Strontium Ranelate Decreases Receptor Activator of Nuclear Factor- B Ligand-Induced Osteoclastic Differentiation In Vitro: Involvement of the Calcium-Sensing Receptor (original) (raw)
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Journal of Cellular and Molecular Medicine, 2009
Bone loss associated with aging, oestrogen deficiency, immobilization or glucocorticoid treatment is characterized by insufficient bone formation relative to resorption, resulting in negative bone balance, alterations of bone mass and increased incidence of fractures [1, 2]. The available anti-osteoporotic drugs act by decreasing bone resorption or promoting bone formation, thereby resulting in increased bone mass and reduced fracture incidence in patients with osteoporosis [2]. The di-strontium salt strontium ranelate is a new anti-osteoporotic drug. In postmenopausal osteoporotic women, strontium ranelate (2 g/day) was found to reduce the risk of vertebral fracture, non-vertebral fracture and hip fracture over 3 years [3,4]. Strontium ranelate was reported to act by inhibiting bone resorption and promoting bone formation [5], thereby inducing a positive bone balance in experimental osteopenic models [6, 7] and in patients with postmenopausal osteoporosis [3-5, 8]. Previous studies indicate that strontium ranelate may act on osteoblasts to promote cell activity and differentiation [9-12]. Notably, others and we showed that strontium ranelate can activate cell replication in rodent calvaria osteoblasts, resulting in stimulation of collagen synthesis [9,13]. However, the cellular mechanisms involved in the effects of strontium ranelate in osteoblasts are not fully understood. One attractive hypothesis Calcium sensing receptor-dependent and receptor-independent activation of osteoblast replication and survival by strontium ranelate
Osteoporosis International, 2009
The effect of strontium ranelate (SR) on human osteoblast differentiation was tested. SR induced osteoblastic proliferation, in vitro mineralization, and increased the expression of osteocyte markers. SR also elicited an osteoprotegerin (OPG) secretory response. We conclude that SR promotes the osteoblast maturation and osteocyte differentiation while promoting an additional antiresorptive effect. Introduction SR is a new treatment for osteoporosis that reduces the risk of hip and vertebral fractures in postmenopausal women. This study sought to investigate the extent, to which SR modulates human osteoblast differentiation. Methods Adult human primary osteoblasts (NHBC) were exposed to SR under mineralizing conditions in long-term cultures. Osteoblast differentiation status was investigated by cell-surface phenotypic analysis. Expression of genes associated with osteoblast/osteocyte differentiation was examined using real-time RT-PCR. Secreted OPG was assayed by enzyme-linked immunosorbent assay.
Osteoblasts play key roles in the mechanisms of action of strontium ranelate
Background and purpose: Strontium ranelate reduces fracture risk in postmenopausal women with osteoporosis. Evidence from non-clinical studies and analyses of bone markers in phase III trials indicate that this is due to an increase in osteoblast formation and a decrease of osteoclastic resorption. The aim of this work was to investigate, in human cells, the mechanisms by which strontium ranelate is able to influence the activities of osteoblasts and osteoclasts. Experimental approach: Human primary osteoblasts were used to examine effects of strontium ranelate on replication (thymidine incorporation), differentiation (Runx2 and alkaline phosphatase) and cell survival (cell counts and caspase activity). Osteoprotegerin (OPG) was measured by quantitative reverse transcription PCR (qRT-PCR) and ELISA and receptor activator of NFkB ligand (RANKL) by qRT-PCR and Western blot. As strontium ranelate has been proposed as an agonist of the calcium-sensing receptor (CaSR), the involvement of CaSR in the effects of strontium ranelate on OPG and RANKL expression, and cell replication was examined using siRNA. Key results: Strontium ranelate increased mRNA and protein levels of OPG and suppressed those of RANKL. Strontium ranelate also stimulated osteoblast replication and differentiation and increased cell survival under stress. Knocking down CaSR suppressed strontium ranelate-induced stimulation of OPG mRNA, reduction of RANKL mRNA, and increase in replication, indicating the involvement of CaSR in these responses. Conclusions and implications: Our results demonstrate that osteoblasts play a key role in the mechanism of action of the anti-fracture agent, strontium ranelate by mediating both its anabolic and anti-resorptive actions, at least in part, via activation of CaSR.
