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Abstract
Prostaglandins (PGs) are highly bioactive fatty acids. PGs, especially prostaglandin E2 (PGE2), are abundantly produced by cells of both the bone-forming (osteoblast) lineage and the bone-resorbing (osteoclast) lineage. The inducible cyclooxygenase, COX-2, is largely responsible for most PGE2 production in bone, and once released, PGE2 is rapidly degraded in vivo. COX-2 is induced by multiple agonists - hormones, growth factors, and proinflammatory factors - and the resulting PGE2 may mediate, amplify, or, as we have recently shown for parathyroid hormone (PTH), inhibit responses to these agonists. In vitro, PGE2 can directly stimulate osteoblast differentiation and, indirectly via stimulation of RANKL in osteoblastic cells, stimulate the differentiation of osteoclasts. The net balance of these two effects of PGE2 in vivo on bone formation and bone resorption has been hard to predict and, as expected for such a widespread local factor, hard to study. Some of the complexity of PGE2 actions on bone can be explained by the fact that there are four receptors for PGE2 (EP1-4). Some of the major actions of PGE2 in vitro occur via EP2 and EP4, both of which can stimulate cAMP signaling, but there are other distinct signaling pathways, important in other tissues, which have not yet been fully elucidated in bone cells. Giving PGE2 or agonists of EP2 and EP4 to accelerate bone repair has been examined with positive results. Further studies to clarify the pathways of PGE2 action in bone may allow us to identify new and more effective ways to deliver the therapeutic benefits of PGE2 in skeletal disorders.
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Affiliation(s)
- Carol Pilbeam
- Department of Medicine and Musculoskeletal Institute, UConn Health, Farmington, CT, USA.
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2
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Yu L, Ma X, Sun J, Tong J, Shi L, Sun L, Zhang J. Fluid shear stress induces osteoblast differentiation and arrests the cell cycle at the G0 phase via the ERK1/2 pathway. Mol Med Rep 2017; 16:8699-8708. [PMID: 28990082 PMCID: PMC5779962 DOI: 10.3892/mmr.2017.7720] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2017] [Accepted: 08/10/2017] [Indexed: 11/05/2022] Open
Abstract
Numerous studies have demonstrated that fluid shear stress (FSS) may promote the proliferation and differentiation of osteoblast cells. However, proliferation and differentiation are mutually exclusive processes and are unlikely to be promoted by FSS simultaneously. Cell proliferation and differentiation induced by FSS has rarely been reported. In order to provide an insight into this process, the present study investigated the effects of FSS on osteoblast‑like MC3T3 cells in the G0/G1 phase, the period during which the fate of a cell is determined. The results of the present study demonstrated that FSS promoted alkaline phosphatase (ALP) activity, and the mRNA expression and protein expression of osteocalcin, collagen type I and runt‑related transcription factor 2 (Runx2), while inhibiting DNA synthesis and arresting the cell cycle at the G0/G1 phase. The increase in Runx2 and ALP activity was accompanied by the activation of calcium/calmodulin‑dependent protein kinase type II (CaMK II) and extracellular signal‑regulated kinases 1/2 (ERK1/2), which was completely abolished by treatment with KN93 and U0126, respectively. In addition, the inhibition of ERK1/2, although not CaMK II, decreased p21Cip/Kip activity, resulting in an increase in cell number and S phase re‑entry. The results of the present study indicated that in the G0/G1 phase, FSS promoted osteoblast differentiation via the CaMK II and ERK1/2 signaling pathways, and blocked the cell cycle at the G0/G1 phase via the ERK1/2 pathway only. The present findings provided an increased understanding of osteoblastic mechanobiology.
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Affiliation(s)
- Liyin Yu
- Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, P.R. China
| | - Xingfeng Ma
- Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, P.R. China
| | - Junqin Sun
- Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, P.R. China
| | - Jie Tong
- Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, P.R. China
| | - Liang Shi
- Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, P.R. China
| | - Lijun Sun
- Institute of Sports Biology, Shaanxi Normal University, Xi'an, Shaanxi 710119, P.R. China
| | - Jianbao Zhang
- Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, P.R. China
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Kwack SJ, Lee BM. Comparative Cytotoxicity and Sperm Motility Using a Computer-Aided Sperm Analysis System (CASA) for Isomers of Phthalic Acid, a Common Final Metabolite of Phthalates. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2015; 78:1038-1050. [PMID: 26252616 DOI: 10.1080/15287394.2015.1067503] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The general population is exposed to phthalates through consumer products, diet, and medical devices. Phthalic acid (PA) is a common final metabolite of phthalates, and its isomers include isophthalic acid (IPA), terephthalic acid (TPA), and phthalaldehyde (o-phthalic acid, OPA). The purpose of this study was to investigate whether PA and PA isomers exert reproductive toxicity, including altered sperm movement. In vitro cell viability assays were comparatively performed using Sertoli and liver cell lines. In animal experiments, PA or PA isomers (10, 100, or 1000 mg/kg) were administered orally to Sprague-Dawley (SD) rats, and semen samples were analyzed by computer-aided sperm analysis (CASA). PA treatment produced a significant effect on curvilinear velocity (VCL), straight-line velocity (VSL), mean velocity or average path velocity (VAP), amplitude of lateral head displacement (ALH), and frequency of head displacement or beat cross-frequency (BCF), whereas IPA, TPA, and OPA induced no marked effects. In vitro cell viability assays showed that mouse normal testis cells (TM4) and human testis cancer cells (NTERA 2 cl. D1) were more sensitive to PA and OPA than mouse liver normal cells (NCTC clone 1469) and human fetal liver cells (FL 62891). Our study suggests that PA and PA isomers specifically produced significant in vitro and in vivo reproductive toxicity, particularly sperm toxicity and testis cell cytotoxicity. Of the isomers examined, PA appeared to be the most toxic and may serve as a surrogate biomarker for reproductive toxicity following mixed exposure to phthalates.
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Affiliation(s)
- Seung Jun Kwack
- a Department of Biochemistry and Health Science , College of Natural Sciences, Changwon National University , Changwon , Gyeongnam , South Korea
| | - Byung-Mu Lee
- b Division of Toxicology , College of Pharmacy, Sungkyunkwan University , Suwon , Gyeonggi-Do , Korea
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4
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During A, Penel G, Hardouin P. Understanding the local actions of lipids in bone physiology. Prog Lipid Res 2015; 59:126-46. [PMID: 26118851 DOI: 10.1016/j.plipres.2015.06.002] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 06/12/2015] [Accepted: 06/18/2015] [Indexed: 12/19/2022]
Abstract
The adult skeleton is a metabolically active organ system that undergoes continuous remodeling to remove old and/or stressed bone (resorption) and replace it with new bone (formation) in order to maintain a constant bone mass and preserve bone strength from micro-damage accumulation. In that remodeling process, cellular balances--adipocytogenesis/osteoblastogenesis and osteoblastogenesis/osteoclastogenesis--are critical and tightly controlled by many factors, including lipids as discussed in the present review. Interest in the bone lipid area has increased as a result of in vivo evidences indicating a reciprocal relationship between bone mass and marrow adiposity. Lipids in bones are usually assumed to be present only in the bone marrow. However, the mineralized bone tissue itself also contains small amounts of lipids which might play an important role in bone physiology. Fatty acids, cholesterol, phospholipids and several endogenous metabolites (i.e., prostaglandins, oxysterols) have been purported to act on bone cell survival and functions, the bone mineralization process, and critical signaling pathways. Thus, they can be regarded as regulatory molecules important in bone health. Recently, several specific lipids derived from membrane phospholipids (i.e., sphingosine-1-phosphate, lysophosphatidic acid and different fatty acid amides) have emerged as important mediators in bone physiology and the number of such molecules will probably increase in the near future. The present paper reviews the current knowledge about: (1°) bone lipid composition in both bone marrow and mineralized tissue compartments, and (2°) local actions of lipids on bone physiology in relation to their metabolism. Understanding the roles of lipids in bone is essential to knowing how an imbalance in their signaling pathways might contribute to bone pathologies, such as osteoporosis.
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Affiliation(s)
- Alexandrine During
- Université Lille 2, Laboratoire de Physiopathologie des maladies osseuses inflammatoires (PMOI), EA4490, Faculté de Chirurgie dentaire, Lille, France.
| | - Guillaume Penel
- Université Lille 2, Laboratoire de Physiopathologie des maladies osseuses inflammatoires (PMOI), EA4490, Faculté de Chirurgie dentaire, Lille, France
| | - Pierre Hardouin
- Université Lille 2, Laboratoire de Physiopathologie des maladies osseuses inflammatoires (PMOI), EA4490, Faculté de Chirurgie dentaire, Lille, France; Université ULCO, Laboratoire de Physiopathologie des maladies osseuses inflammatoires (PMOI), EA4490, Boulogne-sur-Mer, France
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Oh N, Kim S, Hosoya K, Okumura M. Compensatory cellular reactions to nonsteroidal anti-inflammatory drugs on osteogenic differentiation in canine bone marrow-derived mesenchymal stem cells. J Vet Med Sci 2014; 76:629-36. [PMID: 24419976 PMCID: PMC4073330 DOI: 10.1292/jvms.13-0482] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The suppressive effects of nonsteroidal anti-inflammatory drugs (NSAIDs) on the
bone healing process have remained controversial, since no clinical data have clearly
shown the relationship between NSAIDs and bone healing. The aim of this study was to
assess the compensatory response of canine bone marrow-derived mesenchymal stem cells
(BMSCs) to several classes of NSAIDs, including carprofen, meloxicam, indomethacin and
robenacoxib, on osteogenic differentiation. Each of the NSAIDs (10 µM)
was administered during 20 days of the osteogenic process with human recombinant IL-1β (1
ng/ml) as an inflammatory stimulator. Gene expression
of osteoblast differentiation markers (alkaline phosphatase and osteocalcin), receptors of
PGE2 (EP2 and EP4) and enzymes for prostaglandin (PG) E2 synthesis (COX-1,
COX-2, cPGES and mPGES-1) was measured by using quantitative reverse
transcription-polymerase chain reaction. Protein production levels of alkaline
phosphatase, osteocalcin and PGE2 were quantified using an alkaline phosphatase
activity assay, osteocalcin immunoassay and PGE2 immunoassay, respectively.
Histologic analysis was performed using alkaline phosphatase staining, von Kossa staining
and alizarin red staining. Alkaline phosphatase and calcium deposition were suppressed by
all NSAIDs. However, osteocalcin production showed no significant suppression by NSAIDs.
Gene expression levels of PGE2-related receptors and enzymes were upregulated
during continuous treatment with NSAIDs, while certain channels for PGE2
synthesis were utilized differently depending on the kind of NSAIDs. These data suggest
that canine BMSCs have a compensatory mechanism to restore PGE2 synthesis,
which would be an intrinsic regulator to maintain differentiation of osteoblasts under
NSAID treatment.
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Affiliation(s)
- Namgil Oh
- Laboratory of Veterinary Surgery, Department of Veterinary Clinical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan
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Bang DY, Lee IK, Lee BM. Toxicological characterization of phthalic Acid. Toxicol Res 2013; 27:191-203. [PMID: 24278572 PMCID: PMC3834394 DOI: 10.5487/tr.2011.27.4.191] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2011] [Revised: 10/15/2011] [Accepted: 10/25/2011] [Indexed: 11/20/2022] Open
Abstract
There has been growing concern about the toxicity of phthalate esters. Phthalate esters are being used widely for the production of perfume, nail varnish, hairsprays and other personal/cosmetic uses. Recently, exposure to phthalates has been assessed by analyzing urine for their metabolites. The parent phthalate is rapidly metabolized to its monoester (the active metabolite) and also glucuronidated, then excreted. The objective of this study is to evaluate the toxicity of phthalic acid (PA), which is the final common metabolic form of phthalic acid esters (PAEs). The individual PA isomers are extensively employed in the synthesis of synthetic agents, for example isophthalic acid (IPA), and terephthalic acid (TPA), which have very broad applications in the preparation of phthalate ester plasticizers and components of polyester fiber, film and fabricated items. There is a broad potential for exposure by industrial workers during the manufacturing process and by the general public (via vehicle exhausts, consumer products, etc). This review suggests that PA shows in vitro and in vivo toxicity (mutagenicity, developmental toxicity, reproductive toxicity, etc.). In addition, PA seems to be a useful biomarker for multiple exposure to PAEs in humans.
