title: In vitro studies with the calcimimetic, cinacalcet HCl, on normal human adult osteoblastic and osteoclastic cells.
abstract: This study examined whether the calcium-sensing receptor (CaR) is expressed in normal adult human osteoblastic and osteoclastic cells in culture, and whether the calcimimetic, cinacalcet HCl (AMG 073), potentiates the effects of calcium (via CaR, or some other receptor/mechanism). When mouse or human osteoblastic cells were treated with higher concentrations of calcium (6.6 or 8.6 mM in alpha-MEM/10% FBS) than present in control cultures (1.6 mM), the previously well-documented increase in cell number was demonstrated. Cinacalcet HCl affected cell proliferation of CHO cells transfected with CaR, dose dependently, but had no effect on human or mouse osteoblastic cell proliferation in calcium-containing medium (1.6 or 8.6 mM). To test cinacalcet HCl and calcium on osteoclastic cells, peripheral blood mononuclear cells were cultured in medium containing RANK ligand and M-CSF, supplemented with calcium, and/or cinacalcet HCl. Tartrate-resistant acid phosphatase-positive multinucleated osteoclastic cells on plastic or bone were then counted at 11 and 21 days, respectively. Calcium (greater than 6.0 mM) inhibited osteoclast formation, but cinacalcet HCl (30-1000 nM) had no effect on osteoclastic formation or resorption in the presence of calcium (1.6 or 6.1 mM). RT-PCR did not detect CaR in human, rat, or mouse primary osteoblastic cells and cell lines or osteoclastic cells. In conclusion, these studies indicate that the calcium-induced increase in osteoblastic cell number, and the decrease in formation/function of osteoclastic cells, involves a mechanism or receptor other than CaR. In addition, the calcimimetic agent did not potentiate the effects of calcium on normal adult human bone cells in vitro.
authors.affiliation: Department of Metabolic Disorders, Amgen, Inc., Thousand Oaks, CA 91320, USA. shalhoub@amgen.com
authors.forename: Victoria
authors.initials: V
authors.lastname: Shalhoub
authors.forename: Mario
authors.initials: M
authors.lastname: Grisanti
authors.forename: Jen
authors.initials: J
authors.lastname: Padagas
authors.forename: Sheila
authors.initials: S
authors.lastname: Scully
authors.forename: Alana
authors.initials: A
authors.lastname: Rattan
authors.forename: Meiying
authors.initials: M
authors.lastname: Qi
authors.forename: Brian
authors.initials: B
authors.lastname: Varnum
authors.forename: Chris
authors.initials: C
authors.lastname: Vezina
authors.forename: David
authors.initials: D
authors.lastname: Lacey
authors.forename: David
authors.initials: D
authors.lastname: Martin
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000187:drug effects; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism*; D002455:Cell Division; D002460:Cell Line; D002478:Cells, Cultured; D000069449:Cinacalcet; D006224:Cricetinae; D003470:Culture Media / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007150:Immunohistochemistry; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D016173:Macrophage Colony-Stimulating Factor / Q000378:metabolism; D051379:Mice; D009281:Naphthalenes / Q000494:pharmacology*; D010006:Osteoblasts / Q000187:drug effects*; D010010:Osteoclasts / Q000187:drug effects*; D012333:RNA, Messenger / Q000378:metabolism; D044169:Receptors, Calcium-Sensing / Q000096:biosynthesis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014018:Tissue Distribution; D014162:Transfection
chemical_list: D003470:Culture Media; D009281:Naphthalenes; D012333:RNA, Messenger; D044169:Receptors, Calcium-Sensing; D016173:Macrophage Colony-Stimulating Factor; D002118:Calcium; D000069449:Cinacalcet