A fusogenic dengue virus-derived peptide enhances antitumor efficacy of an antibody-ribonuclease fusion protein targeting the EGF receptor

Protein Eng Des Sel. 2014 Oct;27(10):331-7. doi: 10.1093/protein/gzu040.


Due to its frequent overexpression in a variety of solid tumors the epidermal growth factor receptor (EGFR) is a well-established target for therapeutic interventions in epithelial cancers. In order to target EGFR in head and neck cancer, we have generated a ribonuclease (RNase) fusion protein comprising a humanized anti-EGFR antibody single-chain Fv fragment (scFv) and Ranpirnase, an RNase from Rana pipiens. Fusion of Ranpirnase to the N-terminus of the scFv via a flexible glycine-serine linker (G4S)3 resulted in very poor cytotoxicity of the fusion protein. As endosomal accumulation and lysosomal degradation have been reported to diminish the antitumor efficacy of ribonuclease or toxin-based immunoagents, we explored a fusion peptide from dengue virus that has been reported to be involved in the endosomal escape of the virus. This peptide was introduced as a linker between Ranpirnase and the scFv moiety. The modified immunoRNase exhibited exceptionally high cytotoxicity toward EGFR-expressing head and neck cell lines without affecting specificity. These results indicate that endosomal entrapment needs to be considered for Ranpirnase-based immunoagents and might be overcome by the use of tailored transduction domains from viral proteins.

Keywords: EGFR; Ranpirnase; dengue virus; endosomal escape; immunoRNase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / chemistry
  • Antineoplastic Agents / metabolism*
  • Antineoplastic Agents / pharmacology
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • Dengue Virus / genetics*
  • ErbB Receptors / chemistry
  • ErbB Receptors / metabolism*
  • Humans
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism*
  • Recombinant Fusion Proteins / pharmacology
  • Ribonucleases / chemistry
  • Ribonucleases / genetics
  • Ribonucleases / metabolism*
  • Single-Chain Antibodies / chemistry
  • Single-Chain Antibodies / genetics
  • Single-Chain Antibodies / metabolism*


  • Antineoplastic Agents
  • Recombinant Fusion Proteins
  • Single-Chain Antibodies
  • ErbB Receptors
  • Ribonucleases
  • ranpirnase