissue during unloading period.

<b>METHODSb>An animal model of dental implant was established in 6 male Beagle dogs of 1-2 years old. Bone remodeling was tested at 3, 7, 15, 30, 60 and 90 days since the placement of implants. RANKL and OPG mRNA expression were quantified by real-time polymerase chain reaction (PCR). Then mandibular bones were taken out and the morphological changes were observed by X-ray, bone tissue was tested by immunohistochemistry stain.

<b>RESULTSb>The most prominent period of bone remodeling occurred at 7th day after the placement of implants. The expression of RANKL and OPG increased in a time-dependent manner in both soft and hard tissue. After 7 days they gradually decreased.

<b>CONCLUSIONb>RANKL and OPG can express in soft tissue, and the changing tendency is consistent with the change of bone remodeling, it indicates that RANKL and OPG play an important role in the bone remodeling.

Animals ; Bone Remodeling ; Bone and Bones ; Carrier Proteins ; Dogs ; Male ; NF-kappa B ; Osteoprotegerin ; RANK Ligand ; Receptor Activator of Nuclear Factor-kappa B