Loss of p53 triggers Wnt-dependent systemic inflammation to drive breast cancer metastasis

Cancer-associated systemic inflammation is strongly linked with poor disease outcome in cancer patients(1,2). For most human epithelial tumour types, high systemic neutrophil-to-lymphocyte ratios are associated with poor overall survival(3), and experimental studies have demonstrated a causal relationship between neutrophils and metastasis(4,5). However, 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 have uncovered a novel role for cancer cell-intrinsic p53 as a key regulator of pro-metastatic neutrophils. Mechanistically, p53 loss in cancer cells induced secretion of Wnt ligands that stimulate IL-1β production by tumour-associated macrophages, which drives systemic inflammation. Pharmacological and genetic blockade of Wnt secretion in p53-null cancer cells reverses IL-1β expression by macrophages and subsequent neutrophilic inflammation, resulting in reduced metastasis formation. Collectively, we demonstrate a novel mechanistic link between loss of p53 in cancer cells, Wnt ligand secretion and systemic neutrophilia that potentiates metastatic progression. These insights illustrate the importance of the genetic makeup of breast tumours in dictating pro-metastatic systemic inflammation, and set the stage for personalized immune intervention strategies for cancer patients.