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Affiliation(s)
- Du Yeon Bang
- Laboratory of Toxicology, College of Pharmacy, Sungkyunkwan University, Suwon 440-746, Korea
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Choudhary S, Blackwell K, Voznesensky O, Roy AD, Pilbeam C. Prostaglandin E2 acts via bone marrow macrophages to block PTH-stimulated osteoblast differentiation in vitro. Bone 2013; 56:31-41. [PMID: 23639875 PMCID: PMC4073290 DOI: 10.1016/j.bone.2013.04.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 04/19/2013] [Accepted: 04/20/2013] [Indexed: 12/26/2022]
Abstract
Intermittent PTH is the major anabolic therapy for osteoporosis while continuous PTH causes bone loss. PTH acts on the osteoblast (OB) lineage to regulate bone resorption and formation. PTH also induces cyclooxygenase-2 (COX-2), producing prostaglandin E2 (PGE(2)) that can act on both OBs and osteoclasts (OCs). Because intermittent PTH is more anabolic in Cox-2 knockout (KO) than wild type (WT) mice, we hypothesized COX-2 might contribute to the effects of continuous PTH by suppressing PTH-stimulated differentiation of mesenchymal stem cells into OBs. We compared effects of continuous PTH on bone marrow stromal cells (BMSCs) and primary OBs (POBs) from Cox-2 KO mice, mice with deletion of PGE(2) receptors (Ptger(4) and Ptger(2) KO mice), and WT controls. PTH increased OB differentiation in BMSCs only in the absence of COX-2 expression or activity. In the absence of COX-2, PTH stimulated differentiation if added during the first week of culture. In Cox-2 KO BMSCs, PTH-stimulated differentiation was prevented by adding PGE(2) to cultures. Co-culture of POBs with M-CSF-expanded bone marrow macrophages (BMMs) showed that the inhibition of PTH-stimulated OB differentiation required not only COX-2 or PGE(2) but also BMMs. Sufficient PGE(2) to mediate the inhibitory effect was made by either WT POBs or WT BMMs. The inhibitory effect mediated by COX-2/PGE(2) was transferred by conditioned media from RANKL-treated BMMs and could be blocked by osteoprotegerin, which interferes with RANKL binding to its receptor on OC lineage cells. Deletion of Ptger(4), but not Ptger(2), in BMMs prevented the inhibition of PTH-stimulated OB differentiation. As expected, PGE(2) also stimulated OB differentiation, but when given in combination with PTH, the stimulatory effects of both were abrogated. These data suggest that PGE(2), acting via EP4R on BMMs committed to the OC lineage, stimulated secretion of a factor or factors that acted to suppress PTH-stimulated OB differentiation. This suppression of OB differentiation could contribute to the bone loss seen with continuous PTH in vivo.
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MESH Headings
- Adipogenesis/drug effects
- Adipogenesis/genetics
- Animals
- Bone Marrow Cells/cytology
- Bone Marrow Cells/drug effects
- Bone Marrow Cells/metabolism
- Cattle
- Cell Differentiation/drug effects
- Cell Differentiation/genetics
- Cells, Cultured
- Culture Media, Conditioned/pharmacology
- Cyclooxygenase 2/metabolism
- Dinoprostone/pharmacology
- Gene Expression Regulation/drug effects
- Hematopoietic System/cytology
- Macrophages/cytology
- Macrophages/drug effects
- Macrophages/metabolism
- Mice
- Mice, Knockout
- Osteoblasts/cytology
- Osteoblasts/drug effects
- Osteoblasts/enzymology
- Osteocalcin/genetics
- Osteocalcin/metabolism
- Parathyroid Hormone/pharmacology
- RANK Ligand/pharmacology
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Prostaglandin E, EP2 Subtype/deficiency
- Receptors, Prostaglandin E, EP2 Subtype/metabolism
- Receptors, Prostaglandin E, EP4 Subtype/deficiency
- Receptors, Prostaglandin E, EP4 Subtype/metabolism
- Stromal Cells/cytology
- Stromal Cells/drug effects
- Stromal Cells/enzymology
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Affiliation(s)
| | | | | | | | - Carol Pilbeam
- Corresponding author at: University of Connecticut Health Center, 263 Farmington Avenue, MC5456, Farmington, CT 06030, USA. Fax: +1 860 679 1932. (C. Pilbeam)
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9
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Kitz K, Windischhofer W, Leis HJ, Huber E, Kollroser M, Malle E. 15-Deoxy-Δ12,14-prostaglandin J2 induces Cox-2 expression in human osteosarcoma cells through MAPK and EGFR activation involving reactive oxygen species. Free Radic Biol Med 2011; 50:854-65. [PMID: 21236332 DOI: 10.1016/j.freeradbiomed.2010.12.039] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Revised: 12/14/2010] [Accepted: 12/31/2010] [Indexed: 11/25/2022]
Abstract
Prostaglandins (PGs), important modulators in bone biology, may also contribute to tumor formation and progression in human osteosarcoma. 15-Deoxy-Δ(12,14)-PGJ(2) (15d-PGJ(2)), a metabolite of PGD(2) and PPARγ-ligand, exerts a panel of biological activities via receptor-dependent and -independent mechanisms. As inducible cyclooxygenase-2 (Cox-2) is a candidate inflammatory marker in human osteosarcoma and a rate-limiting enzyme in PG biosynthesis, this study aimed at investigating intracellular redox status and signaling cascades leading to Cox-2 induction in human MG-63 osteosarcoma cells. 15d-PGJ(2) induced the accumulation of reactive oxygen species (ROS) that in turn may lead to upregulation of Cox-2 via two different routes in a PPARγ-independent manner. First, phosphorylation of p38 MAPK directly enhances Cox-2 expression by promoting mRNA stability. Second, 15d-PGJ(2) induces activation of epidermal growth factor receptors and downstream activation of Cox-2 via phosphorylation of p42/44 MAPK. Glutathione precursor molecules reversed enhanced ROS levels and Cox-2 expression. Functional activity of Cox-2 expression was tested by measurement of PGE(2) and PGF(2α). The synthetic compound 9,10-dihydro-15d-PGJ(2) lacking the α,β-unsaturated carbonyl group in the cyclopentenone ring did not exhibit the cellular responses observed with 15d-PGJ(2). We conclude that the electrophilic carbon atom of 15d-PGJ(2) is responsible for alterations in intracellular redox status and Cox-2 expression.
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Affiliation(s)
- Kerstin Kitz
- Department of Pediatrics and Adolescence Medicine, Research Unit of Osteological Research and Analytical Mass Spectrometry, Medical University of Graz, A-8036 Graz, Austria
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10
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Weinberg E, Zeldich E, Weinreb MM, Moses O, Nemcovsky C, Weinreb M. Prostaglandin E2 inhibits the proliferation of human gingival fibroblasts via the EP2 receptor and Epac. J Cell Biochem 2010; 108:207-15. [PMID: 19582788 DOI: 10.1002/jcb.22242] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Elevated levels of prostaglandins such as PGE(2) in inflamed gingiva play a significant role in the tissue destruction caused by periodontitis, partly by targeting local fibroblasts. Only very few studies have shown that PGE(2) inhibits the proliferation of a gingival fibroblast (GF) cell line, and we expanded this research by using primary human GFs (hGFs) and looking into the mechanisms of the PGE(2) effect. GFs derived from healthy human gingiva were treated with PGE(2) and proliferation was assessed by measuring cell number and DNA synthesis and potential signaling pathways were investigated using selective activators or inhibitors. PGE(2) inhibited the proliferation of hGFs dose-dependently. The effect was mimicked by forskolin (adenylate cyclase stimulator) and augmented by IBMX (a cAMP-breakdown inhibitor), pointing to involvement of cAMP. Indeed, PGE(2) and forskolin induced cAMP generation in these cells. Using selective EP receptor agonists we found that the anti-proliferative effect of PGE(2) is mediated via the EP(2) receptor (which is coupled to adenylate cyclase activation). We also found that the effect of PGE(2) involved activation of Epac (exchange protein directly activated by cAMP), an intracellular cAMP sensor, and not PKA. While serum increased the amount of phospho-ERK in hGFs by approximately 300%, PGE(2) decreased it by approximately 50%. Finally, the PGE(2) effect does not require endogenous production of prostaglandins since it was not abrogated by two COX-inhibitors. In conclusion, in human gingival fibroblasts PGE(2) activates the EP(2)-cAMP-Epac pathway, reducing ERK phosphorylation and inhibiting proliferation. This effect could hamper periodontal healing and provide further insights into the pathogenesis of inflammatory periodontal disease.
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Affiliation(s)
- Evgeny Weinberg
- Department of Oral Biology, The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel-Aviv University, Tel-Aviv, Israel
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11
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Pagel CN, Song SJ, Loh LH, Tudor EM, Murray-Rust TA, Pike RN, Mackie EJ. Thrombin-stimulated growth factor and cytokine expression in osteoblasts is mediated by protease-activated receptor-1 and prostanoids. Bone 2009; 44:813-21. [PMID: 19442625 DOI: 10.1016/j.bone.2008.12.031] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Revised: 12/22/2008] [Accepted: 12/31/2008] [Indexed: 11/26/2022]
Abstract
Thrombin exerts multiple effects upon osteoblasts including stimulating proliferation, and inhibiting osteoblast differentiation and apoptosis. Some of these effects are believed to be mediated by the synthesis and secretion of autocrine factors such as growth factors and cytokines. Many but not all cellular responses to thrombin are mediated by members of the protease-activated receptor (PAR) family of G protein-coupled receptors. The current study was undertaken to investigate the nature of thrombin's induction of autocrine factors by analysing the expression of twelve candidate genes in thrombin-stimulated primary mouse osteoblasts. Analysis by quantitative reverse transcription polymerase chain reaction (qRT-PCR) demonstrated that thrombin induced transforming growth factor beta, cyclooxygenase-2, tenascin C, fibroblast growth factor-1 and -2, connective tissue growth factor and interleukin-6 expression in wild type osteoblasts, but not PAR-1 null mouse osteoblasts. Induction of all the thrombin-responsive genes was blocked by the presence of the non-selective cyclooxygenase inhibitor indomethacin. Further studies were conducted on interleukin-6, which was the gene that showed the greatest increase in expression following stimulation of osteoblast-like cells with thrombin. A PAR-1-specific activating peptide, but neither a PAR-4-activating peptide nor catalytically inactive thrombin induced release of interleukin-6 by osteoblasts. Furthermore, in the presence of the selective cyclooxygenase-1 and -2 inhibitors SC-560 and NS-398 thrombin-induced interleukin-6 release was prevented. Levels of both prostaglandin E(2) and interleukin-6 in medium conditioned by thrombin-stimulated osteoblast-like cells were found to be significantly increased compared to medium conditioned by non-stimulated cells, however release of prostaglandin E(2) was found to precede release of interleukin-6. Treatment of isolated osteoblast-like cells with a number of synthetic prostanoids stimulated secretion of interleukin-6 with differing potencies. These studies suggest that activation of PAR-1 on osteoblasts by thrombin induces cyclooxygenase activity, which in turn results in the increased expression of multiple secreted factors. The induction of these secreted factors may act in an autocrine fashion to alter osteoblast function, allowing these cells to participate in the earliest stages of bone healing by both autocrine and paracrine mechanisms.
