Loss of p53 dictates Wnt-dependent systemic inflammation in breast cancer

Cancer-associated inflammatory processes in the tumour microenvironment, as well as systemically, are strongly linked with poor disease outcome in cancer patients. For most human solid tumour types, high systemic neutrophil-to-lymphocyte ratios (NLR) are associated with increased metastasis and poor overall survival and recent experimental studies have demonstrated a causal relationship between neutrophils and metastasis formation. However, to date, the cancer cell-intrinsic mechanisms dictating the substantial heterogeneity in systemic neutrophilic inflammation between tumour-bearing hosts are largely unresolved. Using a panel of 16 distinct genetically engineered mouse models (GEMMs) for breast cancer, we demonstrate that tumour cell-intrinsic loss of p53 changes the phenotype and function of macrophages in the microenvironment, leading to activation of a systemic inflammatory cascade that drives neutrophil expansion. Mechanistically, p53 loss in cancer cells induces secretion of Wnt ligands that act in a paracrine fashion to stimulate IL-1b production from tumour-associated macrophages. Intratumoural IL-1ß production stimulates an inflammatory cascade leading to the systemic accumulation of neutrophils. Pharmacological and genetic blockade of cancer cell-derived Wnt secretion reverses IL-1ß expression by macrophages and subsequent systemic neutrophilic inflammation. Collectively, using pre-clinical mouse models for breast cancer, we demonstrate a novel mechanistic link between loss of p53 in cancer cells, Wnt ligand secretion and systemic immune activation. This illustrates the importance of cancer cell-intrinsic genetic aberrations in dictating cancer-associated inflammation. These insights set the stage for personalized immune intervention strategies for cancer patients. Overall design: In this study, gene expression profiles of tumours from genetically engineered mouse models (GEMMs) were analysed using RNA sequencing. Analysis was performed on bulk tumours of 10 GEMMs with different tissue-specific mutations driving tumorigenesis, totalling to 125 different tumours (n=5 or more per group). Subsequently, samples were grouped according to p53 status of the tumour (models containing Trp53 floxed alleles, or not) and comparisons were made between p53-KO and p53-WT tumours.

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Wellenstein MD, Coffelt SB, Duits DEM, van Miltenburg MH, Slagter M, de Rink I, Henneman L, Kas SM, Prekovic S, Hau CS, Vrijland K, Drenth AP, de Korte-Grimmerink R, Schut E, van der Heijden I, Zwart W, Wessels LFA, Schumacher TN, Jonkers J, de Visser KE