DNA hypomethylating agents increase activation and cytolytic activity of CD8+ T-cells

DNA hypomethylating agents (HMAs) induce Type I/III interferon signaling through dsRNA-mediated viral mimicry in cancer cells. Yet, the direct effects of HMAs in immune cells remains less clear. Here, we demonstrate that HMA treatments can directly modulate the anti-tumor response and effector function of CD8+ T-cells. In vivo HMA treatment promotes CD8+ T-cell tumor infiltration and supresses tumor growth via CD8+ T-cell dependent activity. HMAs enhances primary human CD8+ T-cells activation markers, effector cytokine production, and anti-tumor cytolytic activity. Epigenomic and transcriptomic profiling shows that HMAs vastly regulate T-cell activation related transcriptional networks, culminating with over-activation of NFATc1 short-isoforms. Mechanistically, demethylation of an intragenic CpG Island immediately downstream to the 3'UTR of the short isoform was associated with anti-sense transcription and alternative polyadenylation of NFATc1 short-isoforms. High-dimensional single-cell mass cytometry (CyTOF) analyses reveal a selective effect of HMAs on a subset of human CD8+ T-cell subpopulations, resulting in an increase in both number and abundance of a granzymeBhigh, perforinhigh effector subpopulation. Overall, our findings support the use of HMAs as a therapeutic strategy to boost anti-tumor immune response. Overall design: ATAC-seq profiling of primary human CD8+ T-cells under the following conditions: unstimulated; stimulated with a-CD3/CD28; stimulated with a-CD3/CD28 and treated with 300 nM Decitabine.