SCF^βTrCP-mediated degradation of SHARP1 in triple-negative breast cancer

Area of Science:

• Oncology
• Molecular Biology
• Cancer Metastasis

Background:

• Triple-negative breast cancer (TNBC) is aggressive, with high metastasis and recurrence rates.
• The transcription factor SHARP1 suppresses TNBC metastasis by inhibiting hypoxia-inducible factors.
• Loss of SHARP1 correlates with poor patient survival in breast cancer.

Purpose of the Study:

• To investigate the regulatory mechanisms controlling SHARP1 stability in TNBC.
• To explore the potential of targeting SHARP1 degradation as a therapeutic strategy for TNBC.

Main Methods:

• Investigated SHARP1 protein stability and degradation pathways.
• Identified the E3 ubiquitin ligase SCF^βTrCP as a key regulator of SHARP1.
• Utilized phosphodegron mapping (Ser240, Glu245) to understand SHARP1 ubiquitylation and degradation.
• Employed a non-degradable SHARP1 mutant (S240A/E245A) in preclinical mouse models of TNBC.

Main Results:

• SHARP1 is an unstable protein targeted for proteasomal degradation by SCF^βTrCP.
• SHARP1 degradation is mediated by a phosphodegron (Ser240, Glu245), crucial for ubiquitylation.
• Mice with TNBC cells expressing non-degradable SHARP1 showed reduced tumor growth and increased tumor-free survival.

Conclusions:

• SHARP1 stability is tightly regulated by βTrCP-mediated proteasomal degradation.
• Inhibiting βTrCP-dependent SHARP1 degradation may represent a novel therapeutic approach for TNBC.
• Stabilizing SHARP1 could be a promising strategy to combat TNBC metastasis and improve patient outcomes.