title: Curcumin diminishes human osteoclastogenesis by inhibition of the signalosome-associated I kappaB kinase.
abstract: OBJECTIVE
  Curcumin is a natural polyphenolic derogate extracted from spice turmeric, exhibiting anti-inflammatory and chemopreventive activities. It was described to interact with the signalosome-associated kinases and the proteasome-ubiquitin system, which both are involved in the osteoclastogenesis. Thus, we hypothesized that curcumin could diminish osteoclast differentiation and function.
  
  
  METHODS
  For the experiments considering osteoclast differentiation and resorptional activities, preosteoclasts were cultured for 4 weeks and treated with curcumin at subapoptotic dosages. Derived mature osteoclasts were identified as large, multinucleated cells with expression of tartrate-resistant acid phosphatase activity. Formation of resorption lacunae, a hallmark of osteoclast activity, was quantified using dentine pits and light microscopy. The signaling pathways were examined by ELISA-based methods and by immunoblotting.
  
  
  RESULTS
  Both 1 and 10 microM curcumin abrogated osteoclast differentiation (by 56 and 81%) and function (by 56 and 99%) (P < 0.05) dose-dependently. The effects were accompanied by the inhibition of I kappaB phosphorylation and NF-kappaB activation. In contrast, subtoxic doses did not have any significant effects on proteasome inhibition.
  
  
  CONCLUSIONS
  This manuscript is the first report that describes the effects of curcumin toward human osteoclastogenesis, and builds the framework for clinical trials of curcumin in the treatment of cancer-induced lytic bone disease.
authors.affiliation: Department of Hematology and Oncology, Charitéplatz 1, Charité, Universitätsmedizin Berlin, 10117, Berlin, Germany.
authors.forename: Ivana
authors.initials: I
authors.lastname: von Metzler
authors.forename: Holger
authors.initials: H
authors.lastname: Krebbel
authors.forename: Ulrike
authors.initials: U
authors.lastname: Kuckelkorn
authors.forename: Ulrike
authors.initials: U
authors.lastname: Heider
authors.forename: Christian
authors.initials: C
authors.lastname: Jakob
authors.forename: Martin
authors.initials: M
authors.lastname: Kaiser
authors.forename: Claudia
authors.initials: C
authors.lastname: Fleissner
authors.forename: Evangelos
authors.initials: E
authors.lastname: Terpos
authors.forename: Orhan
authors.initials: O
authors.lastname: Sezer