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Affiliation(s)
- Charles N Pagel
- School of Veterinary Science, University of Melbourne, Parkville, Victoria, Australia
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12
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Naruse K, Mikuni-Takagaki Y, Urabe K, Uchida K, Itoman M. Therapeutic ultrasound induces periosteal ossification without apparent changes in cartilage. Connect Tissue Res 2009; 50:55-63. [PMID: 19212853 DOI: 10.1080/03008200802419855] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Low intensity pulsed ultrasound (LIPUS) is an extremely useful noninvasive treatment which halves the duration of fracture healing when the bone is exposed once a day for 20 min. To elucidate the direct reactions of bone and cartilage, dissected rat femora were immobilized in culture dish wells, exposed to LIPUS from a certain angle every day, and the local pattern of ossification was analyzed in relation to the ultrasound. Daily 20-min exposures were started 24 hr after isolation of the femora, and at days 5, 10, and 15, samples were harvested for measurements, morphological, and histochemical analyses. While the gross features of the samples were identical to the untreated controls, extended mineralization of the periosteum was observed with alizarin red staining, antiosteocalcin immunohistochemical staining, and micro-three dimensional computed tomography. Interestingly, the newly deposited mineral was found perpendicular to the ultrasound path, strongly suggesting that LIPUS accelerates periosteal bone formation. Zones of epiphyseal cartilage and hypertrophic and calcified cartilage did not exhibit any differences with and without this exposure. LIPUS also did not influence the secreted proteoglycan components or amounts in the culture medium. The absence of any additional longitudinal growth of the femur demonstrated that LIPUS did not accelerate endochondral bone formation. We conclude that cartilage alone does not directly respond to therapeutic ultrasound, whereas the periosteum does.
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Affiliation(s)
- Kouji Naruse
- Department of Orthopedic Surgery, Kitasato University School of Medicine, Sagamihara, Japan.
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13
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Hikiji H, Takato T, Shimizu T, Ishii S. The roles of prostanoids, leukotrienes, and platelet-activating factor in bone metabolism and disease. Prog Lipid Res 2008; 47:107-26. [DOI: 10.1016/j.plipres.2007.12.003] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2007] [Revised: 11/29/2007] [Accepted: 12/04/2007] [Indexed: 12/11/2022]
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14
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Chang JK, Li CJ, Wu SC, Yeh CH, Chen CH, Fu YC, Wang GJ, Ho ML. Effects of anti-inflammatory drugs on proliferation, cytotoxicity and osteogenesis in bone marrow mesenchymal stem cells. Biochem Pharmacol 2007; 74:1371-82. [PMID: 17714695 DOI: 10.1016/j.bcp.2007.06.047] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2007] [Revised: 06/29/2007] [Accepted: 06/29/2007] [Indexed: 11/22/2022]
Abstract
Nonsteroidal anti-inflammatory drugs (NSAIDs) were found to suppress proliferation and induce cell death in cultured osteoblasts, and steroids were found to decrease the osteogenesis potential of mesenchymal stem cells. In this study, we further tested the effects of anti-inflammatory drugs (AIDs) on the functions of bone marrow mesenchymal stem cells (BMSCs). The BMSCs from mice (D1-cells) and humans (hBMSCs) were treated with dexamethasone (10(-7) to 10(-6) M), cyclooxygenase-2 (COX-2) selective NSAIDs (10(-6) to 10(-5) M) and non-selective NSAIDs (10(-5) to 10(-4) M). Drug effects on proliferation, cell cycle kinetics, cytotoxicity and mRNA and protein expressions of cell cycle regulators were tested. The osteogenesis potential of D1-cells were evaluated by testing mRNA expressions of type Ialpha collagen and osteocalcin 2-8 days after treatments, and testing mineralization 1-3 weeks after treatments. The results showed that all the tested drugs suppressed proliferation and arrested cell cycle of D1-cells, but no significant cytotoxic effects was found. Prostaglandin E1, E2 and F2alpha couldn't rescue the effects of AIDs on proliferation. The p27kip1 expression was up-regulated by indomethacin, celecoxib and dexamethasone in both D1-cells and hBMSCs. Higher concentrations of indomethacin and dexamethasone also up-regulated p21Cip1/Waf1 expression in hBMSCs, and so did celecoxib on D1-cells. Expressions of cyclin E1 and E2 were down-regulated by these AIDs in D-cells, while only cyclin E2 was down-regulated by dexamethasone in hBMSCs. All the tested NSAIDs revealed no obvious detrimental effects on osteogenic differentiation of D1-cells. These results suggest that the proliferation suppression of AIDs on BMSCs may act via affecting expressions of cell cycle regulators, but not prostaglandin-related mechanisms.
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Affiliation(s)
- Je-Ken Chang
- Department of Orthopaedics, Faculty of Medicine, Kaohsiung Medical University, and Kaohsiung Medical University Hospital, Taiwan
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15
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Milcan A, Colak M, Eskandari G. Misoprostol enhances early fracture healing: a preliminary biochemical study on rats. Bone 2007; 41:611-3. [PMID: 17681893 DOI: 10.1016/j.bone.2007.07.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2007] [Revised: 06/14/2007] [Accepted: 07/04/2007] [Indexed: 11/25/2022]
Abstract
The purpose of this study was to demonstrate if misoprostol, a methyl derivative of prostaglandin E1, enhanced fracture healing in 54 male adult Sprague-Dawley rats. The base level of serum alkaline phosphatase (ALP) in 6 randomly selected rats was measured. Rats were then randomly separated into 3 groups and their tibias fractured. First and second groups received misoprostol for 4 weeks, 100 and 300 microg/kg/day respectively via oral route. The third group had no misoprostol. p<0.05 was considered significant. Elevation of ALP level in the 2nd week was significant in group 1, it was not in group 2 or 3; in the 4th week it was significant in all groups. In conclusion dosage dependent osteoinductive effect of misoprostol was shown in the early bone healing period. Biochemical findings in the latter period did not show any inhibitory effect of misoprostol on bone healing. Further studies, probably biomechanical, may be required for the final verdict.
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Affiliation(s)
- A Milcan
- University of Mersin, Faculty of Medicine, Department of Orthopaedics and Traumatology, Turkey.
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16
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Xu Z, Choudhary S, Okada Y, Voznesensky O, Alander C, Raisz L, Pilbeam C. Cyclooxygenase-2 gene disruption promotes proliferation of murine calvarial osteoblasts in vitro. Bone 2007; 41:68-76. [PMID: 17467356 PMCID: PMC1993538 DOI: 10.1016/j.bone.2007.03.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2006] [Revised: 02/21/2007] [Accepted: 03/12/2007] [Indexed: 12/31/2022]
Abstract
Cyclooxygenase-2 (COX-2) is highly expressed in osteoblasts, and COX-2 produced prostaglandins (PGs) can increase osteoblastic differentiation in vitro. The goal of this study was to examine effects of COX-2 expression on calvarial osteoblastic proliferation and apoptosis. Primary osteoblasts (POBs) were cultured from calvariae of COX-2 wild-type (WT) and knockout (KO) mice. POB proliferation was evaluated by (3)H-thymidine incorporation and analysis of cell replication and cell cycle distribution by flow cytometry. POB apoptosis was evaluated by annexin and PI staining on flow cytometry. As expected, PGE(2) production and alkaline phosphatase (ALP) activity were increased in WT cultures compared to KO cultures. In contrast, cell numbers were decreased in WT compared to KO cells by day 4 of culture. Proliferation, measured on days 3-7 of culture, was 2-fold greater in KO than in WT POBs and associated with decreased Go/G1 and increased S cell cycle distribution. There was no significant effect of COX-2 genotype on apoptosis under basal culture conditions on day 5 of culture. Cell growth was decreased in KO POBs by the addition of PGE(2) or a protein kinase A agonist and increased in WT POBs by the addition of NS398, a selective COX-2 inhibitor. In contrast, differentiation and cell growth in marrow stromal cell (MSC) cultures, evaluated by ALP and crystal violet staining respectively, were increased in MSCs from WT mice compared to MSCs from KO mice, and exogenous PGE(2) increased cell growth in KO MSC cultures. We conclude that PGs secondary to COX-2 expression decrease osteoblastic proliferation in cultured calvarial cells but increase growth of osteoblastic precursors in MSC cultures.
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Affiliation(s)
- Zheng Xu
- Department of Medicine, University of Connecticut Health Center, Farmington, CT 06030
| | - Shilpa Choudhary
- Department of Medicine, University of Connecticut Health Center, Farmington, CT 06030
| | - Yosuke Okada
- First department of Internal Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu 807-8555 Japan
| | - Olga Voznesensky
- Department of Medicine, University of Connecticut Health Center, Farmington, CT 06030
| | - Cynthia Alander
- Department of Medicine, University of Connecticut Health Center, Farmington, CT 06030
| | - Lawrence Raisz
- Department of Medicine, University of Connecticut Health Center, Farmington, CT 06030
| | - Carol Pilbeam
- Department of Medicine, University of Connecticut Health Center, Farmington, CT 06030
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17
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Hughes-Fulford M, Rodenacker K, Jütting U. Reduction of anabolic signals and alteration of osteoblast nuclear morphology in microgravity. J Cell Biochem 2006; 99:435-49. [PMID: 16619267 DOI: 10.1002/jcb.20883] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Bone loss has been repeatedly documented in astronauts after flight, yet little is known about the mechanism of bone loss in space flight. Osteoblasts were activated during space flight in microgravity (microg) with and without a 1 gravity (1 g) field and 24 genes were analyzed for early induction. Induction of proliferating cell nuclear antigen (PCNA), transforming growth factor beta (TGFbeta), cyclo-oxygenase-2 (cox-2), cpla2, osteocalcin (OC), c-myc, fibroblast growth factor-2 (fgf-2), bcl2, bax, and fgf-2 message as well as FGF-2 protein were significantly depressed in microg when compared to ground (gr). Artificial onboard gravity normalized the induction of c-myc, cox-2, TGFbeta, bax, bcl2, and fgf-2 message as well as FGF-2 protein synthesis in spaceflight samples. In normal gravity, FGF-2 induces bcl2 expression; we found that bcl2 expression was significantly reduced in microgravity conditions. Since nuclear shape is known to elongate in the absence of mitogens like FGF-2, we used high-resolution image-based morphometry to characterize changes in osteoblast nuclear architecture under microgravity, 1 g flight, and ground conditions. Besides changes in cell shape (roundish/elliptic), other high-resolution analyses show clear influences of gravity on the inner nuclear structure. These changes occur in the texture, arrangement, and contrast of nuclear particles and mathematical modeling defines the single cell classification of the osteoblasts. Changes in nuclear structure were evident as early as 24 h after exposure to microgravity. This documented alteration in nuclear architecture may be a direct result of decreased expression of autocrine and cell cycle genes, suggesting an inhibition of anabolic response in microg. Life on this planet has evolved in a normal gravity field and these data suggest that gravity plays a significant role in regulation of osteoblast transcription.
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Affiliation(s)
- Millie Hughes-Fulford
- Northern California Institute for Research and Education, San Francisco, California, USA.
