1. Pharmacological inhibitors to identify roles of cathepsin K in cell-based studies: a comparison of available tools.
- Author
-
Desmarais S, Massé F, and Percival MD
- Subjects
- Animals, Benzamides pharmacology, Biphenyl Compounds pharmacology, Cathepsin K, Cell Line, Cell Line, Tumor, Epoxy Compounds pharmacology, Humans, Hydrazines pharmacology, Mice, Molecular Structure, Piperazines pharmacology, Rabbits, Rats, Cathepsins antagonists & inhibitors, Fibroblasts drug effects, Protease Inhibitors pharmacology
- Abstract
Cathepsin K (Cat K) degrades bone type I collagen and is a target for the pharmacological treatment of osteoporosis. Further roles for Cat K have been recently described, some of which are supported by the use of purportedly selective Cat K inhibitors in human and rodent cell-based assays. Twelve commercial and non-commercial Cat K inhibitors were profiled against a panel of purified human, rat, and mouse cysteine cathepsins and in two cell-based enzyme occupancy assays for activity against Cat K, B, and L. Ten inhibitors, including the carbohydrazide Cat K inhibitor II (Boc-Phe-Leu-NHNH-CO-NHNH-Leu-Z), the non-covalent K4b, and the epoxide NC-2300, have either little Cat K selectivity, or appear poorly cell penetrant. The amino-acetonitrile-containing inhibitors L-873724 and odanacatib show greater than 100-fold human Cat K enzyme selectivity and have similar IC(50) values against each cathepsin in cell-based and enzyme assays. The basic inhibitor balicatib has greater cellular potencies than expected on the basis of purified enzyme assays. The accumulation of [(14)C]-balicatib in fibroblasts is blocked by prior treatment of the cells with NH(4)Cl, consistent with balicatib having lysosomotropic properties. These results support the use of L-873724 and odanacatib as tools to identify novel roles for Cat K using human cell-based systems, but suggest using caution in the interpretation of studies employing the other compounds.
- Published
- 2009
- Full Text
- View/download PDF