title: Structure-activity relationships for inhibition of farnesyl diphosphate synthase in vitro and inhibition of bone resorption in vivo by nitrogen-containing bisphosphonates.
abstract: It has long been known that small changes to the structure of the R(2) side chain of nitrogen-containing bisphosphonates can dramatically affect their potency for inhibiting bone resorption in vitro and in vivo, although the reason for these differences in antiresorptive potency have not been explained at the level of a pharmacological target. Recently, several nitrogen-containing bisphosphonates were found to inhibit osteoclast-mediated bone resorption in vitro by inhibiting farnesyl diphosphate synthase, thereby preventing protein prenylation in osteoclasts. In this study, we examined the potency of a wider range of nitrogen-containing bisphosphonates, including the highly potent, heterocycle-containing zoledronic acid and minodronate (YM-529). We found a clear correlation between the ability to inhibit farnesyl diphosphate synthase in vitro, to inhibit protein prenylation in cell-free extracts and in purified osteoclasts in vitro, and to inhibit bone resorption in vivo. The activity of recombinant human farnesyl diphosphate synthase was inhibited at concentrations > or = 1 nM zoledronic acid or minodronate, the order of potency (zoledronic acid approximately equal to minodronate > risedronate > ibandronate > incadronate > alendronate > pamidronate) closely matching the order of antiresorptive potency. Furthermore, minor changes to the structure of the R(2) side chain of heterocycle-containing bisphosphonates, giving rise to less potent inhibitors of bone resorption in vivo, also caused a reduction in potency up to approximately 300-fold for inhibition of farnesyl diphosphate synthase in vitro. These data indicate that farnesyl diphosphate synthase is the major pharmacological target of these drugs in vivo, and that small changes to the structure of the R(2) side chain alter antiresorptive potency by affecting the ability to inhibit farnesyl diphosphate synthase.
authors.affiliation: Department of Medicine and Therapeutics, University of Aberdeen Medical School, Foresterhill, Aberdeen, United Kingdom.
authors.forename: J E
authors.initials: JE
authors.lastname: Dunford
authors.forename: K
authors.initials: K
authors.lastname: Thompson
authors.forename: F P
authors.initials: FP
authors.lastname: Coxon
authors.forename: S P
authors.initials: SP
authors.lastname: Luckman
authors.forename: F M
authors.initials: FM
authors.lastname: Hahn
authors.forename: C D
authors.initials: CD
authors.lastname: Poulter
authors.forename: F H
authors.initials: FH
authors.lastname: Ebetino
authors.forename: M J
authors.initials: MJ
authors.lastname: Rogers
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000818:Animals; D001862:Bone Resorption / Q000517:prevention & control*; D004164:Diphosphonates / Q000737:chemistry / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D051228:Geranyltranstransferase; D007202:Indicators and Reagents; D008798:Mevalonic Acid / Q000378:metabolism; D017672:Nitrogen Compounds / Q000737:chemistry / Q000494:pharmacology*; D010010:Osteoclasts / Q000378:metabolism; D011487:Protein Conformation; D017368:Protein Prenylation; D011817:Rabbits; D011994:Recombinant Proteins / Q000737:chemistry; D013329:Structure-Activity Relationship
chemical_list: D004164:Diphosphonates; D004791:Enzyme Inhibitors; D007202:Indicators and Reagents; D017672:Nitrogen Compounds; D011994:Recombinant Proteins; D019883:Alkyl and Aryl Transferases; D051228:Geranyltranstransferase; D008798:Mevalonic Acid