A BAG-1-inhibitory peptide, GO-Pep, suppresses c-Raf activity in cancer

Area of Science:

• Biochemistry
• Molecular Biology
• Cancer Research

Background:

• The BCL2-associated athanogene 1 (BAG-1) protein interacts with various partners, notably c-Raf kinase, promoting cancer cell survival.
• Modulating these interactions presents a therapeutic target for cancer treatment.

Purpose of the Study:

• To elucidate the structural basis of BAG-1S and its interaction with c-Raf.
• To develop a peptide-based inhibitor targeting the BAG-1S:c-Raf interface for cancer therapy.

Main Methods:

• Hydrogen-deuterium exchange mass spectrometry (HDX-MS) to determine BAG-1S structure and identify druggable sites.
• LC-MS/MS-coupled cell-free binding assays to map the BAG-1S:c-Raf interaction interface.
• Site-directed mutagenesis to validate key interaction residues.
• Cell-penetrating peptide (CPP) conjugation for intracellular delivery.

Main Results:

• HDX-MS revealed the higher-order structure of BAG-1S, highlighting a potential druggable site on its BAG domain.
• A 20-amino acid region on BAG-1S was identified as the primary c-Raf interaction site, with K149 and L156 identified as critical residues.
• Mutating K149 and L156 attenuated cancer cell survival (MCF-7).
• A c-Raf-derived peptide, conjugated with a CPP, successfully penetrated cells and induced apoptosis in cancer cells.

Conclusions:

• The study successfully mapped the BAG-1S:c-Raf interaction interface and identified critical residues.
• A novel peptide inhibitor targeting this interface demonstrated potent anticancer activity by inducing apoptosis.
• This peptide represents a promising therapeutic strategy for BAG-1-overexpressed and/or MAPK-driven cancers.