Synthetic Antibody Mimics Based on Cancer-Targeting Immunostimulatory Peptides

Area of Science:

• Immunology
• Biotechnology
• Cancer Research

Background:

• Cancer immunotherapy aims to harness the immune system to fight tumors.
• Natural Killer (NK) cells are crucial immune effectors with potent anti-tumor activity.
• Developing targeted therapies that activate NK cells is a key challenge in cancer treatment.

Purpose of the Study:

• To design and develop novel de novo cancer-targeting immunostimulatory peptides.
• To create synthetic antibody mimics capable of activating NK cells against GRP78-expressing tumors.
• To evaluate the efficacy of these peptides in vitro and in vivo cancer models.

Main Methods:

• Synthesis of bifunctional peptides as linear dimers and branching trimers.
• Incorporation of NKp30-binding, GRP78-targeting, and tumor-cell-binding domains.
• In vitro assays for cell binding, NK cell activation (cytokine secretion), and co-culture cytotoxicity.
• In vivo studies using tumor-bearing mice to assess anti-tumor efficacy.

Main Results:

• A lead trimeric peptide demonstrated specific binding to GRP78-positive cancer cells (HepG2, A549).
• The peptide induced NK cell binding and activation, evidenced by cytokine release (IFN-γ, TNF-α, IL-8).
• Co-culture experiments showed peptide-mediated cancer cell apoptosis and reduced tumor growth in mice.

Conclusions:

• A novel trimeric peptide effectively targets GRP78-expressing tumors and activates NK cell-mediated immunity.
• This peptide represents a proof-of-concept for developing synthetic ligands that mimic antibody functions in cancer immunotherapy.
• The findings support the potential of peptide-based immunostimulatory agents for cancer treatment.