In Vitro Effects Of Pioglitazone On The Expression Of Components Of Wnt Signaling Pathway And Markers Of Bone Mineralization

Pioglitazone is an insulin-sensitizing thiazolidinedione (TZD) whose use is associated with bone loss. We examined the effects of pioglitazone on components of the Wnt signaling pathway (Wnt1, beta-catenin) and markers of bone mineralization [osteoprotegerin (OPG), bone sialoprotein (BSP), fibroblast growth factor (FGF) 23] as well as mineral content in human osteoblast hFOB 1.19 cells. hFOB 1.19 cells were cultured in K12/DMD medium with or without pioglitazone. PPAR gamma Wnt1, OPG, BSP, or FGF23 mRNA expression was measured using qRT-PCR; beta-catenin, OPG, BSP, or FGF23 using ELISA; and calcium or phosphate content using colorimetry. Treatment with pioglitazone resulted in increased expression of PPAR gamma mRNA in hFOB 1.19 osteoblasts. Pioglitazone decreased Wnt1 mRNA levels and suppressed components of Wnt signaling pathway as evidenced by a decrease in beta-catenin gene expression and secretion as well as beta-catenin specific activity. The expression and the activity of OPG, BSP, and FGF23 were also reduced by pioglitazone together with total (but not specific) calcium and phosphate content. Pioglitazone affects Wnt1 signaling pathway and mineral matrix regulation components in human osteoblasts.