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Pegvisomant, a growth hormone-specific antagonist, undergoes cellular internalization
M Maamra1, J J Kopchick, C J Strasburger
1Sheffield University, Clinical Sciences, Northern General Hospital, Sheffield, United Kingdom.
The Journal of Clinical Endocrinology and Metabolism
|September 10, 2004
Summary
Pegvisomant, a growth hormone antagonist, is internalized by cells despite its size and long half-life. This internalization occurs without activating signaling, suggesting it aids in pegvisomant clearance.
Area of Science:
- Pharmacology
- Endocrinology
- Cell Biology
Background:
- Growth hormone receptor (GHR) activation by growth hormone (GH) leads to signaling and receptor internalization.
- Pegvisomant is a GH antagonist used for acromegaly, designed to block GHR dimerization and signaling.
- Pegvisomant features polyethylene glycol modifications for extended circulation time and reduced renal clearance.
Purpose of the Study:
- To investigate the cellular internalization of pegvisomant.
- To determine if GHR signaling is required for pegvisomant internalization.
- To identify potential mechanisms for pegvisomant clearance from circulation.
Main Methods:
- Studying pegvisomant uptake in cells expressing the GHR.
- Assessing intracellular trafficking of pegvisomant.
- Correlating internalization with GHR signaling pathways.
Main Results:
- Pegvisomant is internalized by cells expressing the GHR, irrespective of its large size and prolonged plasma half-life.
- Internalization of pegvisomant does not trigger intracellular signal transduction.
- These findings suggest that GHR signaling is not essential for the intracellular trafficking of pegvisomant.
Conclusions:
- GHR conformational changes necessary for signaling are not required for pegvisomant's intracellular transport.
- Cellular internalization represents a potential mechanism contributing to the clearance of pegvisomant.
- Understanding pegvisomant internalization provides insights into its pharmacokinetic profile and therapeutic efficacy.