ABSTRACT
A series of inhibitors of Autotaxin (ATX) have been developed from a high throughput screening hit, 1a, which shows an alternative binding mode to known catalytic site inhibitors. Selectivity over the hERG channel and microsomal clearance were dependent on the lipophilicity of the compounds, and this was optimised by reduction of clogD whilst maintaining high affinity ATX inhibition. Compound 15a shows good oral exposure, and concentration dependent inhibition of formation of LPA in vivo, as shown in pharmacokinetic-pharmacodynamic (PK/PD) experiments.
Subject(s)
Amides/pharmacology , Cinnamates/pharmacology , Drug Development , Enzyme Inhibitors/pharmacology , Phosphoric Diester Hydrolases/metabolism , Tetrazoles/pharmacology , Amides/chemical synthesis , Amides/chemistry , Animals , Cinnamates/chemical synthesis , Cinnamates/chemistry , Dose-Response Relationship, Drug , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/chemistry , Humans , Mice , Models, Molecular , Molecular Structure , Rats , Structure-Activity Relationship , Tetrazoles/chemical synthesis , Tetrazoles/chemistryABSTRACT
A series of inhibitors of Autotaxin (ATX) has been developed using the binding mode of known inhibitor, PF-8380, as a template. Replacement of the benzoxazolone with a triazole zinc-binding motif reduced crystallinity and improved solubility relative to PF-8380. Modification of the linker region removed hERG activity and led to compound 12 - a selective, high affinity, orally-bioavailable inhibitor of ATX. Compound 12 concentration-dependently inhibits autotaxin and formation of LPA in vivo, as shown in pharmacokinetic-pharmacodynamic experiments.
Subject(s)
Drug Design , Phosphodiesterase Inhibitors/pharmacology , Phosphoric Diester Hydrolases/metabolism , Triazoles/pharmacology , Administration, Oral , Animals , Benzoxazoles/pharmacology , Drug Stability , Humans , Male , Microsomes/metabolism , Phosphodiesterase Inhibitors/administration & dosage , Phosphodiesterase Inhibitors/chemical synthesis , Phosphodiesterase Inhibitors/pharmacokinetics , Piperazines/pharmacology , Rats, Sprague-Dawley , Solubility , Triazoles/administration & dosage , Triazoles/chemical synthesis , Triazoles/pharmacokineticsABSTRACT
Using a parallel synthesis approach to target a non-conserved region of the PI3K catalytic domain a pan-PI3K inhibitor 1 was elaborated to provide alpha, delta and gamma isoform selective Class I PI3K inhibitors 21, 24, 26 and 27. The compounds had good cellular activity and were selective against protein kinases and other members of the PI3K superfamily including mTOR and DNA-PK.
Subject(s)
Phosphoinositide-3 Kinase Inhibitors , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/pharmacology , Thiazoles/chemistry , Thiazoles/pharmacology , Animals , Catalytic Domain , Female , Humans , Mice , Models, Molecular , Phosphatidylinositol 3-Kinases/chemistry , Phosphatidylinositol 3-Kinases/metabolism , Protein Isoforms/antagonists & inhibitors , Protein Isoforms/chemistry , Protein Isoforms/metabolism , Protein Kinase Inhibitors/pharmacokinetics , Rats , Signal Transduction/drug effects , Thiazoles/pharmacokineticsABSTRACT
Tyrosyl DNA phosphodiesterase 2 (TDP2) facilitates the repair of topoisomerase II (TOP2)-linked DNA double-strand breaks and, as a consequence, is required for cellular resistance to TOP2 "poisons". Recently, a deazaflavin series of compounds were identified as potent inhibitors of TDP2, in vitro. Here, however, we show that while some deazaflavins can induce cellular sensitivity to the TOP2 poison etoposide, they do so independently of TDP2 status. Consistent with this, both the cellular level of etoposide-induced TOP2 cleavage complexes and the intracellular concentration of etoposide was increased by incubation with deazaflavin, suggesting an impact of these compounds on etoposide uptake/efflux. In addition, deazaflavin failed to increase the level of TOP2 cleavage complexes or sensitivity induced by m-AMSA, which is a different class of TOP2 poison to which TDP2-defective cells are also sensitive. In conclusion, while deazaflavins are potent inhibitors of TDP2 in vitro, their limited cell permeability and likely interference with etoposide influx/efflux limits their utility in cells.
Subject(s)
Aza Compounds/chemistry , DNA-Binding Proteins/antagonists & inhibitors , Etoposide/pharmacokinetics , Flavins/pharmacology , Topoisomerase II Inhibitors/pharmacokinetics , Animals , Biological Transport , Cell Line , Chickens , Flavins/chemistry , Flavins/pharmacokinetics , Humans , Phosphoric Diester Hydrolases , Small Molecule Libraries/pharmacologyABSTRACT
MASTL (microtubule-associated serine/threonine kinase-like), more commonly known as Greatwall (GWL), has been proposed as a novel cancer therapy target. GWL plays a crucial role in mitotic progression, via its known substrates ENSA/ARPP19, which when phosphorylated inactivate PP2A/B55 phosphatase. When over-expressed in breast cancer, GWL induces oncogenic properties such as transformation and invasiveness. Conversely, down-regulation of GWL selectively sensitises tumour cells to chemotherapy. Here we describe the first structure of the GWL minimal kinase domain and development of a small-molecule inhibitor GKI-1 (Greatwall Kinase Inhibitor-1). In vitro, GKI-1 inhibits full-length human GWL, and shows cellular efficacy. Treatment of HeLa cells with GKI-1 reduces ENSA/ARPP19 phosphorylation levels, such that they are comparable to those obtained by siRNA depletion of GWL; resulting in a decrease in mitotic events, mitotic arrest/cell death and cytokinesis failure. Furthermore, GKI-1 will be a useful starting point for the development of more potent and selective GWL inhibitors.