Tumors are complex ecosystems composed of networks of interacting 'normal' and malignant cells. It is well recognized that
cytokine-mediated cross-talk between normal stromal cells, including cancer-associated fibroblasts (CAFs), vascular endothelial cells, immune cells, and
cancer cells, influences all aspects of
tumor biology. Here we demonstrate that the cross-talk between CAFs and
cancer cells leads to enhanced growth of oncolytic virus (OV)-based
therapeutics.
Transforming growth factor-β (TGF-β) produced by
tumor cells reprogrammed CAFs, dampened their steady-state level of
antiviral transcripts and rendered them sensitive to
virus infection. In turn, CAFs produced high levels of
fibroblast growth factor 2 (
FGF2), initiating a signaling cascade in
cancer cells that reduced
retinoic acid-inducible gene I (RIG-I) expression and impeded the ability of malignant cells to detect and respond to virus. In xenografts derived from individuals with
pancreatic cancer, the expression of
FGF2 correlated with the susceptibility of the
cancer cells to OV
infection, and local application of
FGF2 to resistant
tumor samples sensitized them to virotherapy both in vitro and in vivo. An OV engineered to express
FGF2 was safe in
tumor-bearing mice, showed improved therapeutic efficacy compared to parental virus and merits consideration for clinical testing.