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Loss-of-function mutations in genes encoding TET DNA dioxygenase occur frequently in hematopoietic malignancy, but rarely in solid tumors, which instead commonly have reduced activity. The impact of decreased TET activity in solid tumors is not known. Here we show that TET2 mediates the IFN-[gamma]/JAK/STAT signaling pathway to control chemokine and PD-L1 expression, lymphocyte infiltration, and cancer immunity. IFN-[gamma] stimulated STAT1 to bind TET2 and recruit TET2 to hydroxymethylate chemokine and PD-L1 genes. Reduced TET activity was associated with decreased Th1-type chemokines and tumorinfiltrating lymphocytes and the progression of human colon cancer. Deletion of Tet2 in murine melanoma and colon tumor cells reduced chemokine expression and tumor- infiltrating lymphocytes, enabling tumors to evade antitumor immunity and to resist anti-PD-L1 therapy. Conversely, stimulating TET activity by systematic injection of its cofactor ascorbate/vitamin C increased chemokines and tumor-infiltrating lymphocytes, leading to enhanced antitumor immunity and anti-PD-L1 efficacy and extended lifespan of tumor- bearing mice. These results suggest an IFN- [gamma]/JAK/STAT/TET signaling pathway that mediates tumor response to anti-PD- L1/PD-1 therapy and is frequently disrupted in solid tumors. Our findings also suggest TET activity as a biomarker for predicting the efficacy of and patient response to anti-PD-1/PD-L1 therapy, and stimulation of TET activity as an adjuvant immunotherapy of solid tumors., Introduction The ten-eleven translocation (TET) family of proteins, which includes TET1, TET2, and TET3 in mammalian cells, belong to the family of dioxygenases that use [alpha]-ketoglutarate ([alpha]-KG) and reduced iron [...]

Loss-of-function mutations in genes encoding TET DNA dioxygenase occur frequently in hematopoietic malignancy, but rarely in solid tumors which instead commonly have reduced activity. The impact of decreased TET activity in solid tumors is not known. Here we show that TET2 mediates interferon γ (IFNγ)-JAK-STAT signaling pathway to control chemokine and PD-L1 expression, lymphocyte infiltration and cancer immunity. IFNγ stimulated STAT1 to bind TET2 and recruit TET2 to hydroxymethylate chemokine and PD-L1 genes. Reduced TET activity was associated with decreased TH1-type chemokines and tumor-infiltrating lymphocytes (TILs) and the progression of human colon cancer. Deletion of Tet2 in murine melanoma and colon tumor cells reduced chemokine expression and TILs, enabling tumors to evade anti-tumor immunity and to resist anti-PD-L1 therapy. Conversely, stimulating TET activity by systematic injection of its co-factor, ascorbate/vitamin C, increased chemokine and TILs, leading to enhanced anti-tumor immunity and anti-PD-L1 efficacy and extended lifespan of tumor-bearing mice. These results suggest an IFNγ-JAK-STAT-TET signaling pathway that mediates tumor response to anti-PD-L1/PD-1 therapy and is frequently disrupted in solid tumors. Our findings also suggest TET activity as a biomarker for predicting the efficacy and patient response to anti-PD-1/PD-L1 therapy, and stimulating TET activity as an adjuvant immunotherapy of solid tumors. [ABSTRACT FROM AUTHOR]