CIS is a potent checkpoint in NK cell-mediated tumour immunity. Mus musculus

Natural killer (NK) cells have evolved to detect and kill aberrant cells with this activity being governed by the cytokine interleukin (IL)-15 and foreign and self-ligands. We have identified CIS (Cytokine-inducible SH2-containing protein; Cish gene) as the critical negative regulator of IL-15 signalling in NK cells. Cish was rapidly induced in response to IL-15 and deletion of Cish rendered NK cells hypersensitive to IL-15, as evidenced by superior proliferation, survival, IFN-γ production and cytotoxicity towards tumours. This was associated with enhanced JAK/STAT signalling in Cish-deleted NK cells. Correspondingly, CIS interacted with the tyrosine kinase JAK1, inhibiting its enzymatic activity and targeting JAK for proteasomal degradation. Cish-/- mice were resistant to melanoma, prostate and breast cancer metastasis in vivo, and this was intrinsic to NK cell activity. This study has uncovered a potent checkpoint in NK cell-mediated tumour immunity and holds promise for novel immunotherapies directed at blocking CIS function. Overall design: Transcriptional profiling of ex vivo and in vitro CIS-/- nature killer cells