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Systematic development of bombesin/gastrin-releasing peptide antagonists
D H Coy1, R T Jensen, N Y Jiang
1Department of Medicine, Tulane University Medical Center, New Orleans, La.
Journal of the National Cancer Institute. Monographs
|January 1, 1992
Summary
Researchers developed novel bombesin (Bn) receptor antagonist analogues with varied agonist/antagonist properties. These potent, shorter-chain antagonists show promise for specific therapeutic applications by fine-tuning receptor interactions.
Area of Science:
- Pharmacology
- Medicinal Chemistry
- Molecular Biology
Background:
- Bombesin (Bn) receptor antagonists are crucial for understanding receptor signaling.
- Previous analogues exhibited variable agonist/antagonist profiles across different systems.
- Species and assay-dependent activity complicates drug development.
Purpose of the Study:
- To develop more potent and selective bombesin receptor antagonists.
- To investigate structure-activity relationships for improved antagonist properties.
- To identify pure antagonists with consistent efficacy across various models.
Main Methods:
- Synthesis of novel [psi CH2NH(13-14)]Bn(6-14) and desMet14Bn(6-13)NH2 analogues.
- In vitro evaluation of receptor binding affinity and functional activity in Swiss 3T3 cells, guinea pig, and rat pancreatic acini.
- Systematic modification of peptide structures to eliminate partial agonism and enhance antagonist potency.
Main Results:
- Developed potent antagonists with affinities as low as 4 nM (Ki).
- Identified specific structural modifications (e.g., C-terminal substitutions, alkyl esters) to eliminate partial agonist activity.
- [D-Phe6]Bn(6-13)OMe demonstrated pure antagonist activity and high affinity across all tested systems.
- New antagonists showed minimal affinity for neuromedin B-preferring bombesin receptors.
Conclusions:
- Novel bombesin receptor antagonists with tunable properties have been successfully developed.
- Structural modifications are key to achieving pure antagonist profiles and high potency.
- These refined antagonists offer improved selectivity and potential for therapeutic applications.