Pro-inflammatory cytokine/chemokine production by reovirus treated melanoma cells is PKR/NF-κB mediated and supports innate and adaptive anti-tumour immune priming

Mol Cancer. 2011 Feb 21;10:20. doi: 10.1186/1476-4598-10-20.

Abstract

Background: As well as inducing direct oncolysis, reovirus treatment of melanoma is associated with activation of innate and adaptive anti-tumour immune responses.

Results: Here we characterise the effects of conditioned media from reovirus-infected, dying human melanoma cells (reoTCM), in the absence of live virus, to address the immune bystander potential of reovirus therapy. In addition to RANTES, IL-8, MIP-1α and MIP-1β, reovirus-infected melanoma cells secreted eotaxin, IP-10 and the type 1 interferon IFN-β. To address the mechanisms responsible for the inflammatory composition of reoTCM, we show that IL-8 and IFN-β secretion by reovirus-infected melanoma cells was associated with activation of NF-κB and decreased by pre-treatment with small molecule inhibitors of NF-κB and PKR; specific siRNA-mediated knockdown further confirmed a role for PKR. This pro-inflammatory milieu induced a chemotactic response in isolated natural killer (NK) cells, dendritic cells (DC) and anti-melanoma cytotoxic T cells (CTL). Following culture in reoTCM, NK cells upregulated CD69 expression and acquired greater lytic potential against tumour targets. Furthermore, melanoma cell-loaded DC cultured in reoTCM were more effective at priming adaptive anti-tumour immunity.

Conclusions: These data demonstrate that the PKR- and NF-κB-dependent induction of pro-inflammatory molecules that accompanies reovirus-mediated killing can recruit and activate innate and adaptive effector cells, thus potentially altering the tumour microenvironment to support bystander immune-mediated therapy as well as direct viral oncolysis.

MeSH terms

  • Adaptive Immunity / drug effects
  • Adaptive Immunity / immunology
  • Cell Line, Tumor
  • Chemokines / biosynthesis*
  • Chemokines / metabolism
  • Chemotaxis / drug effects
  • Culture Media, Conditioned / pharmacology
  • Dendritic Cells / cytology
  • Dendritic Cells / drug effects
  • Dendritic Cells / immunology
  • Humans
  • Immunity / drug effects
  • Immunity / immunology*
  • Immunity, Innate / drug effects
  • Immunity, Innate / immunology
  • Inflammation Mediators / metabolism*
  • Killer Cells, Natural / cytology
  • Killer Cells, Natural / drug effects
  • Killer Cells, Natural / immunology
  • Lymphocyte Activation / drug effects
  • Melanoma / enzymology
  • Melanoma / immunology*
  • Melanoma / metabolism
  • Melanoma / virology
  • NF-kappa B / metabolism*
  • Phenotype
  • Reoviridae / drug effects
  • Reoviridae / immunology*
  • Reoviridae Infections / immunology
  • T-Lymphocytes, Cytotoxic / cytology
  • T-Lymphocytes, Cytotoxic / drug effects
  • T-Lymphocytes, Cytotoxic / immunology
  • eIF-2 Kinase / metabolism*

Substances

  • Chemokines
  • Culture Media, Conditioned
  • Inflammation Mediators
  • NF-kappa B
  • eIF-2 Kinase