Thienoquinolines as novel disruptors of the PKCε/RACK2 protein-protein interaction.
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.
Biocenter, Division of Medical Biochemistry, Innsbruck Medical University , Innrain 80-82, A-6020 Innsbruck, Austria.
Florian
F
Rechfeld
Peter
P
Gruber
Johannes
J
Kirchmair
Markus
M
Boehler
Nina
N
Hauser
Georg
G
Hechenberger
Dorota
D
Garczarczyk
Gennady B
GB
Lapa
Maria N
MN
Preobrazhenskaya
Peter
P
Goekjian
Thierry
T
Langer
Johann
J
Hofmann
D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D002642:Chick Embryo; D055808:Drug Discovery; D006367:HeLa Cells; D006801:Humans; D008958:Models, Molecular; D010766:Phosphorylation; D011485:Protein Binding; D051744:Protein Kinase C-epsilon / Q000037:antagonists & inhibitors* / Q000737:chemistry; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D021381:Protein Transport / Q000187:drug effects; D011804:Quinolines / Q000494:pharmacology*; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface / Q000037:antagonists & inhibitors* / Q000737:chemistry; D013329:Structure-Activity Relationship; D050807:ets-Domain Protein Elk-1 / Q000378:metabolism
D047428:Protein Kinase Inhibitors; D011804:Quinolines; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface; D050807:ets-Domain Protein Elk-1; D051744:Protein Kinase C-epsilon