IFN-γ-STAT1-mediated NK2R expression is involved in the induction of antitumor effector CD8 + T cells in vivo.

The induction of antitumor effector T cells in the tumor microenvironment is a crucial event for cancer immunotherapy. Neurokinin receptor 2 (NK2R), a G protein-coupled receptor for neurokinin A (NKA), regulates diverse physiological functions. However, the precise role of NKA-NK2R signaling in the antitumor immunity is unclear. Here, we found that an IFN-γ-STAT1 cascade augmented NK2R expression in CD8 + T cells, and NK2R-mediated NKA signaling was involved in inducing antitumor effector T cells in vivo. The administration of a synthetic analog of double-stranded RNA, polyinosinic-polycytidylic acid (poly I:C), into a liver cancer mouse model induced type-I and type II IFNs and significantly suppressed the tumorigenesis of Hepa1-6 liver cancer cells in a STAT1-dependent manner. The reduction in tumor growth was diminished by the depletion of CD8 + T cells. IFN-γ stimulation significantly induced NK2R and tachykinin precursor 1 (encodes NKA) gene expression in CD8 + T cells. NKA stimulation combined with anti-CD3 monoclonal antibody (mAb) treatment significantly augmented IFN-γ and granzyme B production by CD8 + T cells compared with the anti-CD3 mAb alone in vitro. ERK1/2 phosphorylation and IκBα degradation in activated CD8 + T cells were suppressed under NK2R deficiency. Finally, we confirmed that tumor growth was significantly increased in NK2R-deficient mice compared with that in wild-type mice, and the antitumor effects of poly I:C were abolished by NK2R absence. These findings suggest that IFN-γ-STAT1-mediated NK2R expression is involved in the induction of antitumor effector T cells in the tumor microenvironment, which contributes to the suppression of cancer cell tumorigenesis in vivo.