Nanovaccine loaded with poly I:C and STAT3 siRNA robustly elicits anti-tumor immune responses through modulating tumor-associated dendritic cells in vivo

Biomaterials. 2015 Jan:38:50-60. doi: 10.1016/j.biomaterials.2014.10.050. Epub 2014 Nov 12.


Although cancer vaccine-based immunotherapy holds great potential for cancer treatment, tumor-induced dendritic cell (DC) dysfunction remains to be the major obstacle for developing effective vaccines. Compared with normal DCs, tumor-associated DCs (TADCs) are less matured with poor responsiveness to Toll-like receptor (TLR) stimulation, which has been related with STAT3 hyperactivity. In the present study, Poly I:C (PIC, a TLR3 agonist), STAT3 siRNA and OVA antigen were co-encapsulated by poly (ethylene glycol)-b-poly (L-lysine)-b-poly (L-leucine) (PEG-PLL-PLLeu) polypeptide micelles to generate PMP/OVA/siRNA nanovaccine, which was aimed to effectively overcome DC dysfunction in vivo by deleting STAT3 gene in situ. The results showed that PMP/OVA/siRNA simultaneously facilitated the cellular uptake of OVA antigen and siRNA about 3-200 folds, and decreased STAT3 expression in TADCs over 50% both in vitro and in vivo. PMP/OVA/siRNA also elevated CD86 and CD40 expression as well as IL-12 production by TADCs more effectively than PMP/OVA did, indicating its strong potency of inducing TADC maturation and activation. Moreover, the immunization of PMP/OVA/siRNA rather than PMP/OVA effectively abrogated immunosuppression in the tumor microenvironment by increasing mature DCs and decreasing immunosuppressive cells in tumor-draining lymph nodes, which thereby led to potent anti-tumor immune responses and dramatic tumor regression with prolonged survival. Hence, in vivo co-delivery of immunopotentiator (PIC) and immunosuppressive gene silencer (STAT3 siRNA) by nanovaccines are expected to be a promising strategy to improve the therapeutic efficacy of cancer vaccines by modulating TADCs and overcoming tumor immunosupression.

Keywords: Nanovaccine; Polypeptide micelles; STAT3 siRNA; TLR3 agonist; Tumor immunosuppression; Tumor-associated dendritic cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cancer Vaccines / administration & dosage*
  • Cancer Vaccines / immunology
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • Dendritic Cells / drug effects
  • Dendritic Cells / immunology*
  • Dendritic Cells / pathology
  • Humans
  • Melanoma / immunology*
  • Melanoma / pathology
  • Melanoma / therapy*
  • Mice
  • Mice, Inbred C57BL
  • Nanocapsules / administration & dosage*
  • Nanocapsules / chemistry
  • Nanocapsules / ultrastructure
  • Poly I-C / administration & dosage*
  • Poly I-C / immunology
  • RNA, Small Interfering / administration & dosage*
  • RNA, Small Interfering / genetics
  • Transfection / methods
  • Treatment Outcome


  • Cancer Vaccines
  • Nanocapsules
  • RNA, Small Interfering
  • Poly I-C