Identification of a potent and selective chemical probe for exploring the role of Mediator complex-associated protein kinases CDK8 and CDK19 in human disease [LS-174-T]

ABSTRACT: There is an unmet need for chemical tools to explore the role of the Mediator complex in human pathologies ranging from cancer to cardiovascular disease. Here we determine that CCT251545 a WNT-pathway inhibitor discovered by cell-based screening is a potent and selective chemical probe for the Mediator complex-associated protein kinases CDK8 and CDK19. CCT251545 is an ATP competitive inhibitor with >100-fold selectivity over 291 other kinases. X-ray crystallography demonstrates Type 1 binding involving insertion of the CDK8 C-terminus into the ligand binding site. In contrast to Type II inhibitors of CDK8/19 CCT251545 displays potent cell-based activity. We show that CCT251545 and close analogues not only alter WNT-pathway regulated gene expression but also other CDK8/19 targets including STAT1-regulated gene expression. Consistent with this we find that phospho-STAT1SER727 is a biomarker of CDK8 kinase activity in vitro and in vivo. Finally we demonstrate in vivo activity of CCT251545 in WNT-dependent tumours. LS-174-T colon cancer cells were treated with 715 nM of Compound 6 (IC90 of TCF dependent luciferase) for 0, 4 or 24h. Three samples with three biological repeats each. Sample were hybridized against human reference. Compound 6 is a close analogue of a 3,4,5-trisubstituted pyridine series identified from a high-throughput cell-based reporter assay of WNT signalling. It was shown to be potent and selective inhibitor of the Mediator complex-associated protein kinases CDK8 and CDK19. Its is ATP competitive inhibitor with >100-fold selectivity over 291 other kinases. X-ray crystallography demonstrates Type 1 binding involving insertion of the CDK8 C-terminus into the ligand-binding site.

ORGANISM(S): Homo sapiens

SUBMITTER: Robert Poele 

PROVIDER: E-GEOD-67846 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress