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Receptor-specific somatostatin analogs: correlations with biological activity
1Department of Medicine, Tulane University Medical Center, New Orleans, LA 70112-2699, USA.
Metabolism: Clinical and Experimental
|August 1, 1996
Summary
New somatostatin analogs show promise for targeting specific human somatostatin receptors (sst2 and sst5). Researchers compared affinities of various analogs for rat and human receptors, identifying potent compounds for further study.
Area of Science:
- Endocrinology
- Pharmacology
- Molecular Biology
Background:
- Somatostatin (SRIF) analogs are being developed for therapeutic applications.
- Selectivity for specific somatostatin receptor subtypes is crucial for efficacy and safety.
- Understanding differences between rodent and human receptor binding is essential for drug development.
Purpose of the Study:
- To compare the binding affinities of various somatostatin analogs to rat somatostatin receptor 2 (rsst2) and human somatostatin receptor 2 (hsst2).
- To evaluate the affinities of selected analogs for human somatostatin receptor 5 (hsst5).
- To identify novel analogs with high affinity and selectivity for human somatostatin receptors.
Main Methods:
- Radioligand binding assays were performed using rat AR42J cells expressing rsst2 and cells transfected with hsst2 and hsst5.
- Affinity (Ki) was measured for several cyclic and linear somatostatin analogs, including octreotide, lanreotide, RC-160, DC-23-99, and BIM-23268D.
- Selectivity ratios (sst5/sst2) were calculated for promising analogs.
Main Results:
- Typical analogs like octreotide and lanreotide showed similar affinities for rsst2 but lower affinities for hsst2.
- The analog DC-23-99, highly specific for rsst5 in rats, had reduced affinity for hsst5, but a D-Tyr1 version exhibited subnanomolar affinity.
- A novel analog, BIM-23268D, demonstrated superior affinity for hsst5 compared to known analogs and SRIF, with the highest sst5/sst2 selectivity observed.
Conclusions:
- Differences in binding affinities exist between rodent and human somatostatin receptors.
- Novel analogs like BIM-23268D show significant potential for selective targeting of human sst5.
- Further investigation of these analogs is warranted for potential therapeutic applications in conditions involving somatostatin receptor modulation.
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