Rational Design of a Bioconjugated Antitumor Peptide with Tumor-Selective Targeting and Microenvironment-Responsive Activation.

[OBJECTIVE] Bioactive peptides derived from natural or synthetic sources have shown significant potential for cancer therapy; however, their clinical application is often limited by poor tumor selectivity and systemic toxicity. In this work, we aim to develop a multifunctional antitumor peptide with enhanced tumor- targeting capability and therapeutic efficacy.

[METHODS] A cationic antimicrobial peptide (AMP, (KKWW) K-NH) was chemically modified via cysteine-mediated conjugation with 4-vinylphenylboronic acid, yielding the phenylboronic acid-conjugated AMP (PBA-AMP). Molecular dynamics (MD) simulations were performed to evaluate peptide-membrane interactions. Cellular uptake, cytotoxicity, and in vivo tumor-targeting and antitumor efficacy were assessed using MCF-7 cells and 4T1 tumor-bearing mice.

[RESULTS] MD simulations demonstrated that PBA-AMP exhibited rapid and stable binding to tumor cell membranes, maintaining consistent membrane interactions over a 50 ns simulation. Cellular studies revealed enhanced cellular uptake and increased cytotoxicity of PBA-AMP against MCF-7 breast cancer cell line (IC = 38.46 μM) compared to naive AMP (IC = 110 μM). In vivo imaging confirmed selective and prolonged tumor accumulation of PBA-AMP. Treatment with PBA-AMP significantly suppressed tumor growth in 4T1 tumor-bearing mice without observable systemic toxicity.

[CONCLUSIONS] This study presents a rational design strategy for engineering tumor-selective, microenvironment-responsive therapeutic peptides. PBA-AMP represents a promising candidate for targeted cancer therapy, offering improved efficacy and reduced off-target effects.