Downregulation of calcitonin receptor mRNA expression by calcitonin during human osteoclast-like cell differentiation

S. Takahashi, S. Goldring, M. Katz, S. Hilsenbeck, R. Williams, G. D. Roodman

Research output: Contribution to journalArticlepeer-review

108 Scopus citations

Abstract

Calcitonin inhibits both osteoclast formation and bone resorption, and is a primary treatment for patients with hypercalcemia and increased bone turnover. However, the clinical utility of calcitonin is limited because patients become refractory to calcitonin after several days (the calcitonin 'escape phenomenon'). The molecular basis for calcitonin 'escape' is unclear. To determine the regulatory mechanisms controlling calcitonin receptor (CTR) expression in osteoclasts and their precursors, we treated immature mononuclear precursors for human osteoclast-like multinucleated cells (MNC) formed in vitro with 1,25-(OH)2D3, to induce their differentiation to committed mononuclear precursors, and mature multinucleated osteoclasts, and used reverse transcriptase (RT)-PCR to assess expression of CTR mRNA in both committed mononuclear precursors and MNC. The PCR fragment produced was cloned and sequenced to confirm that it was derived from CTR mRNA. CTR mRNA expression was detected in mononuclear MNC precursors after 7 d of 1,25- (OH)2D3 treatment. It was also present in osteoclast-like MNC and highly purified giant cells from osteoclastomas, but not in monocytes or macrophage polykaryons formed in vitro. Calcitonin markedly decreased CTR but not actin mRNA expression in giant cells and MNC after 12 h, and removal of calcitonin restored CTR mRNA expression. Similarly, calcitonin decreased calcitonin- induced adenylate cyclase activity. These data suggest: (a) downregulation of CTR gene expression by calcitonin may in part explain the calcitonin 'escape phenomenon'; and (b) expression of CTR mRNA occurs in mononuclear osteoclast precursors within 7 d after exposure to 1,25-(OH)2D3.

Original languageEnglish (US)
Pages (from-to)167-171
Number of pages5
JournalJournal of Clinical Investigation
Volume95
Issue number1
DOIs
StatePublished - Jan 1995

Keywords

  • calcitonin escape
  • cell differentiation
  • gene expression
  • human marrow culture
  • polymerase chain reaction

ASJC Scopus subject areas

  • Medicine(all)

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