Stabilizing the eIF4G1 α-helix increases its binding affinity with eIF4E: implications for peptidomimetic design...

Area of Science:

• Biochemistry
• Molecular Biology
• Cancer Therapeutics

Background:

• Eukaryotic initiation factor 4E (eIF4E) overexpression is common in various cancers, promoting tumor growth by enhancing translation of oncogenic proteins.
• Targeting eIF4E presents a potential therapeutic strategy for human cancers.
• Existing eIF4E inhibitors lack sufficient potency or biological activity.

Purpose of the Study:

• To design and synthesize a novel, helically stabilized peptide targeting eIF4E.
• To evaluate the binding affinity, potency, and biological activity of the stabilized peptide.
• To assess the therapeutic potential of cell-penetrating peptide-fused derivatives in cancer models.

Main Methods:

• Peptide synthesis based on the eIF4G1 binding motif with stabilized α-helix.
• Circular dichroism (CD) measurements to confirm α-helix stabilization.
• Binding affinity (K(d)) determination, cell-based cap-dependent translational reporter assays, WST-1 assays for cell metabolism, propidium iodide and Annexin V staining for cell death analysis.

Main Results:

• The helically stabilized peptide exhibited significantly higher binding potency (K(d) of 9.43±2.57 nM) compared to the template peptide.
• The stabilized peptide demonstrated significant biological activity in cell-based assays at 400 μM, unlike the template peptide.
• TAT-fused stabilized peptides effectively inhibited cap-dependent translation, induced significant cell death via apoptosis, and reduced G1/G2 cell populations.

Conclusions:

• Helically stabilized peptidomimetics targeting eIF4E are potent inhibitors of cap-dependent translation.
• TAT-fusion enhances cellular uptake and efficacy, leading to apoptosis in cancer cells.
• These findings provide a strong foundation for developing novel peptidomimetic-based cancer therapeutics targeting eIF4E.