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18
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Gregory LS, Kelly WL, Reid RC, Fairlie DP, Forwood MR. Inhibitors of cyclo-oxygenase-2 and secretory phospholipase A2 preserve bone architecture following ovariectomy in adult rats. Bone 2006; 39:134-42. [PMID: 16473054 DOI: 10.1016/j.bone.2005.12.017] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2005] [Revised: 11/16/2005] [Accepted: 12/29/2005] [Indexed: 12/30/2022]
Abstract
Epidemiological evidence and in vitro data suggest that COX-2 is a key regulator of accelerated remodeling. Accelerated states of osteoblast and osteoclast activity are regulated by prostaglandins in vitro, but experimental evidence for specific roles of cyclooxygenase-2 (COX-2) and secretory phospholipase A2 (sPLA2) in activated states of remodeling in vivo is lacking. The aim of this study was to determine the effect of specific inhibitors of sPLA2-IIa and COX-2 on bone remodeling activated by estrogen deficiency in adult female rats. One hundred and twenty-four adult female Wistar rats were ovariectomized (OVX) or sham-operated. Rats commenced treatment 14 days after surgery with either vehicle, a COX-2 inhibitor (DFU at 0.02 mg/kg/day and 2.0 mg/kg/day) or a sPLA2-group-IIa inhibitor (KH064 at 0.4 mg/kg/day and 4.0 mg/kg/day). Treatment continued daily until rats were sacrificed at 70 days or 98 days post-OVX. The right tibiae were harvested, fixed and embedded in methylmethacrylate for structural histomorphometric bone analysis at the proximal tibial metaphysis. The specific COX-2 or sPLA2 inhibitors prevented ovariectomy-induced (OVX-induced) decreases in trabecular connectivity (P<0.05); suppressed the acceleration of bone resorption; and maintained bone turnover at SHAM levels following OVX in the rat. The sPLA2 inhibitor significantly suppressed increases in osteoclast surface induced by OVX (P<0.05), while the effect of COX-2 inhibition was less marked. These findings demonstrate that inhibitors of COX-2 and sPLA2-IIa can effectively suppress OVX-induced bone loss in the adult rat by conserving trabecular bone mass and architecture through reduced bone remodeling and decreased resorptive activity. Moreover, we report an important role of sPLA2-IIa in osteoclastogenesis that may be independent of the COX-2 metabolic pathway in the OVX rat in vivo.
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Affiliation(s)
- Laura S Gregory
- Department of Anatomy and Developmental Biology, School of Biomedical Sciences, The University of Queensland, Brisbane Qld 4072, Australia.
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19
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Mehrotra M, Saegusa M, Voznesensky O, Pilbeam C. Role of Cbfa1/Runx2 in the fluid shear stress induction of COX-2 in osteoblasts. Biochem Biophys Res Commun 2006; 341:1225-30. [PMID: 16476583 DOI: 10.1016/j.bbrc.2006.01.084] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2006] [Accepted: 01/20/2006] [Indexed: 10/25/2022]
Abstract
Induction of cyclooxygenase-2 (COX-2) is thought to be important for the anabolic effects of mechanical loading. The transcription factor Cbfa1/Runx2 is essential for osteoblastic differentiation. We examined the role of Cbfa1 in the fluid shear stress (FSS) induction of COX-2 in MC3T3-E1 cells stably transfected with a COX-2 promoter-luciferase reporter. Cells were subjected to FSS for 30 min and returned to static culture (post-FSS). COX-2 mRNA and promoter activity peaked 0.5-1h and 2-3h, respectively, post-FSS. Mutation of the Cbfa1 consensus sequence at -267/-261 bp decreased the FSS fold-induction of luciferase activity by 50%. On electrophoretic mobility shift assay (EMSA), proteins binding to an oligonucleotide spanning the Cbfa1 site were supershifted by specific antibody to Cbfa1. FSS did not increase Cbfa1 binding on EMSA or Cbfa1 mRNA or protein levels. These data suggest that transcriptional activity of Cbfa1, independent of its level of expression, is necessary for maximal FSS induction of COX-2 in osteoblasts.
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Affiliation(s)
- Meenal Mehrotra
- Department of Medicine, University of Connecticut Health Center, Farmington, CT 06030, USA
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20
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Abstract
Rheumatoid arthritis, juvenile idiopathic arthritis, the seronegative spondyloarthropathies including psoriatic arthritis, and systemic lupus erythematosus are all examples of rheumatic diseases in which inflammation is associated with skeletal pathology. Although some of the mechanisms of skeletal remodeling are shared among these diseases, each disease has a unique impact on articular bone or on the axial or appendicular skeleton. Studies in human disease and in animal models of arthritis have identified the osteoclast as the predominant cell type mediating bone loss in arthritis. Many of the cytokines and growth factors implicated in the inflammatory processes in rheumatic diseases have also been demonstrated to impact osteoclast differentiation and function either directly, by acting on cells of the osteoclast-lineage, or indirectly, by acting on other cell types to modulate expression of the key osteoclastogenic factor receptor activator of nuclear factor (NF) kappaB ligand (RANKL) and/or its inhibitor osteoprotegerin (OPG). Further elucidation of the mechanisms responsible for inflammation-induced bone loss will potentially lead to the identification of novel therapeutic strategies for the prevention of bone loss in these diseases. In this review, we provide an overview of the cell types, inflammatory mediators, and mechanisms that are implicated in bone loss and new bone formation in inflammatory joint diseases.
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Affiliation(s)
- Nicole C Walsh
- Beth Israel Deaconess Medical Center, New England Baptist Bone and Joint Institute, Harvard Institutes of Medicine, Boston, MA 02115, USA
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21
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Shen CL, Yeh JK, Wang X. Short-term supplementation of COX-2 inhibitor suppresses bone turnover in gonad-intact middle-aged male rats. J Bone Miner Metab 2006; 24:461-6. [PMID: 17072738 DOI: 10.1007/s00774-006-0709-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2006] [Accepted: 05/31/2006] [Indexed: 12/13/2022]
Abstract
There is an increasing body of evidence supporting the idea that nonsteroidal antiinflammatory drugs can effectively suppress ovariectomy-induced bone loss in adult rats. The present study investigated the effects of supplementation of selective cyclooxygenase-2 inhibitor [5,5-dimethyl-3-(3 flurophenyl)-4-(4 methylsulphonal) phenyl-2 (6H) furanone, DFU] to diets on bone metabolism, bone mineral density (BMD), and histomorphometry in middle-aged male rats. Forty 16-month-old male rats (n = 8/group) were fed diets containing 0 (control), 5, 10, 15, or 20 mg/kg DFU body weight/day for 4 weeks. Supplementation of DFU resulted in higher plasma levels of pyridinoline, insulin-like growth factor I, and parathyroid hormone, but lower bone-specific alkaline phosphatase activity, prostaglandin E(2,) and 1,25-(OH)(2) vitamin D(3). Compared to the control, DFU supplementation at 20 mg/kg did not affect total scanned area, BMD, and bone mineral content as determined by DEXA. Histomorphometric data showed that rats fed DFU at 20 mg/kg had lower values of mineralizing surface, eroded surface, mineral apposition rate, and bone formation rate, but no difference in trabecular thickness, number, and separation compared to the control. The present data demonstrate that the short-term supplementation of selective COX-2 inhibitor to gonad-intact middle-aged male rats resulted in suppression of bone formation and increased bone resorption, and thereby suppressed bone turnover rate, without significant loss of bone. Such action was through modulating local factors and systemic hormones.
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Affiliation(s)
- Chwan-Li Shen
- Department of Pathology, Texas Tech University Health Sciences Center, Lubbock, TX, 79430-9790, USA.
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22
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Coetzee M, Haag M, Claassen N, Kruger MC. Stimulation of prostaglandin E2 (PGE2) production by arachidonic acid, oestrogen and parathyroid hormone in MG-63 and MC3T3-E1 osteoblast-like cells. Prostaglandins Leukot Essent Fatty Acids 2005; 73:423-30. [PMID: 16198098 DOI: 10.1016/j.plefa.2005.08.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2005] [Revised: 08/08/2005] [Accepted: 08/11/2005] [Indexed: 11/12/2022]
Abstract
Polyunsaturated fatty acids (PUFAs) as well as oestrogen (E2) and parathyroid hormone (PTH) affect bone cells. The aim of the study was to determine whether arachidonic acid (AA), E2, and PTH increase prostaglandin E(2) (PGE(2)) synthesis in MG-63 and MC3T3-E1 osteoblastic cells and the level of mediation by COX-1 and COX-2. PGE(2) levels were determined in the conditioned culture media of MG-63 and MC3T3-E1 osteoblasts after exposure to AA, PTH and E2. Cells were pre-incubated in some experiments with the unselective COX inhibitor indomethacin or the COX-2 specific blocker NS-398. Indirect immunofluorescence was performed on MG-63 cells to detect the presence and location of the two enzymes involved. AA increased PGE(2) secretion in both cell lines; production by MC3T3-E1 cells, however, was significantly higher than that of MG-63 cells. This could be due to autoamplification via the EP(1) subtype of PGE receptors in mouse MC3T3-E1 osteoblasts. Both COX-1 and COX-2 affected the regulation of PGE(2) synthesis in MG-63 cells. E2 had no effect on PGE(2) secretion in both cell lines, while PTH caused a slight increase in PGE(2) synthesis in the MG-63 cell line.
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Affiliation(s)
- M Coetzee
- Department of Physiology, University of Pretoria, South Africa
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23
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Xu M, Choudhary S, Goltzman D, Ledgard F, Adams D, Gronowicz G, Koczon-Jaremko B, Raisz L, Pilbeam C. Do cyclooxygenase-2 knockout mice have primary hyperparathyroidism? Endocrinology 2005; 146:1843-53. [PMID: 15625247 DOI: 10.1210/en.2004-0734] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The absence of cyclooxygenase-2 (COX-2) activity in vitro reduces differentiation of both bone-forming and bone-resorbing cells. To examine the balance of COX-2 effects on bone in vivo, we studied COX-2 knockout (KO) and wild-type (WT) mice. After weaning, KO mice died 4 times faster than WT mice, consistent with reports of progressive renal failure in KO mice. Among KO mice killed at 4 months of age, some had renal failure with marked secondary hyperparathyroidism, but others appeared healthy. On the assumption that renal failure was not inevitable in COX-2 KO mice and that phenotypic differences might increase with age, we studied KO mice surviving to 10 months of age with serum creatinine levels similar to those of WT mice. In 10-month-old male KO mice, serum calcium and PTH, but not phosphorus, levels were increased compared with those in WT mice. 1,25-Dihydroxyvitamin D(3) levels were markedly elevated in KO mice. Skeletal analysis showed small nonsignificant decreases in cortical bone density by BMD and either an increase (distal femur, by microcomputed tomography) or no difference (distal femur, by static histomorphometry) in trabecular bone density in KO mice. There was a trend toward increased percent osteoblastic and osteoclastic surfaces, and on dynamic histomorphometry, the rates of trabecular bone formation and mineral apposition were increased in KO mice relative to WT mice. Similar trends were observed for most parameters in 10-month-old female COX-2 KO mice. However, rates of trabecular bone formation and mineral apposition were increased in 10-month-old WT females compared with males and did not increase further in female KO mice. These data suggest that COX-2 KO mice with intact renal function have primary hyperparathyroidism, and that effects of increased PTH and 1,25-dihydroxyvitamin D(3) to increase bone turnover may compensate for the absence of COX-2.
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Affiliation(s)
- Manshan Xu
- Department of Medicine, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, Connecticut 06030, USA
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24
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25
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Abstract
Bone undergoes a constant process of remodeling in which mass is retained or lost in response to the relative activity of osteoblasts and osteoclasts. Weight-bearing exercise-which is critical for retaining skeletal integrity-promotes osteoblast function, whereas a lack of mechanical stimulation, as seen during spaceflight or prolonged bed rest, can lead to osteoporosis. Thus, understanding mechanotransduction at the cellular level is key to understanding basic bone biology and devising new treatments for osteoporosis. Various mechanical stimuli have been studied as in vitro model systems and have been shown to act through numerous signaling pathways to promote osteoblast activity. Here, we examine the various types of stress and the sequential response of transduction pathways that result in changes in gene expression and the ensuing proliferation of osteoblasts.
