Enzyme-Triggered Charge and Conformation Switching for Tumor-Selective Peptide-Drug Conjugates.

Area of Science:

• Biochemistry
• Molecular Biology
• Oncology

Background:

• Anticancer drug functionalization with peptides enables tumor-selective delivery and reduced systemic toxicity.
• Gamma-glutamyltransferase (GGT) is overexpressed in certain tumors, making it a target for selective drug activation.

Purpose of the Study:

• To develop a GGT-responsive cell-penetrating peptide (P _-EE) for targeted activation of anticancer drugs in hepatocellular carcinoma.
• To create and evaluate a peptide-drug conjugate (CPT-P _-EE) for enhanced efficacy and reduced toxicity.

Main Methods:

• γ-glutamyl masking of penetratin to create the P _-EE peptide.
• Assessing peptide internalization and cytotoxicity in HepG2 (cancer) and NHDF (normal) cells.
• Conjugating camptothecin (CPT) to P _-EE to form CPT-P _-EE and evaluating its properties.
• Testing CPT-P _-EE efficacy and toxicity in vivo.

Main Results:

• P _-EE showed GGT-mediated cleavage, restoring charge and conformation for enhanced cell penetration.
• P _-EE exhibited 5-fold higher cytotoxicity in HepG2 cells compared to NHDF cells.
• CPT-P _-EE demonstrated improved aqueous solubility, potent antitumor activity, and over 50-fold reduced toxicity to normal cells.
• In vivo studies showed significant tumor suppression and prolonged survival with CPT-P _-EE without systemic toxicity.

Conclusions:

• The study established a generalizable enzyme-activatable peptide-drug conjugate platform.
• This platform integrates conformational switching with targeted delivery for precision chemotherapy.
• The approach shows promise for treating GGT-positive malignancies with reduced side effects.