Thienoquinolines as novel disruptors of the PKCε/RACK2 protein-protein interaction

J Med Chem. 2014 Apr 24;57(8):3235-46. doi: 10.1021/jm401605c. Epub 2014 Apr 8.

Abstract

Ten protein kinase C (PKC) isozymes play divergent roles in signal transduction. Because of sequence similarities, it is particularly difficult to generate isozyme-selective small molecule inhibitors. In order to identify such a selective binder, we derived a pharmacophore model from the peptide EAVSLKPT, a fragment of PKCε that inhibits the interaction of PKCε and receptor for activated C-kinase 2 (RACK2). A database of 330 000 molecules was screened in silico, leading to the discovery of a series of thienoquinolines that disrupt the interaction of PKCε with RACK2 in vitro. The most active molecule, N-(3-acetylphenyl)-9-amino-2,3-dihydro-1,4-dioxino[2,3-g]thieno[2,3-b]quinoline-8-carboxamide (8), inhibited this interaction with a measured IC50 of 5.9 μM and the phosphorylation of downstream target Elk-1 in HeLa cells with an IC50 of 11.2 μM. Compound 8 interfered with MARCKS phosphorylation and TPA-induced translocation of PKCε (but not that of PKCδ) from the cytosol to the membrane. The compound reduced the migration of HeLa cells into a gap, reduced invasion through a reconstituted basement membrane matrix, and inhibited angiogenesis in a chicken egg assay.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Proliferation / drug effects
  • Chick Embryo
  • Drug Discovery
  • HeLa Cells
  • Humans
  • Models, Molecular
  • Phosphorylation
  • Protein Binding
  • Protein Kinase C-epsilon / antagonists & inhibitors*
  • Protein Kinase C-epsilon / chemistry
  • Protein Kinase Inhibitors / pharmacology
  • Protein Transport / drug effects
  • Quinolines / pharmacology*
  • Receptors for Activated C Kinase
  • Receptors, Cell Surface / antagonists & inhibitors*
  • Receptors, Cell Surface / chemistry
  • Structure-Activity Relationship
  • ets-Domain Protein Elk-1 / metabolism

Substances

  • Protein Kinase Inhibitors
  • Quinolines
  • Receptors for Activated C Kinase
  • Receptors, Cell Surface
  • ets-Domain Protein Elk-1
  • Protein Kinase C-epsilon