Effect of pioglitazone on receptor activator of nuclear factor-kappa B expression in osteoclast from RAW264.7 cells

Abstract

To study the effect of pioglitazone, a synthetic peroxisome proliferator-activated receptor γ (PPARγ) agonist, on the RANKL-mediated osteoclastogenesis of osteoclast precursor cells, and to explore the function and mechanism of PPARγ in the osteoclast differentiation. Pioglitazone treatment of RAW264.7 murine macrophages were compared with those of simply cultured control and RANKL-mediated control. Accordingly, the RANKL-mediated cells were cultured with 30 ng/ml RANKL, then induced into significant multinuclear osteoclast formation. And pioglitazone treated cells were exposed to 10 µmol/L pioglitazone during the process of osteoclast differentiation under RANKL. The number of mature osteoclasts was calculated and the mRNA levels of RANK analyzed by real-time quantitative PCR. Pioglitazone significantly inhibited osteoclastogenesis of osteoclast precursor cells, the number of mature osteoclasts of pioglitazone treated group was (176 ± 58)/cm(2) and significantly less than the mature cells of RANKL induced group which number was (322 ± 74)/cm(2) (P < 0.01); and pioglitazone also significantly inhibited the mRNA expression of RANK, a typical differentiated factor of osteoclast, the number of the mRNA expression of RANK of pioglitazone treated group was 2.16 ± 0.74 and significantly less than the number of RANKL induced group (4.94 ± 0.39, P < 0.01). PPARγ agonist inhibited the differentiation of RAW264.7 towards osteoclast. It might be due to the suppression of RANK gene expression in the process of osteoclast differentiation.