Fluorinated aurein 1.2 analogues enhance antiproliferative activity against cancer cells and retain Gram-positive antibacterial effects
Background
The escalating crisis of antibiotic resistance and the persistent challenge of cancer necessitate novel therapeutic strategies. Antimicrobial peptides (AMPs) offer a promising scaffold due to their broad-spectrum activity and unique mechanisms. Aurein 1.2, a well-studied amphibian AMP, exhibits dual functionality against both bacterial and cancer cells. Its phenylalanine residues at positions 3 and 13 are crucial for membrane binding and biological activity, representing key targets for structural modification to optimize potency and selectivity.
Study Design
Researchers synthesized a series of novel aurein 1.2 analogues incorporating fluorinated phenylalanine via solid-phase peptide synthesis (SPPS) using Fmoc chemistry. Peptides were purified by High Performance Liquid Chromatography (HPLC) and characterized by mass spectrometry (MS). Antiproliferative activity was assessed in five human tumor cell lines (MCF-7, MDA-MB-231, U87, MG63) and one normal cell line (MCF-12F) using the MTT dye reduction assay after 72 h treatment. Antimicrobial activity was evaluated against both Gram-positive and Gram-negative bacteria, comparing results to positive controls.
Results
The synthesized aurein 1.2 analogues exhibited concentration-dependent antiproliferative effects against tumor cell lines. The analogue EH [Phe(4-F)]3,13[Lys]4 demonstrated the highest antiproliferative activity, achieving an IC50 = 9.79 ± 0.96 µM in U87 cells and an IC50 = 9.96 ± 0.8 µM in MG63 cells.
Significant selectivity, with an SI > 2, was observed for the peptide analogue EH [Phe(4-F)]3 in MCF-7 cells (SI = 2.08). All aurein 1.2 peptides and their analogues displayed better antibacterial activity against Gram-positive bacteria than Gram-negative strains. The best antimicrobial results were obtained with EH [Phe(4-F)]3,13[Lys]4, showing a MIC = 10 µg/ml against S. aureus 3703. However, the overall antibacterial activity of the analogues was weaker compared to the positive controls used in the study.
Key Findings
- Fluorinated aurein 1.2 analogues showed concentration-dependent antiproliferative effects against tumor cells.
- The analogue EH [Phe(4-F)]3,13[Lys]4 achieved IC50 = 9.79 ± 0.96 µM in U87 cells and IC50 = 9.96 ± 0.8 µM in MG63 cells.
- Peptide EH [Phe(4-F)]3 exhibited significant selectivity (SI = 2.08) in MCF-7 cells.
- Aurein 1.2 analogues possessed better antibacterial activity against Gram-positive bacteria.
- EH [Phe(4-F)]3,13[Lys]4 showed MIC = 10 µg/ml against S. aureus 3703.
Why It Matters
This study demonstrates that strategic fluorination of phenylalanine residues and lysine substitution can significantly enhance the antiproliferative potency and selectivity of aurein 1.2 analogues against cancer cells. This provides a valuable blueprint for designing multi-functional peptides with improved therapeutic profiles. While the antibacterial activity was modest compared to controls, the enhanced anti-cancer effects suggest a path toward developing novel agents for oncology, potentially as adjuvants or in combination therapies. Further optimization of these peptide scaffolds could lead to clinically translatable protocols for combating both drug-resistant infections and various cancers, leveraging the inherent bi-functionality of AMPs.
aurein 1.2
antimicrobial-peptides
cancer
antibiotic-resistance
peptide-synthesis
in-vitro