A novel tankyrase inhibitor, MSC2504877, enhances the effects of clinical CDK4/6 inhibitors.

Inhibition of the PARP superfamily tankyrase enzymes suppresses Wnt/β-catenin signalling in tumour cells. Here, we describe here a novel, drug-like small molecule inhibitor of tankyrase MSC2504877 that inhibits the growth of APC mutant colorectal tumour cells. Parallel siRNA and drug sensitivity screens showed that the clinical CDK4/6 inhibitor palbociclib, causes enhanced sensitivity to MSC2504877. This tankyrase inhibitor-CDK4/6 inhibitor combinatorial effect is not limited to palbociclib and MSC2504877 and is elicited with other CDK4/6 inhibitors and toolbox tankyrase inhibitors. The addition of MSC2504877 to palbociclib enhances G 1 cell cycle arrest and cellular senescence in tumour cells. MSC2504877 exposure suppresses the upregulation of Cyclin D2 and Cyclin E2 caused by palbociclib and enhances the suppression of phospho-Rb, providing a mechanistic explanation for these effects. The combination of MSC2504877 and palbociclib was also effective in suppressing the cellular hyperproliferative phenotype seen in Apc defective intestinal stem cells in vivo. However, the presence of an oncogenic Kras p.G12D mutation in mice reversed the effects of the MSC2504877/palbociclib combination, suggesting one molecular route that could lead to drug resistance

Thieno[2,3-b)pyridinones as Antagonists on the Glycine Site of the N-methyl-ᴅ-aspartate Receptor - Binding Studies, Molecular Modeling and structure-Activity-Relationships

Within the frame of the synthesis of glycine antagonists, a series of novel thieno[2,3- b]pyridinones with substituted phenyl residues in position 5 were synthesised to investigate the importance of the torsion angle between the pyridinone skeleton and the phenyl ring for binding affinity. The parent compound, 4-hydroxy-5-phenylthieno[2,3-b]pyridine-6(7H)-one, and its thienyl analogue, exhibited highest potencies, whereas compounds with ortho-substituted aryl moieties in position 5 showed decreased activities. This seems to be due to unfavourable steric interactions and increased torsion angles between the thieno[2,3- b]pyridinone system and the aryl substituent in position 5. Further evidence is drawn by QSAR studies, which showed an inverse relationship between the size of the ortho-substituent and the binding affinity

Protein conformational flexibility modulates kinetics and thermodynamics of drug binding

An understanding of the dynamics of drug binding and unbinding processes is important for drug discovery. Here, the authors give insights into the binding mechanism of small drug-like molecules to human Hsp90 by combining thermodynamics and kinetics studies as well as molecular dynamics simulations