Expression of IL-27 in murine carcinoma cells produces antitumor effects and induces protective immunity in inoculated host animals

A novel cytokine interleukin-27 (IL-27), composed of p28 and Epstein-Barr virus-induced gene 3 (EBI3), is produced from activated dendritic cells and is involved in an early phase of T-helper type I differentiation. We examined whether Colon 26 murine colon carcinoma cells that were retrovirally transduced with the p28-linked EBI3 gene (Colon 26/IL-27) could produce antitumor effects in inoculated mice. Although proliferation in vitro of Colon 26/IL-27 cells was not different from that of parent cells, syngeneic BALB/c mice rejected Colon 26/IL-27 tumors inoculated and subsequently acquired tumor-specific protective immunity. In contrast, mice inoculated with Colon 26 cells transduced with either the p28 or EBI3 gene developed tumors and survival of the mice remained the same as that of the mice inoculated with parent cells. Syngeneic nude mice developed Colon 26/IL-27 tumors, but the growth was retarded compared to that of parent tumors. Depletion of natural killer cells from nude mice with anti-asialo GM(1) antibody diminished the growth retardation of Colon 26/IL-27 tumors. Survival of severe combined immunodeficient mice that received subcutaneous inoculation of Colon 26/IL-27 cells was not different from that of the immunodeficient mice inoculated with parent cells. Interferon-gamma was produced from CD4(+) and CD8(+) T, and natural killer cells of the mice that rejected Colon 26/IL-27 tumors and cytotoxic activity against Colon 26 cells were also detected from the mice. These data collectively suggest that expressed IL-27 in tumors produces T cell-dependent and-independent antitumor effects and is a possible therapeutic strategy for cancer.