IL-22 has dual functions during tumorigenesis. Short term IL-22 production protects against genotoxic stress, whereas uncontrolled IL-22 activity promotes tumor growth; therefore, tight regulation of IL-22 is essential. TGF-β1 promotes the differentiation of Th17 cells, which are known to be a major source of IL-22, but the effect of TGF-β signaling on the production of IL-22 in CD4+ T cells is controversial. Here we show an increased presence of IL-17+IL-22+ cells and TGF-β1 in colorectal cancer compared to normal adjacent tissue, whereas the frequency of IL-22 single producing cells is not changed. Accordingly, TGF-β signaling in CD4 + T cells (specifically Th17 cells) promotes the emergence of IL-22-producing Th17 cells and thereby tumorigenesis in mice. IL-22 single producing T cells, however, are not dependent on TGF-β signaling. We show that TGF-β, via AhR induction, and PI3K signaling promotes IL-22 production in Th17 cells.
Pancreatic cancer is an aggressive malignancy resistant to most conventional and experimental therapies, including conditionally replicative adenoviruses (CRAds). The incorporation of immunostimulatory genes such as interleukin-12 (IL-12) in these viruses may overcome some of their limitations, but evaluation of such vectors requires suitable preclinical models. We describe a CRAd in which replication is dependent on hypoxia-inducible factor (HIF) activity and alterations of the pRB pathway in cancer cells. Transgenes (luciferase or IL-12) were incorporated into E3 region of the virus using a selective 6.7K/gp19K deletion. A novel permissive model of pancreatic cancer developed in immunocompetent Syrian hamsters was used for in vivo analysis. We show that, in contrast with nonreplicating adenoviruses (NR-Ad), active viral production and enhanced transgene expression took place in vivo. A single intratumor inoculation of the CRAd expressing IL-12 (Ad-DHscIL12) achieved a potent antitumor effect, whereas higher doses of replication-competent adenoviruses carrying luciferase did not. Compared to a standard NR-Ad expressing IL-12, Ad-DHscIL12 was less toxic in hamsters, with more selective tumor expression and shorter systemic exposure to the cytokine. We conclude that the expression of IL-12 in the context of a hypoxia-inducible oncolytic adenovirus is effective against pancreatic cancer in a relevant animal model.
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