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Affiliation(s)
- Millie Hughes-Fulford
- Laboratory of Cell Growth, Department of Medicine, Veterans Affairs Medical Center, University of California, and Northern California Institute for Research and Education, San Francisco, CA 94121, USA.
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26
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Tanaka M, Sakai A, Uchida S, Tanaka S, Nagashima M, Katayama T, Yamaguchi K, Nakamura T. Prostaglandin E2 receptor (EP4) selective agonist (ONO-4819.CD) accelerates bone repair of femoral cortex after drill-hole injury associated with local upregulation of bone turnover in mature rats. Bone 2004; 34:940-8. [PMID: 15193540 DOI: 10.1016/j.bone.2004.01.002] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Prostaglandin E(2) (PGE(2)) is essential for fracture healing. Systemic administration of EP4 ligands such as PGE(2) and other synthetic EP4 agonists appears to transduce anabolic signals by binding to receptor EP4. Therefore, the present study was designed to test whether administration of EP4 agonist accelerates the healing of drill-hole injury in the femoral diaphysis. After surgery, a total of 128 Wistar rats, at the age of 12 weeks, were assigned to basal control (n = 8), and three groups with respective doses of 0 (vehicle control), 10 (low-dose), and 30 (high-dose) microg/kg body weight of the agent were subcutaneously injected twice a day. Femoral specimens were obtained at 0, 5, 7, 14, 21, and 28 days. In EP4 agonist-treated groups, the total bone volume of the regenerating bone in the defect did not significantly differ, but the regenerated cortical bone volume measured by histomorphometry and cortical bone mineral content (Ct. BMC) by pQCT dose-dependently increased at 14 and 21 days compared to the control. In the high-dose group, the value of osteoclast surface significantly increased compared with that in the control at 14 days. Expression levels of osteocalcin and TRAP mRNAs in the injured tissue increased at 14 days. Expression levels of EP4, BMP-2, and RANKL mRNAs increased at 7 days in the high-dose group. The bone mineral values of the lumbar bone at 28 days, measured by DXA, did not differ in the three groups. These data indicated that systemic administration of EP4 agonist ONO-4819.CD accelerated cortical bone healing after drill-hole injury by upregulating the local turnover of the regenerating bone.
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Affiliation(s)
- Masahiro Tanaka
- Department of Orthopaedic Surgery, School of Medicine, University of Occupational and Environmental Health, Yahatanishi, Kitakyushu, Japan
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27
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Sakuma Y, Li Z, Pilbeam CC, Alander CB, Chikazu D, Kawaguchi H, Raisz LG. Stimulation of cAMP production and cyclooxygenase-2 by prostaglandin E(2) and selective prostaglandin receptor agonists in murine osteoblastic cells. Bone 2004; 34:827-34. [PMID: 15121014 DOI: 10.1016/j.bone.2003.12.007] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2003] [Accepted: 12/04/2003] [Indexed: 11/21/2022]
Abstract
Prostaglandins (PGs), particularly PGE(2), can stimulate bone resorption and formation and auto-amplify their effects by inducing cyclooxygenase (COX)-2. We examined the role of different PG receptors in stimulating cAMP production and COX-2 expression in murine calvarial osteoblasts. Cells were obtained from PGE(2) receptor (EP2R and EP4R) wild-type and knockout (KO) mice and from mice transgenic for the COX-2 promoter fused to a luciferase reporter. We analyzed effects of selective agonists, EP2A and EP4A, for EP2R and EP4R, which mediate the increase in cAMP in response to PGE(2). We also tested agonists for other PGE(2) receptors (EP1A and EP3A) and for prostacyclin (IPA), prostaglandin D(2) (DPA), thromboxane (TPA), and prostaglandin F(2alpha) (FPA) receptors. PGE(2) and EP2A were the most effective stimulators of cAMP production. EP4A, IPA, and DPA produced smaller responses, and EP1A, EP3A, FPA, and TPA were ineffective. In EP2R KO cells, cAMP responses to PGE(2) were reduced by 80%, and responses to EP2A were abrogated. In EP4R KO cells, cAMP responses to PGE(2) and EP2A showed a small reduction, while the response to EP4A was abrogated. Pretreatment with PGE(2), EP2A, or EP4A down-regulated the subsequent response to the respective ligands. COX-2 induction was measured by increased luciferase activity and mRNA expression. PGE(2) was the most effective agonist; EP2A and another selective EP2R agonist, butaprost, showed similar efficacy, and EP4A was less effective. EP2A and EP4A effects on luciferase activity were additive, and effects of the combination were similar to PGE(2) itself. IPA, TPA, and DPA produced 2- to 6-fold increases in COX-2 expression. FPA was a weak agonist, while EP1A and EP3A were inactive. Treatment with specific inhibitors indicated that PGE(2), EP2A, and EP4A induced COX-2 expression largely through protein kinase A (PKA). We conclude that the PG induction of COX-2 in this system generally paralleled effects on cAMP production and was mediated predominantly via the PKA pathway.
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Affiliation(s)
- Yoko Sakuma
- Department of Medicine, University of Connecticut Health Center, Farmington, CT 06030, USA
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28
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Choudhary S, Wadhwa S, Raisz LG, Alander C, Pilbeam CC. Extracellular calcium is a potent inducer of cyclo-oxygenase-2 in murine osteoblasts through an ERK signaling pathway. J Bone Miner Res 2003; 18:1813-24. [PMID: 14584892 DOI: 10.1359/jbmr.2003.18.10.1813] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
UNLABELLED [Ca2+]e may be important in bone turnover. We found [Ca2+]e induces COX-2 transcription and PGE2 production in primary calvarial osteoblasts through an ERK signaling pathway. Inhibition of PGE2 production inhibited the [Ca2+]e stimulation of osteoblastic differentiation but not the increase in cell number. Hence, some effects of [Ca2+]e on bone may be mediated by COX-2. INTRODUCTION Local changes in extracellular calcium ([Ca2+]e) may play an important role in bone turnover. We examined the possibility that prostaglandins produced by cyclo-oxygenase-2 (COX-2) could mediate some of the effects of [Ca2+]e on osteoblasts. METHODS We examined the [Ca2+]e induction of COX-2 expression and prostaglandin E2 (PGE2) production in primary osteoblasts (POBs) obtained by sequential enzymatic digestion of mouse calvariae. We measured mRNA and protein levels by Northern and Western analyses and PGE2 production in culture medium by radioimmunoassay (RIA). COX-2 promoter activity was measured as luciferase activity in calvarial osteoblasts derived from mice transgenic for 371 bp of the COX-2 promoter fused to a luciferase reporter gene. RESULTS AND CONCLUSIONS COX-2 mRNA and protein expression were induced by 3-40 mM of [Ca2+]e. [Ca2+]e (5 mM) induced COX-2 mRNA within 30 minutes; levels peaked at 6-9 h and remained elevated at 24 h. Cumulative medium PGE2 was increased at 3 h, with levels rising to 30 nM at 24 h. PGE2 production in POBs from mice with only COX-1 gene expression was 1/40th of that in POBs from mice with both COX-1 and COX-2 gene expression. [Ca2+]e increased alkaline phosphatase activity and osteocalcin mRNA, and this increase was blocked by inhibiting PGE2 production. [Ca2+]e stimulation of COX-2 promoter activity correlated with the induction of COX-2 mRNA expression. [Ca2+]e induced rapid and transient phosphorylation of extracellular signal-regulated kinase (ERK) in POBs, which peaked at 5-10 minutes. Inhibition of ERK phosphorylation with the specific inhibitors, PD-98059 and U-0126, decreased the [Ca2+]e induction of both COX-2 mRNA and luciferase activity by 70-80%. Although less effective than [Ca2+]e, strontium [Sr2+]e also induced COX-2 mRNA and promoter activity in POBs through an ERK signaling pathway. We conclude that [Ca2+]e is a potent transcriptional inducer of COX-2 expression and PGE2 production in osteoblasts through an ERK signaling pathway.
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Affiliation(s)
- Shilpa Choudhary
- Department of Medicine, University of Connecticut Health Center, Farmington, Connecticut 06030, USA
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Kim CH, Kim YH, Kim YK, Kang BS, Lee TK, Moon SH, Park YG. IL-1beta induces and TGF-beta reduces vitamin D3-induced bone resorption in mouse calvarial bone cells. Immunol Invest 2003; 32:171-86. [PMID: 12916707 DOI: 10.1081/imm-120022977] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Bone cells produce multiple growth factors and cytokines that have effects on bone metabolism and can be incorporated into the bone matrix. The present study was designed to extend these observations by examining the interactions between transforming growth factor-beta (TGF-beta) or interleukin-1beta (IL-1beta) and bone cells in a rat long bone culture model. IL-1beta regulates several activities of the osteoblast cells derived from rat long bone explants in vitro. IL-1beta stimulated cellular proliferation and the synthesis of prostaglandin E2 and plasminogen activator activity in the cultured cells in a dose-dependent manner. TGF-B is present in the bone matrix and potentially can be released during bone resorption. TGF-beta reduced basal bone resorption and inhibited vitamin D3 [1,25(OH)2D3]-induced bone resorption in rat long bone cells. These studies support the role of IL-1beta in the pathological modulation of bone cell metabolism, with regard to implication in the pathogenesis of osteoporosis by IL-1beta, and that TGF-beta is positively inhibiting the bone resorption.
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Affiliation(s)
- Cheorl-Ho Kim
- National Research Laboratory for Glycobiology (NRLG), Korean Ministry of Science and Technology, Kyungju City, Kyungbuk, Korea.
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30
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Sung HH, Kao WY, Su YJ. Effects and toxicity of phthalate esters to hemocytes of giant freshwater prawn, Macrobrachium rosenbergii. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2003; 64:25-37. [PMID: 12763673 DOI: 10.1016/s0166-445x(03)00011-0] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Phthalate esters (PAEs) have been considered as environmental pollutants and have been subject to control in the United States of America and Japan. The aim of this study was to investigate the effects and toxicity of eight PAEs to hemocytes and the defense functions of giant freshwater prawn (Macrobrachium rosenbergii), including hemocytic adhesion, pseudopodia formation, phenoloxidase (PO) activity, and superoxide anion (O(2)(-)) production, by means of in vitro exposure experiments. After hemocytes were treated separately with eight PAEs at concentrations of 100 microg/ml, the results showed that two PAEs (dipropyl phthalate, DPrP and diethyl phthalate, DEP) increased cells with pseudopodia formation, but decreased adhesive cells; reduction in the percentages of both pseudopodia formation and adhesive cells were detected in the dihexyl phthalate (DHP) and diphenyl phthalate (DPP) experiment groups; and di-(2-ethyl hexyl) phthalate (DEHP) decreased pseudopodia formation, but did not affect the adhesion. In addition, both PO activity and O(2)(-) production were decreased after hemocytes were treated with five PAEs (benzyl butyl phthalate (BBP), di-n-butyl phthalate (DBP), DEP, DHP and DPrP), respectively. At the same time, microscopy showed that both DPrP and DHP altered morphology of the cell nucleus and led to the presence of vacuoles in cytosol of hemocytes. Using the annexin assay, and after analysis of DNA fragmentation and transmission electron microscopy (TEM), it was found that hemocytes exposed to DHP and DPrP for more than 10 min would primarily die via apoptosis, the fatality correlates with increasing treatment time; and hemocytes treated with either BBP, dicyclohexyl phthalate (DCP), DEP or DPP would primarily die via necrosis. According to these results, we suggest that all eight PAEs examined could damage hemocytes and further influence the defense mechanism of prawns. This study reveals an important precaution for prawn cultivation.
