Effects of antisense mediated inhibition of cathepsin K on human osteoclasts obtained from peripheral blood

Sofia Avnet, Annavera Lamolinara, Nicoletta Zini, Liliana Solimando, Gianni Quacquaruccio, Donatella Granchi, Nadir Mario Maraldi, Armando Giunti, Nicola Baldini

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Cathepsin K is a cystein protease that displays a proteolytic activity against Type I collagen and is abundantly and selectively expressed in osteoclasts where it plays a critical role in bone degradation. Its direct role in bone tissue has been defined by knock-out mice studies and inhibiting strategies in animals models. However, direct proof of cathepsin K function in human osteoclast model in vitro is lacking. The aim of this study is to analyze cathepsin K expression and localization in human osteoclasts obtained from peripheral blood and to examine cathepsin K function in these cells by antisense oligodeoxynucleotide (AS-ODN) strategy. AS-ODN was added to the culture of osteoclast precursors induced to differentiate by RANKL and M-CSF. AS-ODN treatment produced a significant down-regulation of cathepsin K mRNA (>80%) and protein expression, as verified respectively by Real-time PCR and by immunocytochemistry or Western blot. The cathepsin K inhibition caused an impairment of resorption activity as evaluated by a pit formation assay (p=0.045) and by electron microscopy, while the acidification process was unaffected. We demonstrated that antisense strategies against cathepsin K are selectively effective to inhibit resorption activity in human osteoclasts, like in animal models.

Original languageEnglish
Pages (from-to)1699-1708
Number of pages10
JournalJournal of Orthopaedic Research
Issue number8
Publication statusPublished - Aug 2006


  • Antisense
  • Bone resorption
  • Cathepsin K
  • In vitro
  • Osteoclasts

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine


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