Selective Covalent Targeting of Anti-apoptotic BFL-1 by a Sulfonium-Tethered Peptide

Area of Science:

• Biochemistry
• Molecular Biology
• Cancer Research

Background:

• Anti-apoptotic BCL-2 family proteins are key targets in cancer therapy.
• BFL-1, a BCL-2 family member, is overexpressed in chemoresistant cancers.
• A unique cysteine at BFL-1's binding interface presents a druggable target for irreversible inhibition.

Purpose of the Study:

• To develop a novel peptide inhibitor targeting the anti-apoptotic BFL-1 protein.
• To utilize a sulfonium-tethered peptide cyclization strategy for selective cysteine conjugation.
• To evaluate the efficacy of the BFL-1 inhibitor in vitro and in cancer cell lines.

Main Methods:

• Development of a sulfonium-tethered peptide cyclization strategy.
• Construction of a BFL-1 peptide inhibitor, B4-MC.
• In vitro and cellular assays to assess B4-MC's binding, uptake, localization, and anti-cancer activity.

Main Results:

• B4-MC selectively conjugates with BFL-1 both in vitro and in cell.
• The inhibitor demonstrated good cellular uptake and mitochondrial localization with BFL-1.
• B4-MC significantly inhibited the growth of BFL-1 over-expressed cancer cell lines.

Conclusions:

• A novel peptide inhibitor, B4-MC, was successfully developed using a unique cyclization strategy.
• B4-MC selectively targets and inhibits BFL-1, offering a potential therapeutic approach for chemoresistant cancers.
• The findings highlight the potential of targeting BFL-1 for cancer treatment by reactivating apoptosis.