Ubiquitinated proteins enriched from tumor cells by a ubiquitin binding protein Vx3(A7) as a potent cancer vaccine

J Exp Clin Cancer Res. 2015 Apr 16;34(1):34. doi: 10.1186/s13046-015-0156-3.

Abstract

Background: Our previous studies have demonstrated that autophagosome-enriched vaccine (named DRibbles: DRiPs-containing blebs) induce a potent anti-tumor efficacy in different murine tumor models, in which DRibble-containing ubiquitinated proteins are efficient tumor-specific antigen source for the cross-presentation after being loaded onto dendritic cells. In this study, we sought to detect whether ubiquitinated proteins enriched from tumor cells could be used directly as a novel cancer vaccine.

Methods: The ubiquitin binding protein Vx3(A7) was used to isolate ubiquitinated proteins from EL4 and B16-F10 tumor cells after blocking their proteasomal degradation pathway. C57BL/6 mice were vaccinated with different doses of Ub-enriched proteins via inguinal lymph nodes or subcutaneous injection and with DRibbles, Ub-depleted proteins and whole cell lysate as comparison groups, respectively. The lymphocytes from the vaccinated mice were re-stimulated with inactivated tumor cells and the levels of IFN-γ in the supernatant were detected by ELISA. Anti-tumor efficacy of Ub-enriched proteins vaccine was evaluated by monitoring tumor growth in established tumor mice models. Graphpad Prism 5.0 was used for all statistical analysis.

Results: We found that after stimulation with inactivated tumor cells, the lymphocytes from the Ub-enriched proteins-vaccinated mice secreted high level of IFN-γ in dose dependent manner, in which the priming vaccination via inguinal lymph nodes injection induced higher IFN-γ level than that via subcutaneous injection. Moreover, the level of secreted IFN-γ in the Ub-enriched proteins group was markedly higher than that in the whole cell lysate and Ub-depleted proteins. Interestingly, the lymphocytes from mice vaccinated with Ub-enriched proteins, but not Ub-depleted proteins and whole cell lysates, isolated from EL4 or B16-F10 tumor cells also produced an obvious level of IFN-γ when stimulated alternately with inactivated B16-F10 or EL4 tumor cells. Furthermore, Ub-enriched proteins vaccine showed a significant inhibitory effect on in vivo growth of homologous tumor, as well as allogeneic tumor, compared with Ub-depleted proteins and tumor cell lysate. Tumor growth was regressed after three times of vaccination with Ub-enriched proteins in contrast to other groups.

Conclusion: These results indicated that Ub-enriched proteins isolated from tumor cells may have a potential as a potent vaccine for immunotherapy against cancer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, Neoplasm / genetics
  • Antigens, Neoplasm / immunology*
  • Antigens, Neoplasm / isolation & purification
  • Cancer Vaccines / immunology*
  • Cell Line, Tumor
  • Female
  • Immunity, Cellular
  • Interferon-gamma / metabolism
  • Lymphoma
  • Melanoma, Experimental
  • Mice
  • Neoplasms / genetics
  • Neoplasms / immunology*
  • Neoplasms / pathology
  • Neoplasms / therapy
  • Ubiquitinated Proteins / genetics
  • Ubiquitinated Proteins / immunology*
  • Ubiquitinated Proteins / isolation & purification

Substances

  • Antigens, Neoplasm
  • Cancer Vaccines
  • Ubiquitinated Proteins
  • Interferon-gamma