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Affiliation(s)
- Hung-Hung Sung
- Department of Microbiology, Soochow University, Taipei 111, Taiwan, ROC.
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31
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Chang JK, Chuang LY, Ho ML, Wang GJ. Effects of nonsteroidal anti-inflammatory drugs on transforming growth factor-beta expression and bioactivity in rat osteoblast-enriched culture. Kaohsiung J Med Sci 2003; 19:278-88. [PMID: 12873036 DOI: 10.1016/s1607-551x(09)70474-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Nonsteroidal anti-inflammatory drugs (NSAIDs) have been reported to suppress bone remodeling in normal and repaired bones. Our previous results indicated that ketorolac and indomethacin suppressed proliferation, stimulated early differentiation, and induced apoptosis in cultured osteoblasts. Transforming growth factor-beta (TGF-beta) has been reported to enhance proliferation, suppress differentiation, and prevent apoptosis in osteoblasts. We proposed that one pathway of NSAID effects on osteoblast function might be through inhibition of the expression and/or bioactivity of TGF-beta in osteoblasts. We tested the effects of ketorolac and indomethacin on the expression of TGF-beta1 mRNA and protein and the bioactivity of TGF-beta in osteoblast-enriched cultures derived from fetal calvaria. The effects of prostaglandin E1 (PGE1) and PGE2 on TGF-beta expression and bioactivity were also examined in order to understand more about the role of prostaglandins in osteoblast function. Simultaneously, we estimated whether these NSAID effects on osteoblasts were prostaglandin-related. The results showed that 24-hour treatments with both PGEs and theoretic therapeutic concentrations of ketorolac and indomethacin had no significant effects on the levels of either transcription or translation of TGF-beta or the post-translational function of TGF-beta in osteoblasts. These results suggest that NSAIDs do not affect osteoblast function through changes in TGF-beta action in osteoblasts.
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Affiliation(s)
- Je-Ken Chang
- Department of Orthopedics, School of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
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32
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Debey S, Meyer-Kirchrath J, Schrör K. Regulation of cyclooxygenase-2 expression by iloprost in human vascular smooth muscle cells. Role of transcription factors CREB and ICER. Biochem Pharmacol 2003; 65:979-88. [PMID: 12623129 DOI: 10.1016/s0006-2952(02)01661-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Prostaglandin-endoperoxide synthase-2 (PGH-synthase) or cyclooxygenase-2 (COX-2) is inducible by a variety of stimuli, e.g. inflammatory mediators, growth factors and hormones and is believed to be responsible for the majority of inflammatory prostanoid production. Moreover, it has been demonstrated that COX-2 contributes substantially to prostacyclin-synthesis in patients with atherosclerosis. In this study, we demonstrate an up-regulation of COX-2 mRNA, protein and product formation by the prostacyclin-mimetic iloprost in human vascular smooth muscle cells (hSMC). COX-2 mRNA expression was induced transiently between 1 and 6 hr and returned to basal levels after 16 hr of iloprost stimulation. COX-2 protein was induced concomitantly between 3 and 6 hr of iloprost stimulation. This was accompanied by an increase in PGI(2) formation. Forskolin, a direct activator of adenylyl cyclase, and dibutyryl cAMP, a cell-permeable cAMP analogue-induced COX-2 mRNA, suggesting a cAMP-dependent COX-2 expression in hSMC. Iloprost-induced COX-2 protein expression and PGI(2) formation was synergistically elevated by co-stimulation with the phorbolester PMA (phorbol-12-myristate-13-acetate). It is concluded, that the observed up-regulation of COX-2 with subsequent release of newly synthesized PGI(2) and the synergistic effect of iloprost and phorbolester on PGI(2) formation provide a positive feedback of prostaglandins on their own synthesizing enzyme. This might be important for control of hSMC proliferation, migration and differentiation as well as inhibition of platelet aggregation.
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Affiliation(s)
- Svenja Debey
- Institut für Pharmakologie und Klinische Pharmakologie, Universitäts Klinikum Düsseldorf, Heinrich-Heine-Universität, Moorenstrasse 5, D-40225 Düsseldorf, Germany
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Naruse K, Miyauchi A, Itoman M, Mikuni-Takagaki Y. Distinct anabolic response of osteoblast to low-intensity pulsed ultrasound. J Bone Miner Res 2003; 18:360-9. [PMID: 12568414 DOI: 10.1359/jbmr.2003.18.2.360] [Citation(s) in RCA: 134] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Low-intensity pulsed ultrasound, a form of mechanical energy transmitted as high-frequency acoustical pressure waves, provides noninvasive therapeutic treatment for accelerating fracture repair and distraction osteogenesis. Relatively young osteoblasts respond to ultrasound by transiently upregulating message levels of immediate-early genes as well as that of osteocalcin and insulin-like growth factor I (IGF-I). Osteocytes derived from newborn rat tibia and calvaria responded to a lesser extent only in c-fos and cyclooxygenase-2 (COX-2) messages. Compared with the stretched osteocytes, which use stretch-activated and parathyroid hormone (PTH)-potentiated Ca2+ influx as an entry route to the protein kinase A (PKA) signal transduction pathways, there was no evidence of Ca2+ internalization by any of the cells tested on exposure to the ultrasound. On the other hand, inhibitors of p38 mitogen-activated protein kinase (MAPK) and upstream phosphoinositide 3-kinase (PI3K) blocked COX-2 and osteocalcin upregulation by the ultrasound-exposed ST2, murine bone marrow-derived cells. This is distinct from the aforementioned osteocytic response to low-frequency stretching and implies the involvement of integrins. Our findings suggested that accelerated fracture repair and distraction osteogenesis by the low-intensity pulsed ultrasound depend, at least in part, on the stimulation of osteoblastic cells at relatively early stages of osteogenic lineage. Bone is under control of multiple regulatory mechanisms so that diverse physical forces can be reflected to the microenvironment of each cell, in turn, to the entire bone.
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Affiliation(s)
- Kouji Naruse
- Department of Orthopedic Surgery, Kitasato University School of Medicine, Sagamihara, Japan
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34
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Wadhwa S, Choudhary S, Voznesensky M, Epstein M, Raisz L, Pilbeam C. Fluid flow induces COX-2 expression in MC3T3-E1 osteoblasts via a PKA signaling pathway. Biochem Biophys Res Commun 2002; 297:46-51. [PMID: 12220506 DOI: 10.1016/s0006-291x(02)02124-1] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Mechanical loading of bone generates fluid flow within the mineralized matrix which can exert fluid shear stress (FSS) at cell membranes. FSS induces new transcription of cyclooxygenase-2 (COX-2) in MC3T3-E1 osteoblasts, with peak effects at 4-5h. Using MC3T3-E1 cells stably transfected with the COX-2 promoter fused to a luciferase reporter, we examined involvement of the protein kinase A (PKA) and protein kinase C (PKC) signaling pathways in the peak COX-2 mRNA and luciferase responses to FSS (10dyn/cm(2)). Neither inhibition nor down-regulation of the PKC pathway affected the FSS stimulation of COX-2 mRNA or luciferase activity. In contrast, inhibitors of the PKA pathway, used at doses which inhibited forskolin-stimulated luciferase activity by 70-80%, reduced FSS-stimulated COX-2 mRNA expression and luciferase activity by 50-80%. Hence, peak FSS induction of COX-2 expression in MC3T3-E1 osteoblastic cells is largely dependent on the PKA signaling pathway.
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Affiliation(s)
- Sunil Wadhwa
- Department of Orthodontics, School of Dental Medicine, University of Connecticut Health Center, Farmington, CT 06030, USA
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35
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Kim CH, Kang BS, Lee TK, Park WH, Kim JK, Park YG, Kim HM, Lee YC. IL-1beta regulates cellular proliferation, prostaglandin E2 synthesis, plasminogen activator activity, osteocalcin production, and bone resorptive activity of the mouse calvarial bone cells. Immunopharmacol Immunotoxicol 2002; 24:395-407. [PMID: 12375736 DOI: 10.1081/iph-120014725] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Interleukin-1beta (IL-1beta) regulates several activities of the osteoblast cells derived from mouse calvarial bone explants in vitro. IL-1beta stimulated cellular proliferation and the synthesis of prostaglandin E2 in the cultured cells in a dose-dependent manner. Furthermore, plasminogen activator activity of the mouse osteoblast was positively affected by IL-1beta in a dose-dependent manner over the dosage range of 0.01 ng-2 ng/mL with a maximal effect being observed at 2 ng/mL. However, the induction of osteocalcin synthesis and alkaline phosphatase activity in response to vitamin D, two characteristics of the osteoblast phenotype, were significantly antagonized by IL-1beta over a similar dose range. Treatment of mouse calvarial bone cells with IL-1beta resulted in a dose dependent stimulation of bone resorption and the bone resorption induced by IL-1beta was strongly inhibited by calcitonin treatment, indicating osteoclast-mediated bone resorption, suggesting that the bone resorption induced by IL-1beta appears to be osteoclast-mediated. This study supports the role of IL-1beta in the pathological modulation of bone cell metabolism, with regard to implication of the pathogenesis of osteoporosis by IL-1beta.
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Affiliation(s)
- Cheorl-Ho Kim
- Department of Biochemistry and Molecular Biology, College of Oriental Medicine, Dongguk University, Kyungju City, Kyungbuk, Korea.
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36
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Kanda N, Watanabe S. Ketoconazole suppresses prostaglandin E(2)-induced cyclooxygenase-2 expression in human epidermoid carcinoma A-431 cells. J Invest Dermatol 2002; 119:174-81. [PMID: 12164941 DOI: 10.1046/j.1523-1747.2002.01804.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Cyclooxygenase-2 is a key enzyme in the conversion of arachidonic acid to prostaglandins. The overexpression of cyclooxygenase-2 has been reported in skin cancer cells, and may be involved in carcinogenesis. Prostaglandin E2, the end product of cyclooxygenase-2-induced catalysis, autoamplifies the cyclooxygenase-2 expression. It is suggested that an anti-mycotic drug, ketoconazole may inhibit carcinogenesis. We herein investigated if ketoconazole may inhibit prostaglandin E2-induced cyclooxygenase-2 expression in human epidermoid carcinoma A-431 cells. Ketoconazole suppressed prostaglandin E2-induced cyclooxygenase-2 protein and mRNA expression and promoter activation in A-431; the suppressive effects of ketoconazole were counteracted by cyclic adenosine monophosphate analog. Analyses using deleted or mutated cyclooxygenase-2 promoters revealed that cyclic adenosine monophosphate response element (- 59 to - 53 bp) on the promoter was involved in prostaglandin E2-induced stimulation and ketoconazole-induced inhibition of the promoter activity. Electrophoretic mobility shift assays indicated that cyclic adenosine monophosphate response element binding protein and activating transcription factor-1 may constitutively bind to cyclic adenosine monophosphate response element on cyclooxygenase-2 promoter. Prostaglandin E2 increased the proportion of phosphorylated forms among total bound cyclic adenosine monophosphate response element binding protein/activating transcription factor-1, and the effect was suppressed by ketoconazole. Prostaglandin E2 induced the phosphorylation of cyclic adenosine monophosphate response element binding protein and activating transcription factor-1, and the phosphorylation was suppressed by cyclic adenosine monophosphate-dependent protein kinase (protein kinase A) inhibitor, indicating protein kinase A-mediated phosphorylation. Ketoconazole suppressed the prostaglandin E2-induced phosphorylation of cyclic adenosine monophosphate response element binding protein/activating transcription factor-1. Prostaglandin E2 increased intracellular cyclic adenosine monophosphate level by activating adenylate cyclase in A-431, and the increase was suppressed by ketoconazole. These results suggest that ketoconazole may suppress prostaglandin E2-induced cyclooxygenase-2 expression by inhibiting the cyclic adenosine monophosphate signal in A-431, and stress its anti-cancer effect.
