Synthetic Studies on Centromere-Associated Protein-E (CENP-E) Inhibitors: 2. Application of Electrostatic Potential Map (EPM) and Structure-Based Modeling to Imidazo[1,2-a]pyridine Derivatives as Anti-Tumor Agents

J Med Chem. 2015 Oct 22;58(20):8036-53. doi: 10.1021/acs.jmedchem.5b00836. Epub 2015 Oct 1.

Abstract

To develop centromere-associated protein-E (CENP-E) inhibitors for use as anticancer therapeutics, we designed novel imidazo[1,2-a]pyridines, utilizing previously discovered 5-bromo derivative 1a. By site-directed mutagenesis analysis, we confirmed the ligand binding site. A docking model revealed the structurally important molecular features for effective interaction with CENP-E and could explain the superiority of the inhibitor (S)-isomer in CENP-E inhibition vs the (R)-isomer based on the ligand conformation in the L5 loop region. Additionally, electrostatic potential map (EPM) analysis was employed as a ligand-based approach to optimize functional groups on the imidazo[1,2-a]pyridine scaffold. These efforts led to the identification of the 5-methoxy imidazo[1,2-a]pyridine derivative (+)-(S)-12, which showed potent CENP-E inhibition (IC50: 3.6 nM), cellular phosphorylated histone H3 (p-HH3) elevation (EC50: 180 nM), and growth inhibition (GI50: 130 nM) in HeLa cells. Furthermore, (+)-(S)-12 demonstrated antitumor activity (T/C: 40%, at 75 mg/kg) in a human colorectal cancer Colo205 xenograft model in mice.

MeSH terms

  • Animals
  • Antineoplastic Agents / chemical synthesis*
  • Antineoplastic Agents / pharmacology*
  • Binding Sites
  • Chromosomal Proteins, Non-Histone / antagonists & inhibitors*
  • Drug Design
  • HeLa Cells
  • Histones / metabolism
  • Humans
  • Ligands
  • Mice
  • Mitosis / drug effects
  • Models, Molecular
  • Mutagenesis, Site-Directed
  • Phosphorylation
  • Pyridines / chemical synthesis*
  • Pyridines / pharmacology*
  • Static Electricity
  • Structure-Activity Relationship
  • Xenograft Model Antitumor Assays

Substances

  • Antineoplastic Agents
  • Chromosomal Proteins, Non-Histone
  • Histones
  • Ligands
  • Pyridines
  • centromere protein E
  • imidazo(1,2-a)pyridine