Trichostatin A-mediated upregulation of p21^WAF1 contributes to osteoclast apoptosis

Abstract

Histone deacetylase inhibitors (HDIs), a new class of anti-cancer agents, have been reported to suppress formation of osteoclast precursors and their fusion into multinucleated cells. However, little is known about the effect of HDIs on mature osteoclasts, which may have significance for their therapeutic use. Here, we demonstrate a novel action of HDIs on osteoclast apoptosis. Primary multinucleated mature osteoclasts were prepared from mouse bone marrow cells. Treatment of osteoclasts with the HDI trichostatin A (TSA) caused apoptosis, as confirmed by annexin V staining and caspase activation. TSA caused the upregulation of p21^WAF1 in osteoclasts. To understand the role of p21^WAF1 upregulation in TSA-treated osteoclasts, shRNA against p21^WAF1-containing lentivirus was introduced into osteoclasts. The suppression of p21^WAF1 decreased TSA-directed osteoclast apoptosis. Collectively, our results provide evidence that TSA causes osteoclast apoptosis, which involves, in part, TSA-induced upregulation of p21^WAF1, and strongly supports HDIs as potential therapeutic agents for excessive bone resorption.