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Affiliation(s)
- Naoko Kanda
- Department of Dermatology, Teikyo University, School of Medicine, 11-1 Kaga-2, Itabashi-Ku, Tokyo 173-8605, Japan.
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37
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Igarashi K, Woo JT, Stern PH. Effects of a selective cyclooxygenase-2 inhibitor, celecoxib, on bone resorption and osteoclastogenesis in vitro. Biochem Pharmacol 2002; 63:523-32. [PMID: 11853703 DOI: 10.1016/s0006-2952(01)00861-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The effects of an important new anti-inflammatory agent, the selective cyclooxygenase-2 inhibitor celecoxib, on bone resorption and osteoclastogenesis elicited by the inflammatory cytokines interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha), the endotoxin lipopolysaccharide (LPS), and the systemic hormones 1alpha,25-dihydroxyvitamin D(3) and parathyroid hormone were examined in vitro. Bone resorption was evaluated by measuring calcium released into the culture medium in a neonatal mouse calvarial bone organ culture. Osteoclastogenesis was evaluated by measuring tartrate-resistant acid phosphatase activity in the cells in cocultures of bone marrow cells and osteoblastic cells and in macrophage-colony-stimulating factor-dependent bone marrow cell cultures. Celecoxib (0.1 microM) completely inhibited the calcium release induced by IL-1beta, TNF-alpha, and LPS. The resorptive effect of 1alpha,25-dihydroxyvitamin D(3) was inhibited partially by celecoxib. In contrast, celecoxib did not inhibit the calcium release elicited by parathyroid hormone or prostaglandin E(2). Celecoxib (0.1 microM) also markedly inhibited osteoclastogenesis induced by these stimulators of bone resorption except for PGE(2) in the coculture system, whereas it failed to inhibit osteoclastogenesis in macrophage-colony-stimulating factor-dependent bone marrow cell cultures. These results indicate that, under certain conditions, cyclooxygenase-2-dependent prostaglandin synthesis is critical for the bone resorption induced by IL-1beta, TNF-alpha, and LPS, and for the osteoclastogenesis induced by these pro-inflammatory molecules and calciotropic hormones. The prevention of prostaglandin synthesis by inflammatory cytokines in bone cells could contribute to the efficacy of celecoxib in preventing bone loss in rheumatoid arthritis.
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Affiliation(s)
- Kaoru Igarashi
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, 303 E. Chicago Avenue, Chicago, IL 60611, USA
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38
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Wadhwa S, Godwin SL, Peterson DR, Epstein MA, Raisz LG, Pilbeam CC. Fluid flow induction of cyclo-oxygenase 2 gene expression in osteoblasts is dependent on an extracellular signal-regulated kinase signaling pathway. J Bone Miner Res 2002; 17:266-74. [PMID: 11811557 DOI: 10.1359/jbmr.2002.17.2.266] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Mechanical loading of bone may be transmitted to osteocytes and osteoblasts via shear stresses at cell surfaces generated by the flow of interstitial fluid. The stimulated production of prostaglandins, which mediates some effects of mechanical loading on bone, is dependent on inducible cyclo-oxygenase 2 (COX-2) in bone cells. We examined the fluid shear stress (FSS) induction of COX-2 gene expression in immortalized MC3T3-E1 osteoblastic cells stably transfected with -371/+70 base pairs (bp) of the COX-2 5'-flanking DNA (Pluc371) and in primary osteoblasts (POBs) from calvaria of mice transgenic for Pluc371. Cells were plated on collagen-coated glass slides and subjected to steady laminar FSS in a parallel plate flow chamber. FSS, from 0.14 to 10 dynes/cm2, induced COX-2 messenger RNA (mRNA) and protein. FSS (10 dynes/cm2) induced COX-2 mRNA within 30 minutes, with peak effects at 4 h in MC3T3-E1 cells and at > or = 8 h in POBs. An inhibitor of new protein synthesis puromycin blocked the peak induction of COX-2 mRNA by FSS. COX-2 promoter activity, measured as luciferase activity, correlated with COX-2 mRNA expression in both MC3T3-E1 and POB cells. FSS induced phosphorylation of extracellular signal-regulated kinase (ERK) in MC3T3-E1 cells, with peak effects at 5 minutes. Inhibiting ERK phosphorylation with the specific inhibitor PD98059 inhibited FSS induction of COX-2 mRNA by 55-70% and FSS stimulation of luciferase activity by > or = 80% in both MC3T3-E1 and POB cells. We conclude that FSS transcriptionally induces COX-2 gene expression in osteoblasts, that the maximum induction requires new protein synthesis, and that induction occurs largely via an ERK signaling pathway.
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Affiliation(s)
- Sunil Wadhwa
- Department of Orthodontics, School of Dental Medicine, University of Connecticut Health Center, Farmington 06030, USA
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39
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Chikazu D, Katagiri M, Ogasawara T, Ogata N, Shimoaka T, Takato T, Nakamura K, Kawaguchi H. Regulation of osteoclast differentiation by fibroblast growth factor 2: stimulation of receptor activator of nuclear factor kappaB ligand/osteoclast differentiation factor expression in osteoblasts and inhibition of macrophage colony-stimulating factor function in osteoclast precursors. J Bone Miner Res 2001; 16:2074-81. [PMID: 11697804 DOI: 10.1359/jbmr.2001.16.11.2074] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
This study investigated the mechanism of direct and indirect actions of fibroblast growth factor 2 (FGF-2) on osteoclast differentiation using two mouse cell culture systems. In the coculture system of osteoblasts and bone marrow cells, FGF-2 stimulated osteoclast formation. This effect was decreased markedly by osteoprotegerin (OPG) or NS-398, a selective cyclo-oxygenase 2 (COX-2) inhibitor. FGF-2 (> or = 10(-9) M) stimulated receptor activator of nuclear factor kappaB ligand/osteoclast differentiation factor (RANKL/ODF) messenger RNA (mRNA) expression from 2 h to 7 days in cultured osteoblasts. NS-398 did not affect the early induction but decreased the later one, indicating that the later effect is mediated by COX-2 induction in osteoblasts. To study the direct action of FGF-2 on osteoclast precursors, we used mouse macrophage-like cell line C7 cells that can differentiate into osteoclasts in the presence of soluble RANKL/ODF (sRANKL/ODF) and macrophage colony-stimulating factor (M-CSF). Although osteoblasts expressed all FGF receptors (FGFR-1 to -4), only FGFR-1 was detected in C7 cells at various differentiation stages. FGF-2 alone or in combination with sRANKL/ODF did not induce osteoclastogenesis from C7 cells; however, FGF-2 from lower concentrations (> or = 10(-11) M) significantly decreased osteoclast formation induced by M-CSF in the presence of sRANKL/ODF. FGF-2 did not alter mRNA levels of M-CSF receptor (Fms) or RANK in C7 cells. Immunoprecipitation/ immunoblotting analyses revealed that tyrosine phosphorylation of several cellular proteins including Fms in C7 cells induced by M-CSF was inhibited by FGF-2 in the presence of sRANKL/ODF. We conclude that FGF-2 regulates osteoclast differentiation through two different mechanisms: (1) an indirect stimulatory action via osteoblasts to induce RANKL/ODF partly through COX-2 induction and prostaglandin production and (2) a direct inhibitory action on osteoclast precursors by counteracting M-CSF signaling.
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Affiliation(s)
- D Chikazu
- Department of Orthopedic Surgery, Graduate School of Medicine, University of Tokyo, Japan
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40
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Warden SJ, Favaloro JM, Bennell KL, McMeeken JM, Ng KW, Zajac JD, Wark JD. Low-intensity pulsed ultrasound stimulates a bone-forming response in UMR-106 cells. Biochem Biophys Res Commun 2001; 286:443-50. [PMID: 11511078 DOI: 10.1006/bbrc.2001.5412] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Low-intensity (<100 mW/cm(2)) pulsed ultrasound (US) is an established therapy for fracture repair. In both animal and human trials, such US has been shown to facilitate fresh fracture repair and initiate healing in fractures with repair defects. However, the mechanism by which US achieves these outcomes is not clear. One possible mechanism is the direct stimulation of bone formation. To investigate this hypothesis, the current study investigated the mRNA response of isolated bone-forming cells (UMR-106 cells) to a single 20-min dose of low-intensity pulsed US. Using a novel US-cell coupling method, US was found to stimulate expression of the immediate-early response genes c-fos and COX-2 and elevate mRNA levels for the bone matrix proteins ALP and OC. These findings suggest that low-intensity pulsed US has a direct effect on bone formation. This may contribute to the beneficial effect of low-intensity pulsed US on fracture repair.
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Affiliation(s)
- S J Warden
- Centre for Sports Medicine Research and Education, School of Physiotherapy, University of Melbourne, Melbourne, Victoria, Australia
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41
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Cheng B, Kato Y, Zhao S, Luo J, Sprague E, Bonewald LF, Jiang JX. PGE(2) is essential for gap junction-mediated intercellular communication between osteocyte-like MLO-Y4 cells in response to mechanical strain. Endocrinology 2001; 142:3464-73. [PMID: 11459792 DOI: 10.1210/endo.142.8.8338] [Citation(s) in RCA: 134] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We have observed, in our previous studies, that fluid flow increases gap junction-mediated intercellular coupling and the expression of a gap junction protein, connexin 43, in osteocyte-like MLO-Y4 cells. Interestingly, this stimulation is further enhanced during the poststress period, indicating that a released factor(s) is likely to be involved. Here, we report that the conditioned medium obtained from the fluid flow-treated MLO-Y4 cells increased the number of functional gap junctions and connexin 43 protein. These changes are similar to those observed in MLO-Y4 cells directly exposed to fluid flow. Fluid flow was found to induce PGE(2) release and increase cyclooxygenase 2 expression. Treatment of the cells with PGE(2) had the same effect as fluid flow, suggesting that PGE(2) could be responsible for these autocrine effects. When PGE(2) was depleted from the fluid flow-conditioned medium, the stimulatory effect on gap junctions was partially, but significantly, decreased. Addition of the cyclooxygenase inhibitor, indomethacin, partially blocked the stimulatory effects of mechanical strain on gap junctions. Taken together, these studies suggest that the stimulatory effect of fluid flow on gap junctions is mediated, in part, by the release of PGE(2). Hence, PGE(2) is an essential mediator between mechanical strain and gap junctions in osteocyte-like cells.
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Affiliation(s)
- B Cheng
- Department of Biochemistry, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900, USA
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42
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Gardner CR, Blanqué R, Cottereaux C. Mechanisms involved in prostaglandin-induced increase in bone resorption in neonatal mouse calvaria. Prostaglandins Leukot Essent Fatty Acids 2001; 64:117-25. [PMID: 11237479 DOI: 10.1054/plef.2001.0250] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Prostaglandins (PG) E1, E2 and F2alpha induce bone resorption in isolated neonatal parietal bone cultures, and an associated increase in interleukin-6 (IL-6) production. Indomethacin had little effect on the response to PGE2, or the relatively non-selective EP receptor agonists 11-deoxy PGE1 and misoprostol, but blocked the effects of PGF2alpha and the F receptor agonist fluprostenol, indicating an indirect action via release of other prostaglandins. It is more likely that there is positive autoregulation of prostaglandins production in this preparation mediated via stimulation of F receptors. The effects of selective EP receptor agonists sulprostone (EP1,3) and 17-phenyl trinor PGE2(EP1), indicated the involvement of EP2 and/or EP4 receptors, which signal via cAMP. The relatively weak increase in IL-6 production by misoprostol (with respect to resorption) suggests that these responses are controlled by different combination of EP2 and EP4 receptors. The PKA activator, forskolin, induced small increases in bone resorption at lower concentrations (50-500 ng/ml) but a reversal of this effect, and inhibition of resorption induced by other stimuli (PTH, PGE2), at higher concentrations (0.5-5 microg/ml). IL-6 production was markedly increased only at the higher concentrations. The inhibitory effect of forskolin may be a calcitonin-mimetic effect. PMA induced both resorption and IL-6 production which were both blocked by indomethacin, indicating a role for PKC in the control of prostaglandin production.
