Projects

Mimicking proline-rich motifs

A novel structure-guided approach in drug design to develop inhibitors for proline-rich mediated protein-protein interactions

Proline-rich sequences are amongst the most frequent motifs in eukaryotic cells and play a pivotal role in many signaling pathway. They mediate the assembly of molecular complexes by interacting with versatile recognition domains contained in various intracellular proteins. Signaling proline-rich motife recognizing domains (PRDs) include Src-homology 3 (SH3), WW, GYF, Profilin and Drosophila enabled (Ena)/vasodilator-stimulated phosphoprotein (VASP) homology 1 (EVH1) domains. Small-molecule competitors of yet so far undruggable PRDs are urgently needed for functional analysis of large-scale genomics and proteomics data.

We developed a modular strategy to obtain an extendable toolkit of chemical fragments (ProMs) designed to replace pairs of conserved prolines in recognition motifs. These rationally designed chemical fragments mimic dipeptide motifs (e.g. PP, xP, Px), adopting backbone angles typical of a left-handed polyproline II helix (PPII). Up to now more than 15 new chemical entities were synthezised using an innovative modular synthesis concept developed by  Prof. H.-G. Schmalz at the Universität zu Köln (Inst. Organische Synthese).  As a proof of concept we were able to develop, for the first time, low molecular weight inhibitors of Ena/VASP EVH1 domains. Our collaboration focused on the design of sp3-rich, non toxic scaffolds that are mimicking the challenging recognition of proline-rich motifs. We used an interdisciplinary approach in which scaffolds are in silico designed, new synthesis routes found, inhibitors cocrystallized and evaluated in biophysical and cell biological assays.

Ena/VASP - a druggable antimetastatic target

Metastasis is a hallmark of cancer and the leading cause of mortality among cancer patients. Strikingly, the last 10 years of cancer research increased the survival rate for patients with diagnosed metastatic disease by less than 3%. The lack of metastasis-directed drugs and the limited progress of metastasis-directed drug development efforts make new approaches essential in drug design.
Cells of the primary tumor undergo a developmental regulatory program which leads to a specific signature of gene expression, which results in a migration state of cancer cells. Pivotal in this process are the Ena/VASP proteins involved in the regulation of the actin cytoskeleton.

In contrast to current drug targets, Ena/VASP acts most downstream of cancer signaling cascades where bypassing these routes is unlikely. Since localization of Ena/VASP depends on the EVH1 domain, the domain displays a favourable drug target. However, small molecules interfering with EVH1 remain elusive.
We succeeded in designing a 706 Da compound that bound with a Kd of 4 μM and displaced natural binding partners in pull-down experiments from a native lysate of invasive breast cancer cell line. Immunofluorescence confirmed that Ena/VASP was delocalized from cellular membrane protrusions. Furthermore, the cell-membrane-permeable compound inhibited the invasion in a boyden chamber assay by two-thirds. Based on these encouraging results, the group of Prof. van Dijke (University Leiden) contacted us. In cooperation we tested the inhibitor in an in vivo zebra fish study that verified the antimetastatic effect.
Our approach yielded in patented inhibitors that are unique and the only small molecules known to address Ena/VASP at the time.

Leibniz-Forschungsinstitut für Molekulare Pharmakologie im Forschungsverbund Berlin e.V. (FMP)
Campus Berlin-Buch
Robert-Roessle-Str. 10
13125 Berlin, Germany
+4930 94793 - 100 
+4930 94793 - 109 (Fax)
info(at)fmp-berlin.de

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