Clonal variation in interferon response determines the outcome of oncolytic virotherapy in mouse CT26 colon carcinoma model

Gene Ther. 2015 Jan;22(1):65-75. doi: 10.1038/gt.2014.83. Epub 2014 Sep 18.


In our earlier studies, Semliki Forest virus vector VA7 completely eliminated type I interferon (IFN-I)-unresponsive human U87-luc glioma xenografts, whereas interferon-responsive mouse gliomas proved refractory. Here, we describe in two clones of CT26 murine colon carcinoma, opposed patterns of IFN-I responsiveness and sensitivity to VA7. Both CT26WT and CT26LacZ clones secreted biologically active interferon in vitro upon virus infection but only CT26WT cells were protected. Focal infection of CT26WT cultures was self-limiting but could be rescued using IFN-I pathway inhibitor Ruxolitinib or antibody against IFNβ. Whole transcriptome sequencing (RNA-Seq) and protein expression analysis revealed that CT26WT cells constitutively expressed 56 different genes associated with pattern recognition and IFN-I signaling pathways, spanning two reported anti-RNA virus gene signatures and 22 genes with reported anti-alphaviral activity. Whereas CT26WT tumors were strictly virus-resistant in vivo, infection of CT26LacZ tumors resulted in complete tumor eradication in both immunocompetent and severe combined immune deficient mice. In double-flank transplantation experiments, CT26WT tumors grew despite successful eradication of CT26LacZ tumors from the contralateral flank. Tumor growth progressed uninhibited also when CT26LacZ inoculums contained only a small fraction of CT26WT cells, demonstrating dominance of IFN responsiveness when heterogeneous tumors are targeted with interferon-sensitive oncolytic viruses.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antineoplastic Agents / pharmacology
  • Antineoplastic Agents / therapeutic use
  • Bystander Effect
  • Cell Line, Tumor
  • Colonic Neoplasms / immunology
  • Colonic Neoplasms / pathology
  • Colonic Neoplasms / therapy*
  • Genetic Vectors
  • Green Fluorescent Proteins / biosynthesis
  • Interferon Type I / pharmacology
  • Interferon Type I / therapeutic use
  • Interferon-beta / metabolism
  • Mice, Inbred BALB C
  • Necrosis
  • Neoplasm Transplantation
  • Oncolytic Virotherapy*
  • Oncolytic Viruses / genetics*
  • STAT1 Transcription Factor / metabolism
  • Semliki forest virus / genetics*
  • Transfection
  • Treatment Outcome


  • Antineoplastic Agents
  • Interferon Type I
  • STAT1 Transcription Factor
  • Stat1 protein, mouse
  • enhanced green fluorescent protein
  • Green Fluorescent Proteins
  • Interferon-beta