European journal of pharmacology, 2013
Accumulation of advanced glycation endproducts (AGEs) in bone tissue occurs in ageing and in Diabetes mellitus, and is partly responsible for the increased risk of low-stress bone fractures observed in these conditions. In this study we evaluated whether the anti-osteoporotic agent strontium ranelate can prevent the deleterious effects of AGEs on bone cells, and possible mechanisms of action involved. Using mouse MC3T3E1 osteoblastic cells in culture we evaluated the effects of 0.1 mM strontium ranelate and/or 100 mg/ml AGEs-modified bovine serum albumin (AGEs-BSA) on cell proliferation, osteogenic differentiation and pro-inflammatory cytokine production. We found that AGEs-BSA alone decreased osteoblastic proliferation and differentiation (P o 0.01) while increasing IL-1b and TNFa production (P o0.01). On its own, strontium ranelate induced opposite effects: an increase in osteoblast proliferation and differentiation (P o 0.01) and a decrease in cytokine secretion (P o 0.01). Additionally, strontium ranelate prevented the inhibitory and pro-inflammatory actions of AGEs-BSA on osteoblastic cells (P o 0.01). These effects of strontium ranelate were blocked by co-incubation with either the MAPK inhibitor PD98059, or the calcium channel blocker nifedipine. We also evaluated by Western blotting the activation status of ERK (a MAPK) and b-catenin. Activation of both signaling pathways was decreased by AGEs treatment, and this inhibitory effect was prevented if AGEs were co-incubated with strontium ranelate (P o0.01). On its own, strontium ranelate increased both pERK and activated b-catenin levels. In conclusion, this study demonstrates that strontium ranelate can prevent the deleterious in vitro actions of AGEs on osteoblastic cells in culture by mechanisms that involve calcium channel, MAPK and b-catenin activation.
In VitroEffects of Strontium on Proliferation and Osteoinduction of Human Preadipocytes
Stem Cells International, 2015
Development of tools to be used for in vivo bone tissue regeneration focuses on cellular models and differentiation processes. In searching for all the optimal sources, adipose tissue-derived mesenchymal stem cells (hADSCs or preadipocytes) are able to differentiate into osteoblasts with analogous characteristics to bone marrow mesenchymal stem cells, producing alkaline phosphatase (ALP), collagen, osteocalcin, and calcified nodules, mainly composed of hydroxyapatite (HA). The possibility to influence bone differentiation of stem cells encompasses local and systemic methods, including the use of drugs administered systemically. Among the latter, strontium ranelate (SR) represents an interesting compound, acting as an uncoupling factor that stimulates bone formation and inhibits bone resorption. The aim of our study was to evaluate the in vitro effects of a wide range of strontium (Sr 2+) concentrations on proliferation, ALP activity, and mineralization of a novel finite clonal hADSCs cell line, named PA20-h5. Sr 2+ promoted PA20-h5 cell proliferation while inducing the increase of ALP activity and gene expression as well as HA production during in vitro osteoinduction. These findings indicate a role for Sr 2+ in supporting bone regeneration during the process of skeletal repair in general, and, more specifically, when cell therapies are applied.
Bone, 2011
Background: The mechanism for the uncoupling effects of Sr on bone remains to be evaluated. Osteoblasts play important roles in osteoclastogenesis through regulating receptor activated nuclear factor kappa B (RANK) ligand (RANKL) and osteoprotegerin (OPG) expression. We hypothesize that OPG plays an important role in the cross-talk between osteoclasts and osteoblasts in response to Sr treatment. Materials and methods: MC3T3E1 cells were treated with Sr chloride (0-3 mM) and conditioned media were collected at 24 h after the treatment. The effect of conditioned media on osteoclastogenesis was evaluated by tartrate-resistant acid phosphatase (TRAP) staining and bone resorption pits analysis. OPG and RANKL mRNA expressions in osteoblastic cells and protein secretion in the conditioned media were analyzed with real-time PCR and ELISA assay, respectively. The role of OPG in Sr-mediated inhibition of osteoclastogenesis was further evaluated with anti-OPG antibody in pre-osteoclastic cells. The role of OPG in Sr-mediated uncoupling effects on osteoporotic bone was evaluated by an animal study. Ovariectomized rats were oral administrated with vehicle or Sr chloride for two months supplemented with anti-IgG antibody (control) or anti-OPG antibody. The effects of OPG neutralization after Sr treatment on bone metabolism were analyzed by microCT, bone histomorphometry and biochemical analysis. Results: The conditioned media derived from Sr-treated osteoblastic cells exerted a dose-dependent inhibitory effect on osteoclastic differentiation and resorptive activity in pre-osteoclastic cells. OPG mRNA expression and protein secretion in osteoblastic cells were significantly increased after Sr treatment. Neutralization with anti-OPG antibody abolished the inhibitory effect of conditioned media on RANKL-induced osteoclastogenesis. The uncoupling effects of Sr treatment on trabecular bone were evidenced by greater bone volume and trabecular number, greater osteoid surface and bone formation rate, while less osteoclast surface. These effects were attenuated by the OPG neutralization by anti-OPG antibody injection. Conclusion: The evidences from the in vitro and in vivo studies suggested that OPG played an important role in the uncoupling effect of Sr on bone metabolism, possibly by acting as a cross-talk molecule between osteoclasts and osteoblasts in response to Sr treatment.
