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Structural basis for a non-phosphorus-containing cyclic peptide binding to Grb2-SH2 domain with high affinity
Peng Li1, Manchao Zhang, Megan L Peach
1Laboratory of Medicinal Chemistry, National Cancer Institute, National Institutes of Health, 376 Boyles Street, Frederick, MD 21702-1201, USA.
Biochemical and Biophysical Research Communications
|July 25, 2003
Summary
Researchers developed potent, non-phosphorus Grb2-SH2 antagonists by optimizing cyclic peptides. These peptide inhibitors show promise for anti-cancer therapies by blocking the Ras activation pathway and inhibiting cancer cell growth.
Area of Science:
- Biochemistry
- Molecular Biology
- Medicinal Chemistry
Background:
- Blocking the interaction between phosphotyrosine (pTyr)-containing receptors and the Grb2 SH2 domain is a key anti-proliferative strategy targeting the Ras pathway.
- High-affinity binding to the Grb2 SH2 domain typically requires a pTyr-X-Asn motif.
Purpose of the Study:
- To investigate the structural basis for non-phosphorus peptide binding to the Grb2 SH2 domain.
- To develop potent Grb2 SH2 domain antagonists based on a novel non-pTyr cyclic peptide template.
Main Methods:
- Phage-display techniques to discover initial peptide binders.
- Structure-activity relationship (SAR) studies and peptidomimetic optimization.
- Molecular modeling to guide backbone conformation constraints.
- In vitro binding assays and whole-cell assays.
Main Results:
- Discovery of a non-pTyr cyclic peptide (G1) with moderate binding affinity.
- Identification of unique functional requirements for acidic side chains in non-phosphorylated peptides binding to Grb2 SH2.
- Development of potent Grb2 SH2 antagonists with low nanomolar binding affinity, such as cyclic peptide 20 (IC50=0.026 µM).
- Demonstration of cell membrane penetration and inhibition of Grb2-p185(erbB2) association in cancer cells by peptide 20.
Conclusions:
- Novel non-phosphorus cyclic peptides can effectively inhibit the Grb2 SH2 domain.
- Optimized peptide antagonists demonstrate high potency and cell permeability for potential anti-cancer applications.
- These findings offer a new avenue for developing non-cytotoxic anti-proliferative agents targeting the Ras pathway.