Reference : Zoledronic acid up-regulates bone sialoprotein expression in osteoblastic cells throu...
Scientific journals : Article
Human health sciences : Oncology
Life sciences : Biochemistry, biophysics & molecular biology
Zoledronic acid up-regulates bone sialoprotein expression in osteoblastic cells through Rho GTPase inhibition
Chaplet, Michaël [Université de Liège - ULg > > > > > >]
Deroanne, Christophe mailto [Université de Liège - ULg > Département des sciences biomédicales et précliniques > Protéines et glycoprot. de matr.extracell. et membran.basal. >]
Fisher, Larry W. [> > > >]
Castronovo, Vincenzo mailto [Université de Liège - ULg > Département des sciences biomédicales et précliniques > Biologie générale et cellulaire >]
Bellahcene, Akeila mailto [Université de Liège - ULg > Département des sciences biomédicales et précliniques > Labo de recherche sur les métastases >]
Detry, Cédric mailto [Université de Liège - ULg > Services généraux (Faculté de médecine) > Service administratif de la Faculté (Médecine) >]
Biochemical Journal
Portland Press
Pt 3
Yes (verified by ORBi)
[en] bisphosphonate ; bone sialoprotein ; osteoblast-like cells ; post-transcriptional regulation ; Rho GTPase ; zoledronic acid
[en] Clinical practice reveals that osteoporotic women treated with BPs (bisphosphonates) show an increased bone mass density and a reduced risk of fractures. However, the mechanisms leading to these beneficial effects of BPs are still poorly understood. We hypothesized that ZOL (zoledronic acid), a potent third-generation BP, may induce the expression of proteins associated with the bone-forming potential of osteoblastic cells such as BSP (bone sialoprotein). Expression of BSP gene is up-regulated by hormones that promote bone formation and has been associated with de novo bone mineralization. Using real-time reverse transcriptase-PCR and Western-blot analysis, we demonstrated that ZOL increased BSP expression in Saos-2 osteoblast-like cells. Nuclear run-on and mRNA decay assays showed no effect at the transcriptional level but a stabilization of BSP transcripts in ZOL-treated cells. ZOL effect on BSP expression occurred through an interference with the mevalonate pathway since it was reversed by either mevalonate pathway intermediates or a Rho GTPase activator. We showed that ZOL impaired membrane localization of RhoA in Saos-2 cells indicating reduced prenylation of this protein. By the use of small interfering RNAs directed to RhoA and Rac1, we identified both Rho GTPases as negative regulators of BSP expression in Saos-2 cells. Our study demonstrates that ZOL induces BSP expression in osteoblast-like cells through inactivation of Rho GTPases and provides a potential mechanism to explain the favourable effects of ZOL treatment on bone mass and integrity.
Fonds de la Recherche Scientifique (Communauté française de Belgique) - F.R.S.-FNRS ; TELEVIE ; University Attraction Pole (IPAP5/31) ; European Commission (METABRE - STROMA)

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