Cell and Tissue Research, 2013
We describe effects of strontium ranelate treatment on intact mineralized nodules produced in osteoblast cell cultures. We analyzed the matrix directly at the cell culture surfaces following treatment with 0.05 and 0.5 mM Sr 2+. This method allowed for data to be obtained from intact nodules, rather than from extracted samples. The bone-like nature of the matrix was evaluated by using attenuated total reflection Fourier transform infrared spectroscopy and the incorporation of Sr into the nodules was investigated by using both energy dispersive Xray spectroscopy and synchrotron radiation micro X-ray fluorescence. We observed typical mineralized nodules in all of the cell cultures. However, the formation of these nodules was markedly increased in cultures treated with 0.5 mM Sr 2+. In all of the cultures, the nature of the intact matrix was similar to that described in native bone tissue, being comprised of a poorly crystalline CO 3 2−-containing apatite and a collagenous matrix. This indicated that treatment had no deleterious effects on the matrix. Moreover, the nodules presented Ca and P as the main chemical components, confirming their bone-like mineralized nature. The incorporation of Sr into the nodules was clearly observed in the treated cultures, with their relative Sr content [Sr/(Ca+Sr) ratio] being markedly increased in a dosedependent manner. Thus, strontium ranelate promoted an increase in the formation of mineralized nodules in osteoblast cell cultures while preserving the bone-like nature of the matrix at the tissue level. We further demonstrated that Sr was incorporated into the intact nodules formed during treatment. Keywords Strontium ranelate. Mineralized nodules. Osteoblast cell. In vitro mineralization. Bone. Biomineralization This study was supported by CNPq and FAPERJ (Brazil) and by the CAPES/COFECUB program no. 628/09 (Brazil/France cooperation).
Effect of strontium ranelate on bone remodeling
Acta odontológica latinoamericana : AOL, 2012
Osteoporosis is a disease in which the microarchitecture of bone tissue deteriorates, with consequent loss of bone mass. Strontium ranelate (SrR) is currently used for treatment of the condition. SrR may have a dual effect: anabolic (stimulating pre-osteoblast replication) and anti-catabolic (reducing osteoclastic activity). However, its mechanism of action has not yet been completely elucidated. The aim of this study is to evaluate the effect of SrR on bone remodeling in healthy Wistar rats. Two-month old female Wistar rats were administered SrR (2 g/L) in drinking water for 30 weeks. Oriented histological sections were prepared from lower jaw and tibia and stained with H&E, and the following histomorphometric parameters were evaluated: a) in interradicular bone: bone volume, and percentages of bone-formation, quiescent and bone-resorption surfaces; and b) in tibia: bone volume, total thickness of growth cartilage, thickness of hypertrophic cartilage zone and number of megakaryocyt...
BioMed research international, 2014
Age-related bone loss and osteoporosis are associated with bone remodeling changes that are featured with decreased trabecular and periosteal bone formation relative to bone resorption. Current anticatabolic therapies focusing on the inhibition of bone resorption may not be sufficient in the prevention or reversal of age-related bone deterioration and there is a big need in promoting osteoblastogenesis and bone formation. Enhanced understanding of the network formed by key signaling pathways and molecules regulating bone forming cells in health and diseases has therefore become highly significant. The successful development of agonist/antagonist of the PTH and Wnt signaling pathways are profits of the understanding of these key pathways. As the core component of an approved antiosteoporosis agent, strontium takes its effect on osteoblasts at multilevel through multiple pathways, representing a good example in revealing and exploring anabolic mechanisms. The recognition of strontium ...
Biometals : an international journal on the role of metal ions in biology, biochemistry, and medicine, 2014
Strontium ranelate (SR) is an orally administered and bone-targeting anti-osteoporotic agent that increases osteoblast-mediated bone formation while decreasing osteoclastic bone resorption, and thus reduces the risk of vertebral and femoral bone fractures in postmenopausal women with osteoporosis. Osteoblastic alkaline phosphatase (ALP) is a key enzyme involved in the process of bone formation and osteoid mineralization. In this study we investigated the direct effect of strontium (SR and SrCl 2 ) on the activity of ALP obtained from UMR106 osteosarcoma cells, as well as its possible interactions with the divalent cations Zn 2? and Mg 2? . In the presence of Mg 2? , both SR and SrCl 2 (0.05-0.5 mM) significantly increased ALP activity (15-66 % above basal), and this was dose-dependent in the case of SR. The stimulatory effect of strontium disappeared in the absence of Mg 2? . The cofactor Zn 2? also increased ALP activity (an effect that reached a plateau at 2 mM), and co-incubation of 2 mM Zn 2? with 0.05-0.5 mM SR showed an additive effect on ALP activity stimulation. SR induced a dose-dependent decrease in the Km of ALP (and thus an increase in affinity for its substrate) with a maximal effect at 0.1 mM. Co-incubation with 2 mM Zn 2? further decreased Km in all cases. These direct effects of SR on osteoblastic ALP activity could be indicating an alternative mechanism by which this compound may regulate bone matrix mineralization.