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.
Anand Divakaran  1 ,  Siva K Talluri  2 ,  Alex M Ayoub  2 ,  Neeraj K Mishra  2 ,  Huarui Cui  2 ,  John C Widen  1 ,  Norbert Berndt  3 ,  Jin-Yi Zhu  3 ,  Angela S Carlson  2 ,  Joseph J Topczewski  2 ,  Ernst K Schonbrunn  3 ,  Daniel A Harki  1 ,  William C K Pomerantz  1  2
Affiliations
  • 1. Department of Medicinal Chemistry , University of Minnesota , 2231 6th Street SE , Minneapolis , Minnesota 55455 , United States.
  • 2. Department of Chemistry , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States.
  • 3. Drug Discovery Department , H. Lee Moffitt Cancer Center and Research Institute , 12902 Magnolia Drive , Tampa , Florida 33612 , United States.
PMID: 30253095 DOI: 10.1021/acs.jmedchem.8b01248
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.

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