Redox-Responsive Disulfide Cyclic Peptides: A New Strategy for siRNA Delivery

Area of Science:

• Biotechnology
• Molecular Biology
• Drug Delivery Systems

Background:

• RNA interference (RNAi) offers a promising therapeutic strategy but faces delivery challenges.
• Efficient and safe delivery of small interfering RNA (siRNA) is critical for RNAi therapeutics.
• Existing delivery methods often struggle with stability and cellular uptake.

Purpose of the Study:

• To design and synthesize novel peptide-based carriers for enhanced siRNA delivery.
• To investigate the potential of disulfide-constraining peptides for intracellular siRNA release.
• To evaluate the efficacy and safety of these new peptide/siRNA complexes for cancer therapy.

Main Methods:

• Synthesis of disulfide-constraining cyclic and hybrid peptides using tryptophan and arginine.
• Assessment of cellular internalization of siRNA using flow cytometry and confocal microscopy.
• Evaluation of siRNA protection against nucleases via gel electrophoresis.
• Cytotoxicity assessment using cell viability and LC50 calculations.
• Protein silencing efficacy determined by Western blot analysis of STAT3 expression.

Main Results:

• Novel peptides C4 and H4 demonstrated effective cellular internalization of siRNA (∼70%).
• Peptides successfully protected siRNA from nuclease degradation.
• Minimal cytotoxicity was observed in tested cell lines.
• Significant protein silencing (70-75% reduction in STAT3) was achieved in human triple-negative breast cancer cells.

Conclusions:

• A new family of peptide-based siRNA delivery systems has been developed.
• These peptides facilitate safe and efficient siRNA delivery, overcoming nuclease degradation.
• The developed system shows promise for RNAi-based therapeutic applications, particularly in cancer treatment.