Effects of the phytoestrogen coumestrol on RANK-ligand-induced differentiation of osteoclasts.
Phytoestrogens, which have structural similarity to 17beta-estradiol, have been reported to act as agonists/antagonists of estrogen in animals and humans. Estrogen is known to have an important role in maintaining bone mass, because the concentration of serum estrogen decreases after menopause and the estrogen deficiency causes bone loss. In this study, we investigated the effects of coumestrol and other phytoestrogens on osteoclast differentiation using estrogen receptor alpha-transfected RAW264.7 (RAW264.7-ERalpha) cells. When the cells were cultured with the receptor activator of nuclear factor kappa B-ligand (RANKL), both formation of tartrate-resistant acid phosphatase (TRAP) positive multinucleated cells and TRAP activity were increased compared with control cells that were cultured in the absence of RANKL. Coumestrol decreased RANKL-induced formation of TRAP-positive multinucleated cells and TRAP activity dose-dependently. RANKL-stimulated RAW264.7-ERalpha cells formed resorption pits on calcium phosphate films and the pit formation was inhibited by coumestrol in a dose-dependent manner. RT-PCR analyses revealed that coumestrol (10 microM) decreased mRNA levels of calcitonin receptor (CTR) and matrix metalloproteinase-9 (MMP9) in RANKL-treated cells. In addition, pretreatment of coumestrol decreased RANKL-induced phosphorylation of extracellular signal-regulated kinases/p44/42 (ERK1/2). These results suggest that coumestrol has an inhibitory effect on the differentiation of osteoclasts, at least partially via ERK1/2 pathway.
Kanno
Sanae
S
Environmental Health Sciences Division, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan. sanae@nies.go.jp
Hirano
Seishiro
S
Kayama
Fujio
F
D000135:Acid Phosphatase / Q000378:metabolism; D000818:Animals; D015415:Biomarkers; D015153:Blotting, Western; D001862:Bone Resorption / Q000473:pathology; D002352:Carrier Proteins / Q000494:pharmacology*; D056657:Cathepsin K; D002403:Cathepsins / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D003375:Coumestrol / Q000494:pharmacology*; D004958:Estradiol / Q000494:pharmacology; D047628:Estrogen Receptor alpha / Q000378:metabolism; D004968:Estrogens, Non-Steroidal / Q000494:pharmacology*; D015726:Giant Cells / Q000187:drug effects; D007527:Isoenzymes / Q000378:metabolism; D008264:Macrophages / Q000502:physiology; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000494:pharmacology*; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010010:Osteoclasts / Q000187:drug effects* / Q000648:ultrastructure; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000071681:Tartrate-Resistant Acid Phosphatase; D014162:Transfection
D015415:Biomarkers; D002352:Carrier Proteins; D047628:Estrogen Receptor alpha; D004968:Estrogens, Non-Steroidal; D007527:Isoenzymes; D008562:Membrane Glycoproteins; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; C505687:Tnfrsf11a protein, mouse; C505689:Tnfsf11 protein, mouse; D004958:Estradiol; D020928:Mitogen-Activated Protein Kinases; D000135:Acid Phosphatase; C000605511:Acp5 protein, mouse; D000071681:Tartrate-Resistant Acid Phosphatase; D002403:Cathepsins; C534130:CTSK protein, human; D056657:Cathepsin K; C534132:Ctsk protein, mouse; D020780:Matrix Metalloproteinase 9; D003375:Coumestrol