Suberoylanilide Hydroxamic Acid (SAHA; Vorinostat) Causes Bone Loss by Inhibiting Immature Osteoblasts

Bone. 2011 May 1;48(5):1117-26. doi: 10.1016/j.bone.2011.01.007. Epub 2011 Jan 19.


Histone deacetylase (Hdac) inhibitors are used clinically to treat cancer and epilepsy. Although Hdac inhibition accelerates osteoblast maturation and suppresses osteoclast maturation in vitro, the effects of Hdac inhibitors on the skeleton are not understood. The purpose of this study was to determine how the pan-Hdac inhibitor, suberoylanilide hydroxamic acid (SAHA; a.k.a. vorinostat or Zolinza(TM)) affects bone mass and remodeling in vivo. Male C57BL/6J mice received daily SAHA (100mg/kg) or vehicle injections for 3 to 4weeks. SAHA decreased trabecular bone volume fraction and trabecular number in the distal femur. Cortical bone at the femoral midshaft was not affected. SAHA reduced serum levels of P1NP, a bone formation marker, and also suppressed tibial mRNA levels of type I collagen, osteocalcin and osteopontin, but did not alter Runx2 or osterix transcripts. SAHA decreased histological measures of osteoblast number but interestingly increased indices of osteoblast activity including mineral apposition rate and bone formation rate. Neither serum (TRAcP 5b) nor histological markers of bone resorption were affected by SAHA. P1NP levels returned to baseline in animals which were allowed to recover for 4weeks after 4weeks of daily SAHA injections, but bone density remained low. In vitro, SAHA suppressed osteogenic colony formation, decreased osteoblastic gene expression, induced cell cycle arrest, and caused DNA damage in bone marrow-derived adherent cells. Collectively, these data demonstrate that bone loss following treatment with SAHA is primarily due to a reduction in osteoblast number. Moreover, these decreases in osteoblast number can be attributed to the deleterious effects of SAHA on immature osteoblasts, even while mature osteoblasts are resistant to the harmful effects and demonstrate increased activity in vivo, indicating that the response of osteoblasts to SAHA is dependent upon their differentiation state. These studies suggest that clinical use of SAHA and other Hdac inhibitors to treat cancer, epilepsy or other conditions may potentially compromise skeletal structure and function.

MeSH terms

  • Acetylation / drug effects
  • Animals
  • Biomarkers / blood
  • Body Weight / drug effects
  • Bone Marrow Cells / drug effects
  • Bone Marrow Cells / metabolism
  • Bone Marrow Cells / pathology
  • Bone Remodeling / drug effects
  • Bone Resorption / blood
  • Bone Resorption / chemically induced*
  • Cell Count
  • Cell Cycle / drug effects
  • Cell Differentiation / drug effects*
  • Colony-Forming Units Assay
  • DNA Damage
  • Femur / drug effects
  • Femur / metabolism
  • Femur / pathology
  • Gene Expression Regulation / drug effects
  • Histones / metabolism
  • Hydroxamic Acids / adverse effects*
  • Hydroxamic Acids / pharmacology*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Osteoblasts / drug effects*
  • Osteoblasts / metabolism
  • Osteoblasts / pathology*
  • Osteogenesis / drug effects
  • Peptide Fragments / metabolism
  • Procollagen / metabolism
  • Time Factors
  • Vorinostat


  • Biomarkers
  • Histones
  • Hydroxamic Acids
  • Peptide Fragments
  • Procollagen
  • procollagen Type I N-terminal peptide
  • Vorinostat