Mutant p53 shapes the enhancer landscape of cancer cells in response to chronic immune signaling

Abstract

Inflammation influences cancer development, progression, and the efficacy of cancer treatments, yet the mechanisms by which immune signaling drives alterations in the cancer cell transcriptome remain unclear. Using ChIP-seq, RNA-seq, and GRO-seq, here we demonstrate a global overlap in the binding of tumor-promoting p53 mutants and the master proinflammatory regulator NFκB that drives alterations in enhancer and gene activation in response to chronic TNF-α signaling. We show that p53 mutants interact directly with NFκB and that both factors impact the other’s binding at diverse sets of active enhancers. In turn, the simultaneous and cooperative binding of these factors is required to regulate RNAPII recruitment, the synthesis of enhancer RNAs, and the activation of tumor-promoting genes. Collectively, these findings establish a mechanism by which chronic TNF-α signaling orchestrates a functional interplay between mutant p53 and NFκB that underlies altered patterns of cancer-promoting gene expression.

Protein Cofactors Are Essential for High-Affinity DNA Binding by the Nuclear Factor κB RelA Subunit

“…Previous reports had already shown that these oncogenic p53 proteins bind RelA like p53 wt. 32 These data suggest that oncogenic versions of p53 that are defective in their DNA binding might retain their ability to interact with RelA and, consequently, influence the expression of RelA target genes by enhancing the DNA binding of NF- κ B, even when nuclear RelA levels are low.…”

“…31,32 We first tested whether the entire p53 protein is necessary or if one particular structural domain of p53 is sufficient to enhance recombinant rBac-RelA:DNA binding. EMSA analysis revealed that the p53 DNA binding domain (DBD) is effective in stimulating the DNA binding activity of RelA, although the full length protein appeared to be most effective (Figure 4a,b).…”

“…18,19,31,32,43 Conversely, RelA, as well as other NF- κ B subunits, can modulate the DNA binding properties of other transcription factors. 42,43 Thus, in addition to their well-studied direct DNA binding properties, each of these transcription factors appears to function in the nucleus as a signaling cofactor that influences the DNA binding and transcriptional potential of their binding partners even at locations within the genome where no consensus DNA binding site for the cofactor is present.…”

Mutant p53-Associated Molecular Mechanisms of ROS Regulation in Cancer Cells

“…The ability of mutant p53 to establish an inflammatory tumor microenvironment is mainly dependent on a functional interaction with NF-κB. In fact, mutant p53 has been shown to promote an efficient and prolonged NF-κB transcriptional activity in various cancer cells stimulated with TNFα, resulting in immune cell infiltration and inflammation [158][159][160][161]. In this way, it has been demonstrated that the inflammatory stimulus led by mutant p53 increases the incidence of invasive colon carcinoma in a mouse model of chronic colitis [160].…”

“…These studies support the existence of different mechanisms induced by mutant p53 proteins to modulate the expression of secreted inflammatory cytokines in order to sustain an inflammatory tumor microenvironment, thus potentially contributing to promote oxidative stress and increased cancer aggressiveness. [110,117,118,120,121] R175H, R248W, R273H NF-kB Lung, pancreatic, breast and colon cancer [158][159][160][161][162] R175H, R281G, R273H Cytokines Lung, breast, pancreatic and colon cancer [157,164,165] R175H, R273H PGC1-α Lung, colon and pancreatic cancer [8,137] R175H, R280K, R273H NRF2 Colon carcinoma, oesophageal adenocarcinoma, lung and breast cancer [133][134][135] R175H, R273H AMPK Pancreatic and breast cancer [8,89,110] R175H, R248H, R273H SESNs Breast and pancreatic cancer [8,89] R175H, R273H UCP2 Lung, pancreatic and breast cancer [8] R175H, R273H GSH Oesophageal adenocarcinoma, pancreatic and breast cancer [128,135] R175H, R273H Autophagy Lung carcinoma, pancreatic and breast cancer [89]…”