Coupling to polymeric scaffolds stabilizes biofunctional peptides for intracellular applications

Area of Science:

• Bioconjugation Chemistry
• Cellular Biology
• Drug Delivery Systems

Background:

• Apoptosis-inducing peptides are crucial for cancer therapy but suffer from short intracellular half-lives.
• Enhancing peptide stability and delivery is key to improving their therapeutic efficacy.
• N-hydroxypropyl methacrylamide (HPMA) copolymers are established drug delivery vehicles.

Purpose of the Study:

• To investigate the effect of HPMA copolymer conjugation on the activity of apoptosis-inducing peptides.
• To elucidate the molecular mechanisms behind the enhanced peptide activity.
• To assess the stability and intracellular residence time of peptide-polymer conjugates.

Main Methods:

• Synthesis of BH3-domain peptides conjugated to HPMA copolymer via native chemical ligation.
• Introduction of peptides and conjugates into cells using electroporation and nona-arginine conjugation.
• Confocal microscopy for assessing loading efficiency and intracellular residence.
• Fluorescence correlation spectroscopy for determining proteolytic degradation in cell lysates.

Main Results:

• HPMA conjugation via one-pot synthesis yielded active peptide-polymer conjugates.
• Conjugates showed increased intracellular residence time compared to free peptides.
• Proteolytic degradation was significantly reduced in both cell lysates and intracellularly.
• HPMA conjugation markedly increased the half-life of the peptides.

Conclusions:

• HPMA copolymer conjugation is an effective strategy to enhance the cellular activity of apoptosis-inducing peptides.
• Proteolytic protection is the primary mechanism responsible for the improved peptide efficacy.
• This approach offers a promising avenue for developing more stable and potent peptide-based therapeutics.