5'-Triphosphate-siRNA: turning gene silencing and Rig-I activation against melanoma

Nat Med. 2008 Nov;14(11):1256-63. doi: 10.1038/nm.1887. Epub 2008 Nov 2.

Abstract

Genetic and epigenetic plasticity allows tumors to evade single-targeted treatments. Here we direct Bcl2-specific short interfering RNA (siRNA) with 5'-triphosphate ends (3p-siRNA) against melanoma. Recognition of 5'-triphosphate by the cytosolic antiviral helicase retinoic acid-induced protein I (Rig-I, encoded by Ddx58) activated innate immune cells such as dendritic cells and directly induced expression of interferons (IFNs) and apoptosis in tumor cells. These Rig-I-mediated activities synergized with siRNA-mediated Bcl2 silencing to provoke massive apoptosis of tumor cells in lung metastases in vivo. The therapeutic activity required natural killer cells and IFN, as well as silencing of Bcl2, as evidenced by rescue with a mutated Bcl2 target, by site-specific cleavage of Bcl2 messenger RNA in lung metastases and downregulation of Bcl-2 protein in tumor cells in vivo. Together, 3p-siRNA represents a single molecule-based approach in which Rig-I activation on both the immune- and tumor cell level corrects immune ignorance and in which gene silencing corrects key molecular events that govern tumor cell survival.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antineoplastic Agents / therapeutic use
  • Apoptosis / immunology
  • Cell Line, Tumor
  • Cell Transplantation
  • DEAD Box Protein 58
  • DEAD-box RNA Helicases / genetics
  • DEAD-box RNA Helicases / metabolism*
  • Disease Models, Animal
  • Enzyme Activation
  • Female
  • Gene Expression Regulation, Neoplastic
  • Gene Silencing*
  • Humans
  • Immunity, Innate / immunology
  • Melanoma / genetics*
  • Melanoma / immunology
  • Melanoma / metabolism*
  • Melanoma / pathology
  • Mice
  • Phosphates / metabolism*
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins c-bcl-2
  • RNA, Small Interfering / genetics*
  • RNA, Small Interfering / metabolism
  • RNA, Small Interfering / therapeutic use

Substances

  • Antineoplastic Agents
  • Phosphates
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-bcl-2
  • RNA, Small Interfering
  • Bcl2 protein, mouse
  • DDX58 protein, human
  • Ddx58 protein, mouse
  • DEAD Box Protein 58
  • DEAD-box RNA Helicases