Conjugates of HA2 with octaarginine-grafted HPMA copolymer offer effective siRNA delivery and gene silencing in cancer cells

Moran Golan, Valeria Feinshtein, Ayelet David

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


The key for successful gene silencing is to design a safe and efficient siRNA delivery system for the transfer of therapeutic nucleic acids into the target cells. Here, we describe the design of hydrophilic N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer displaying multiple copies of octaarginine (R8) and its use in promoting the effective delivery of small interfering RNA (siRNA) molecules intracellularly. Fluorescein-5-isothiocyanate (FITC)-labeled HPMA copolymer-bound R8 (P-R8-FITC) was synthesized with increasing R8 molar ratios (4–9.5 mol-%) to define the optimal R8 content that allowed the polymer to serve both as a siRNA-binding domain and as an intracellular transduction moiety mediating improved cellular delivery. A subunit of the influenza virus hemagglutinin (HA2), known for its ability to disrupt endosomal membranes, was further conjugated to P-R8-FITC copolymer to promote endosomal escape. Of the different P-(R8)-FITC conjugates considered, only that polymer containing the highest mol-% of R8 (P-(R8)9.5-FITC) was able to encapsulate siRNA molecules into nano-sized polyion complexes (PICs) presenting positive surface charge, low in vitro cytotoxicity, and high serum stability. P-(R8)9.5-FITC/cy5-siRNA complexes can efficiently deliver siRNA molecules into cells, while naked siRNA or siRNA encapsulated within polymers with lower R8 mol-% were unable to transfect the same cells. Conjugation of HA2 fusogenic peptide to P-(R8)-FITC significantly decreased the oncogenic RAC1 mRNA levels in cancer cells. This indicates that P-(R8)-(HA2)-FITC can deliver siRNA into target cells, and that the siRNA can reach the perinuclear region where it interacts with the RNA-induced silencing complex.

Original languageEnglish
Pages (from-to)103-112
Number of pages10
JournalEuropean Journal of Pharmaceutics and Biopharmaceutics
StatePublished - 1 Dec 2016


  • Cancer therapy
  • Cell penetrating peptides
  • Endosomal escape motif
  • HPMA copolymer
  • Octaarginine
  • siRNA delivery

ASJC Scopus subject areas

  • Biotechnology
  • Pharmaceutical Science


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