The Wnt pathway protein Dvl1 targets somatostatin receptor 2 for lysosome-dependent degradation

Area of Science:

• Endocrinology
• Molecular Biology
• Oncology

Background:

• Somatostatin receptor 2 (Sstr2) is a key target in neuroendocrine tumors.
• Sstr2 expression is variable and can decrease with treatment.
• Mechanisms regulating steady-state Sstr2 levels are not fully understood.

Purpose of the Study:

• To investigate novel mechanisms controlling Somatostatin receptor 2 (Sstr2) expression.
• To identify factors influencing Sstr2 levels independently of ligand binding.
• To explore therapeutic strategies for enhancing Sstr2 expression in neuroendocrine tumors.

Main Methods:

• Investigated Sstr2 interaction with Dishevelled 1 (Dvl1).
• Assessed the impact of Sstr2-Dvl1 interaction on receptor trafficking and signaling.
• Utilized Wnt pathway modulation (overexpression and inhibition) in neuroendocrine tumor cells.

Main Results:

• Sstr2 interacts with Dvl1 in a ligand-independent manner, promoting lysosomal degradation.
• This interaction does not affect Sstr2 internalization, recycling, or adenylyl cyclase signaling.
• Dvl1-dependent Sstr2 degradation is enhanced by Wnt overexpression and reduced by Wnt inhibitors.
• Wnt pathway inhibition increases Sstr2 expression in neuroendocrine tumor cells.

Conclusions:

• A novel mechanism for ligand-independent Sstr2 lysosomal degradation involving Dvl1 has been identified.
• The Wnt signaling pathway modulates Sstr2 expression.
• Targeting the Dvl1-Sstr2 interaction offers a potential strategy to enhance Sstr2 levels for improved targeted therapies in neuroendocrine tumors.