Molecular Basis for the N-Terminal Bromodomain-and-Extra-Terminal-Family Selectivity of a Dual Kinase-Bromodomain Inhibitor

J Med Chem. 2018 Oct 25;61(20):9316-9334. doi: 10.1021/acs.jmedchem.8b01248. Epub 2018 Oct 16.

Abstract

As regulators of transcription, epigenetic proteins that interpret post-translational modifications to N-terminal histone tails are essential for maintaining cellular homeostasis. When dysregulated, "reader" proteins become drivers of disease. In the case of bromodomains, which recognize N-ε-acetylated lysine, selective inhibition of individual bromodomain-and-extra-terminal (BET)-family bromodomains has proven challenging. We describe the >55-fold N-terminal-BET bromodomain selectivity of 1,4,5-trisubstituted-imidazole dual kinase-bromodomain inhibitors. Selectivity for the BRD4 N-terminal bromodomain (BRD4(1)) over its second bromodomain (BRD4(2)) arises from the displacement of ordered waters and the conformational flexibility of lysine-141 in BRD4(1). Cellular efficacy was demonstrated via reduction of c-Myc expression, inhibition of NF-κB signaling, and suppression of IL-8 production through potential synergistic inhibition of BRD4(1) and p38α. These dual inhibitors provide a new scaffold for domain-selective inhibition of BRD4, the aberrant function of which plays a key role in cancer and inflammatory signaling.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • A549 Cells
  • Humans
  • Imidazoles / chemistry*
  • Imidazoles / pharmacology*
  • Protein Domains
  • Protein Kinase Inhibitors / chemistry*
  • Protein Kinase Inhibitors / pharmacology*
  • Water / chemistry
  • p38 Mitogen-Activated Protein Kinases / antagonists & inhibitors
  • p38 Mitogen-Activated Protein Kinases / chemistry

Substances

  • Imidazoles
  • Protein Kinase Inhibitors
  • Water
  • imidazole
  • p38 Mitogen-Activated Protein Kinases