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Affiliation(s)
- C R Gardner
- Hoechst Marion Roussel Research Centre, 102 route de Noisy, Romainville, 93235, France.
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43
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Pavan B, Biondi C, Ferretti ME, Lunghi L, Paganetto G. Phthalic acid mimics 17beta-estradiol actions in WISH cells. Toxicol Lett 2001; 118:157-64. [PMID: 11137322 DOI: 10.1016/s0378-4274(00)00279-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The object of this study was to evaluate whether phthalic acid, which is one of the metabolites of phthalic acid esters, exerts estrogenic actions in WISH cells, an immortalized cell line derived from human amniotic tissue. Our data demonstrate that phthalic acid (i) displaces [3H]estradiol from its binding sites, (ii) enhances the intracellular cyclic AMP concentration, without influencing adenylyl cyclase activity, (iii) stimulates or inhibits prostaglandin output, probably depending on the intracellular nucleotide level. The effects on prostanoid release are counteracted by addition of the protein-synthesis inhibitor cycloheximide, or when the diffusion of phthalic acid through the cell membrane is prevented. On the basis of our previous demonstration, that 17beta-estradiol exerts similar effects in WISH cells, we suggest that the molecular mechanisms underlying phthalic acid and steroid-hormone responses in this cell line are the same. This is the first demonstration that phthalic acid binds to the estrogen receptor with high affinity and mimics the hormone physiological actions.
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Affiliation(s)
- B Pavan
- Section of General Physiology, Department of Biology, University of Ferrara, via Luigi Borsari 46, 44100-I, Ferrara, Italy
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44
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Bonazzi A, Bolla M, Buccellati C, Hernandez A, Zarini S, Viganò T, Fumagalli F, Viappiani S, Ravasi S, Zannini P, Chiesa G, Folco G, Sala A. Effect of endogenous and exogenous prostaglandin E(2) on interleukin-1 beta-induced cyclooxygenase-2 expression in human airway smooth-muscle cells. Am J Respir Crit Care Med 2000; 162:2272-7. [PMID: 11112151 DOI: 10.1164/ajrccm.162.6.2003127] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
We studied the effect of endogenous and exogenous prostaglandin E(2) (PGE(2)), a metabolite of arachidonic acid through the cyclooxygenase (COX) pathway, on interleukin (IL)-1 beta-induced COX-2 expression, using primary cultures of human bronchial smooth-muscle cells (HBSMC). Treatment with exogenous PGE(2) resulted in enhanced expression of IL-1 beta-induced COX-2 protein and messenger RNA (mRNA) as compared with the effect of the cytokine per se. Inhibition of PGE(2) production with a nonselective COX inhibitor (flurbiprofen, 10 microM) resulted in a significant reduction in IL-1 beta- induced COX-2 expression, supporting a role of endogenous COX metabolites in the modulation of COX-2 expression. None of the experimental conditions used in the study affected the expression of constitutive cyclooxygenase (COX-1). Treatment with cycloheximide to inhibit translation, and with dexamethasone or actinomycin D to inhibit transcription, linked the effect of PGE(2) to the transcriptional level of COX-2 mRNA rather than to a potential effect on protein and/or mRNA stabilization. PGE(2) increased adenylate cyclase activity in a concentration dependent manner, and forskolin, a direct activator of adenylate cyclase, caused a marked increase in IL-1 beta-dependent COX-2, suggesting the existence of a causal relationship between the two events. The same results were observed with salbutamol, a bronchodilator that acts by increasing cyclic adenosine monophosphate. The effect of PGE(2) on COX-2 expression may contribute to the hypothesized antiinflammatory role of PGE(2) in human airways, providing a self-amplifying loop leading to increased biosynthesis of PGE(2) during an inflammatory event.
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Affiliation(s)
- A Bonazzi
- Center for Cardiopulmonary Pharmacology, University of Milan, Milan, Italy
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45
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Okada Y, Voznesensky O, Herschman H, Harrison J, Pilbeam C. Identification of multiple cis-acting elements mediating the induction of prostaglandin G/H synthase-2 by phorbol ester in murine osteoblastic cells. J Cell Biochem 2000. [DOI: 10.1002/(sici)1097-4644(20000801)78:2<197::aid-jcb3>3.0.co;2-c] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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46
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Hinz B, Brune K, Pahl A. Prostaglandin E(2) upregulates cyclooxygenase-2 expression in lipopolysaccharide-stimulated RAW 264.7 macrophages. Biochem Biophys Res Commun 2000; 272:744-8. [PMID: 10860826 DOI: 10.1006/bbrc.2000.2859] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Prostaglandin E(2) (PGE(2)) has been implicated in the regulation of inflammatory and immunological events. Using RAW 264.7 macrophages, the present study investigates the influence of PGE(2) on the expression of cyclooxygenase-2 (COX-2). Incubation of cells with PGE(2) increased lipopolysaccharide (LPS)-induced COX-2 mRNA levels in a concentration-dependent manner. Upregulation of COX-2 expression by PGE(2) was completely abolished by the specific adenylyl cyclase inhibitor 2',5'-dideoxyadenosine and mimicked by butaprost, a selective agonist of the adenylyl cyclase-coupled PGE(2) receptor subtype 2 (EP(2)), or 11-deoxy PGE(1), an EP(2)/EP(4) receptor agonist. By contrast, the EP(3)/EP(1) receptor agonists 17-phenyl-omega-trinor PGE(2) and sulprostone left LPS-induced COX-2 expression virtually unaltered. Upregulation of LPS-induced COX-2 expression and subsequent PGE(2) synthesis was also observed in the presence of the cell-permeable cAMP analogue dibutyryl cAMP and the adenylyl cyclase activator cholera toxin. Together, our data demonstrate that PGE(2) potentiates COX-2 mRNA expression via an adenylyl cyclase/cAMP-dependent pathway. In conclusion, upregulation of COX-2 expression via an autocrine feed-forward loop may in part contribute to the well-known capacity of PGE(2)/cAMP to modulate inflammatory processes.
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Affiliation(s)
- B Hinz
- Department of Experimental and Clinical Pharmacology and Toxicology, Friedrich Alexander University Erlangen-Nürnberg, Germany.
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47
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Chen Y, Hughes-Fulford M. Prostaglandin E2 and the protein kinase A pathway mediate arachidonic acid induction of c-fos in human prostate cancer cells. Br J Cancer 2000; 82:2000-6. [PMID: 10864209 PMCID: PMC2363249 DOI: 10.1054/bjoc.2000.1143] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Arachidonic acid (AA) is the precursor for prostaglandin E2 (PGE2) synthesis and increases growth of prostate cancer cells. To further elucidate the mechanisms involved in AA-induced prostate cell growth, induction of c-fos expression by AA was investigated in a human prostate cancer cell line, PC-3. c-fos mRNA was induced shortly after addition of AA, along with a remarkable increase in PGE2 production. c-fos expression and PGE2 production induced by AA was blocked by a cyclo-oxygenase inhibitor, flurbiprofen, suggesting that PGE2 mediated c-fos induction. Protein kinase A (PKA) inhibitor H-89 abolished induction of c-fos expression by AA, and partially inhibited PGE2 production. Protein kinase C (PKC) inhibitor GF109203X had no significant effect on c-fos expression or PGE2 production. Expression of prostaglandin (EP) receptors, which mediate signal transduction from PGE2 to the cells, was examined by reverse transcription polymerase chain reaction in several human prostate cell lines. EP4 and EP2, which are coupled to the PKA signalling pathway, were expressed in all cells tested. Expression of EP1, which activates the PKC pathway, was not detected. The current study showed that induction of the immediate early gene c-fos by AA is mediated by PGE2, which activates the PKA pathway via the EP2/4 receptor in the PC-3 cells.
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Affiliation(s)
- Y Chen
- Laboratory of Cell Growth, University of California, San Francisco and Veterans Affairs Medical Center, 94121, USA
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48
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Prostaglandin E2 regulation of cyclooxygenase expression in keratinocytes is mediated via cyclic nucleotide-linked prostaglandin receptors. J Lipid Res 2000. [DOI: 10.1016/s0022-2275(20)32029-0] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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49
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Ho ML, Chang JK, Chuang LY, Hsu HK, Wang GJ. Effects of nonsteroidal anti-inflammatory drugs and prostaglandins on osteoblastic functions. Biochem Pharmacol 1999; 58:983-90. [PMID: 10509750 DOI: 10.1016/s0006-2952(99)00186-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
It has been reported that nonsteroidal anti-inflammatory drugs (NSAIDs) suppress bone repair and bone remodeling but only mildly inhibit bone mineralization at the earlier stage of the repair process. We proposed that the proliferation and/or the earlier stage of differentiation of osteoblasts may be affected by NSAIDs. This study was designed to investigate whether NSAIDs affect the proliferation and/or differentiation of osteoblasts and whether these effects are prostaglandin (PG) mediated. The effects of PGE1 and PGE2, indomethacin, and ketorolac on thymidine incorporation, cell count, intracellular alkaline phosphatase (ALP) activity, and Type I collagen content in osteoblast-enriched cultures derived from fetal calvaria were evaluated. The results showed that both PGs and NSAIDs inhibited DNA synthesis and cell mitosis in a time- and concentration-dependent manner. However, intracellular ALP activity and Type I collagen content were stimulated at an earlier stage of differentiation in osteoblasts. These results suggested that (i) the inhibitory effect of ketorolac on osteoblastic proliferation contributes to its suppressive effects on bone repair and remodeling in vivo; (ii) PGEs and NSAIDs may be involved in matrix maturation and biologic bone mineralization in the earlier stage of osteoblast differentiation; and (iii) the effects of ketorolac and indomethacin on cell proliferation and differentiation may not be through the inhibition of the synthesis of PGE1 or PGE2.
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Affiliation(s)
- M L Ho
- Department of Physiology, Kaohsiung Medical College, Taiwan, ROC.
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50
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Hansen WR, Keelan JA, Skinner SJ, Mitchell MD. Key enzymes of prostaglandin biosynthesis and metabolism. Coordinate regulation of expression by cytokines in gestational tissues: a review. Prostaglandins Other Lipid Mediat 1999; 57:243-57. [PMID: 10402218 DOI: 10.1016/s0090-6980(99)00008-8] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Preterm labor is frequently associated with ascending intrauterine infection, accompanied by leukocytes infiltration and enhanced local production of cytokines and other inflammatory mediators. The resulting amplification of the inflammatory response, and of prostanoid production in particular, is postulated to be a principal mechanism of infection-driven preterm labor. In this review the effects of pro- and anti-inflammatory cytokines are discussed with respect to the expression of enzymes involved in three key steps of prostanoid biosynthesis and metabolism: liberation of arachidonic acid (AA), conversion of AA to bioactive prostanoids, and prostanoid catabolism. We suggest that by exerting coordinate actions on all three key steps, through multiple molecular mechanisms, inflammatory cytokines acutely up-regulate prostanoid production in intrauterine tissues.
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Affiliation(s)
- W R Hansen
- Department of Pharmacology and Clinical Pharmacology, University of Auckland School of Medicine, New Zealand
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