Farnesol and Geranylgeraniol Prevent Activation of Caspases by Aminobisphosphonates: Biochemical Evidence for Two Distinct Pharmacological Classes of Bisphosphonate Drugs
- 1Bone Research Group, Department of Medicine and Therapeutics, University of Aberdeen Medical School, Foresterhill, Aberdeen, United Kingdom (H.L.B., J.C.F., M.J.R.); 2Department of Human Metabolism and Clinical Biochemistry, University of Sheffield Medical School, Sheffield, United Kingdom (J.C.F.); and Departments of 3Pharmaceutical Chemistry (S.A.) and 4Pharmaceutics (J.M.), University of Kuopio, Kuopio, Finland
Abstract
Recently, advances have been made in understanding the molecular mechanisms by which bisphosphonate drugs inhibit bone resorption. Studies with the macrophage-like cell line J774 have suggested that alendronate, an amino-containing bisphosphonate, causes apoptosis by preventing post-translational modification of GTP-binding proteins with isoprenoid lipids. However, clodronate, a nonaminobisphosphonate, does not inhibit protein isoprenylation but can be metabolized intracellularly to a cytotoxic, β-γ-methylene (AppCp-type) analog of ATP. These observations raise the possibility that bisphosphonates can be divided into two groups with distinct molecular mechanisms of action depending on the nature of the R2 side chain. We addressed this question by directly comparing the ability of three aminobisphosphonates (alendronate, ibandronate, and pamidronate) and three nonaminobisphosphonates (clodronate, etidronate, and tiludronate) to inhibit protein isoprenylation and activate caspase-3-like proteases or to be metabolized to AppCp-type nucleotides by J774 cells. All three aminobisphosphonates inhibited protein isoprenylation and activated caspase-3-like proteases. Apoptosis and caspase activation after 24-h treatment with the aminobisphosphonates could be prevented by addition of farnesol or geranylgeraniol, confirming that these bisphosphonates inhibit the metabolic mevalonate pathway. No AppCp-type metabolites of the aminobisphosphonates could be detected by mass spectrometry. The three nonaminobisphosphonates did not inhibit protein isoprenylation or cause activation of caspase-3-like proteases, but were incorporated into AppCp-type nucleotides. Taken together, these observations clearly demonstrate that bisphosphonate drugs can be divided into two pharmacological classes: the aminobisphosphonates, which act by inhibiting protein isoprenylation, and the less potent nonaminobisphosphonates, which act through the intracellular accumulation of AppCp-type metabolites.
Footnotes
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Send reprint requests to: Dr. M. J. Rogers, Dept. of Medicine & Therapeutics, University of Aberdeen Medical School, Polwarth Building, Foresterhill, Aberdeen AB25 2ZD, UK. E-mail:m.j.rogers{at}abdn.ac.uk
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H.L.B. is a recipient of the Ann Stansfield Fellowship from the National Association for the Relief of Paget’s Disease (NARPD). J.C.F. is supported by a studentship from the Medical Research Council. This work was also funded by the Technical Development Centre, Finland.
- Abbreviations:
- Ac-DEVD-AMC
- N-acetyl-Asp-Glu-Val-Asp-7-amino-4-methylcoumarin
- Ac-YVAD-AMC
- N-acetyl-Tyr-Val-Ala-Asp-7-amino-4-methylcoumarin
- FPLC
- fast performance liquid chromatography
- MS
- mass spectrometry
- FPP
- farnesyl pyrophosphate
- GGPP
- geranylgeranyl pyrophosphate
- CLO
- dichloromethylene-1,1-bisphosphonate
- ETI
- 1-hydroxyethylidene-1,1-bisphosphonate
- TIL
- chloro-4-phenylthiomethylene-1,1-bisphosphonate
- ALN
- 4-amino-1-hydroxybutylidene-1,1-bisphosphonate
- PAM
- 3-amino-1-hydroxypropylidene-1,1-bisphosphonate
- IBA
- 1-hydroxy-3(methylpentylamino)-propylidene-1,1-bisphosphonate
- FOH
- farnesol
- GGOH
- geranylgeraniol
- ACN
- acetonitrile
- ESI
- electrospray ionization
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- Received November 30, 1998.
- Accepted April 12, 1999.
- The American Society for Pharmacology and Experimental Therapeutics
