Med12 ablation promotes anti-tumor function by enhancing tumor intrinsic immunogenicity in Pancreatic ductal adenocarcinoma [human RNA-seq]

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers with limited treatment options, including checkpoint blockade (ICB) immunotherapy. Epigenetic dysregulation is a defining feature of tumorigenesis and contributes to immune escape. However, little is known about whether and how epigenetic regulators evade immune surveillance in PDAC. Here, we identified Med12, a subunit of RNA polymerase II, as a mediator of immune escape in PDAC with in vivo CRISPR-Cas9 Screening. In murine PDAC models, Med12 loss effectively promoted infiltration and cytotoxicity of CD8+ T cells and NK cells，thereby sensitized to ICB and led to a marked extension of survival. Mechanistically, Med12 loss derepressed endogenous retroelements via impairing H3K9me3 and increasing H3K27Ac modification, triggering cytosolic RNA-sensing and DNA-sensing pathways as well as the type I interferon pathways. Moreover, Med12 depletion induced H3K27Ac gain in the Med12-binding domains, further enhanced the interferon-related genes transcription. Our results demonstrated the role of Med12 in suppressing tumor-intrinsic immunogenicity, thus provided a potential target or marker for immunotherapy of PDAC. To investigate the function of Med12 regulating tumor instrinsic immunogenicity, wo conducted Med12 KO and WT cell lines. Then, we performed RNA sequencing to analyse gene expression profile of Med12 KO and WT cells.