ABSTRACT
Following the discovery of (R)-roscovitine's beneficial effects in three polycystic kidney disease (PKD) mouse models, cyclin-dependent kinases (CDKs) inhibitors have been investigated as potential treatments. We have used various affinity chromatography approaches to identify the molecular targets of roscovitine and its more potent analog (S)-CR8 in human and murine polycystic kidneys. These methods revealed casein kinases 1 (CK1) as additional targets of the two drugs. CK1ε expression at the mRNA and protein levels is enhanced in polycystic kidneys of 11 different PKD mouse models as well as in human polycystic kidneys. A shift in the pattern of CK1α isoforms is observed in all PKD mouse models. Furthermore, the catalytic activities of both CK1ε and CK1α are increased in mouse polycystic kidneys. Inhibition of CK1ε and CK1α may thus contribute to the long-lasting attenuating effects of roscovitine and (S)-CR8 on cyst development. CDKs and CK1s may constitute a dual therapeutic target to develop kinase inhibitory PKD drug candidates.
Subject(s)
Casein Kinase 1 epsilon/antagonists & inhibitors , Casein Kinase Ialpha/antagonists & inhibitors , Kidney/drug effects , Polycystic Kidney Diseases/prevention & control , Protein Kinase Inhibitors/pharmacology , Purines/pharmacology , Pyridines/pharmacology , Roscovitine/pharmacology , Animals , Casein Kinase 1 epsilon/genetics , Casein Kinase 1 epsilon/metabolism , Casein Kinase Ialpha/genetics , Casein Kinase Ialpha/metabolism , Catalysis , Chromatography, Affinity/methods , Disease Models, Animal , Humans , Kidney/enzymology , Kidney/pathology , Mice, Transgenic , Polycystic Kidney Diseases/enzymology , Polycystic Kidney Diseases/genetics , Polycystic Kidney Diseases/pathology , Protein Binding , Protein Kinase Inhibitors/metabolism , Purines/metabolism , Pyridines/metabolism , Roscovitine/metabolism , Signal Transduction/drug effectsABSTRACT
Tubulin is a validated target for antitumor drugs. However, the effectiveness of these microtubule-interacting agents is limited by the fact that they are substrates for drug efflux pumps (P-glycoprotein) and/or by the acquisition of point mutations in tubulin residues important for drug-tubulin binding. To bypass these resistance systems, we have identified and characterized a novel synthetic imidazole derivative IRC-083927, which inhibits the tubulin polymerization by a binding to the colchicine site. IRC-083927 inhibits in vitro cell growth of human cancer cell lines in the low nanomolar range. More interesting, it remains highly active against cell lines resistant to microtubule-interacting agents (taxanes, Vinca alkaloids, or epothilones). Such resistances are due to the presence of efflux pumps (NCI-H69/LX4 resistant to navelbine and paclitaxel) and/or the presence of mutations on beta-tubulin and on alpha-tubulin and beta-tubulin (A549.EpoB40/A549.EpoB480 resistant to epothilone B or paclitaxel). IRC-083927 displayed cell cycle arrest in G(2)-M phase in tumor cells, including in the drug-resistant cells. In addition, IRC-083927 inhibited endothelial cell proliferation in vitro and vessel formation in the low nanomolar range supporting an antiangiogenic behavior. Finally, chronic oral treatment with IRC-083927 (5 mg/kg) inhibits the growth of two human tumor xenografts in nude mice (C33-A, human cervical cancer and MDA-MB-231, human hormone-independent breast cancer). Together, the antitumor effects induced by IRC-083927 on tumor models resistant to tubulin agents support further investigations to fully evaluate its potential for the treatment of advanced cancers, particularly those resistant to current clinically available drugs.
