Zoledronic acid treatment impairs protein geranyl-geranylation for biological effects in prostatic cells

BACKGROUND: Nitrogen-containing bisphosphonates (N-BPs) have been designed to inhibit osteoclast-mediated bone resorption. However, it is now accepted that part of their anti-tumor activities is related to interference with the mevalonate pathway. METHODS: We investigated the effects of zoledronic acid (ZOL), on cell proliferation and protein isoprenylation in two tumoral (LnCAP, PC-3,), and one normal established (PNT1-A) prostatic cell line. To assess if inhibition of geranyl-geranylation by ZOL impairs the biological activity of RhoA GTPase, we studied the LPA-induced formation of stress fibers. The inhibitory effect of ZOL on geranyl geranyl transferase I was checked biochemically. Activity of ZOL on cholesterol biosynthesis was determined by measuring the incorporation of (14)C mevalonate in cholesterol. RESULTS: ZOL induced dose-dependent inhibition of proliferation of all the three cell lines although it appeared more efficient on the untransformed PNT1A. Whatever the cell line, 20 μM ZOL-induced inhibition was reversed by geranyl-geraniol (GGOH) but neither by farnesol nor mevalonate. After 48 hours treatment of cells with 20 μM ZOL, geranyl-geranylation of Rap1A was abolished whereas farnesylation of HDJ-2 was unaffected. Inhibition of Rap1A geranyl-geranylation by ZOL was rescued by GGOH and not by FOH. Indeed, as observed with treatment by a geranyl-geranyl transferase inhibitor, treatment of PNT1-A cells with 20 μM ZOL prevented the LPA-induced formation of stress fibers. We checked that in vitro ZOL did not inhibit geranyl-geranyl-transferase I. ZOL strongly inhibited cholesterol biosynthesis up to 24 hours but at 48 hours 90% of this biosynthesis was rescued. CONCLUSION: Although zoledronic acid is currently the most efficient bisphosphonate in metastatic prostate cancer management, its mechanism of action in prostatic cells remains unclear. We suggest in this work that although in first intention ZOL inhibits FPPsynthase its main biological actitivity is directed against protein Geranylgeranylation

Consequences for clinical biochemists of the modifications of the creatinine-based evaluation of glomerular filtration rate between 2005 and 2008.

Les recommandations internationales de 2005 concernant l’insuffisance rénale chronique proposent une classification basée sur le débit de filtration glomérulaire (DFG). Depuis cette date, la question posée de la validité des formules évaluant le DFG, et des créatininémies qui y sont insérées, se pose de façon encore plus cruciale qu’il y a quelques années. Pour les biologistes, les conséquences de ces recommandations cliniques sont importantes. En premier lieu, la formule classique de Cockcroft-Gault doit être abandonnée au profit de l’équation dite MDRD à 4 variables, et ce malgré les recommandations officielles françaises actuelles, qui devraient être modifiées d’ici peu. D’autre part, afin d’optimiser l’évaluation du DFG par cette formule, les biologistes doivent choisir entre la version dite « 186 » de l’équation MDRD, adaptée aux méthodes de dosage de la créatininémie non raccordées à la méthode de référence (chromatographie liquide ou gazeuse couplée à la spectrométrie de masse) et la version dite « 175 », adaptée aux méthodes de dosages raccordées. A ce jour, seules certaines méthodes enzymatiques ont fait la preuve de leur raccordement à une méthode de référence. L’avenir des méthodes colorimétriques classiques est incertain

Zoledronic acid treatment impairs protein geranyl-geranylation for biological effects in prostatic cells-3

<p><b>Copyright information:</b></p><p>Taken from "Zoledronic acid treatment impairs protein geranyl-geranylation for biological effects in prostatic cells"</p><p>BMC Cancer 2006;6():60-60.</p><p>Published online 15 Mar 2006</p><p>PMCID:PMC1434759.</p><p>Copyright © 2006 Goffinet et al; licensee BioMed Central Ltd.</p> (0.5 μM, 8–10 Ci/mmol) incorporation into a mutant form of H-ras with a geranyl-geranylation CAXX box. The level of prenylation is expressed as a percentage of maximum incorporation of [H]-prenyl, as determined by allowing the uninhibited reaction to go to completion. : Western-blot analysis; PC-3 cells are treated by vehicle, ZOL 20 μM; ZOL 20 μM + FOH 10 μM; ZOL 20 μM + GGOH 10 μM

Zoledronic acid treatment impairs protein geranyl-geranylation for biological effects in prostatic cells-0

<p><b>Copyright information:</b></p><p>Taken from "Zoledronic acid treatment impairs protein geranyl-geranylation for biological effects in prostatic cells"</p><p>BMC Cancer 2006;6():60-60.</p><p>Published online 15 Mar 2006</p><p>PMCID:PMC1434759.</p><p>Copyright © 2006 Goffinet et al; licensee BioMed Central Ltd.</p>nd D3, cells were treated by vehicle or increasing doses of zoledronate (ZOL: 5, 10, 15, 20 μM). At D5, the cells were fixed with TCA and stained with 0.4% sulforhodamine. Staining intensity was quantified at 540 nm. Results are expressed as the ratio OD/ODof three independent assays each performed six times. Error bars indicate inter-assay mean ± 1 SD. * indicates a significant difference versus non-treated cells (p < 0.01). PC3 PNT1A LNCa