Tumor Microenvironment-induced BRD4 Activation Results in Chromatin Remodeling and Therapy Resistance in Colorectal Cancer [ChIP-seq]

Tumor microenvironment promotes tumorigenesis, but its role in modulating tumor chromatin activity is poorly understood. Here, we show that inflammatory cytokines interleukin-6 and -8 in the tumor microenvironment induces JAK2-mediated phosphorylation of bromodomain-containing protein 4 (BRD4), which results in interaction with UCHL3 deubiquitinase, leading to increased BRD4 protein stabilization in colorectal cancer. JAK2-phosphorylated BRD4 shows enhanced activity binding to chromatin but reduced binding to BRD4 inhibitors, leading to treatment resistance. Moreover, BRD4 phosphorylation promotes interaction with STAT3 to induce chromatin remodeling through concurrent binding to enhancers and super-enhancers, supporting a tumor-promoting transcriptional program. Thus, the inflammatory tumor microenvironment provides a powerful mechanism for tumor chromatin remodeling and oncogenic transcription, which suggests a unrecognized new strategy to enhance BRD4 inhibitor response. Overall design: Examination of 4 differents transcription/epigenetic regulators in patient-derived colorectal cancer cells with/without IL6/8 treatment.