Activation of p38α stress-activated protein kinase drives the formation of the pre-metastatic niche in the lungs

Primary tumor-derived factors act upon normal cells to generate a pre-metastatic niche, which promotes colonization of target organs by disseminated malignant cells. Here we report that tumor-derived factor-induced activation of the p38α kinase in lung fibroblasts plays a critical role in the formation of a pre-metastatic niche in the lungs and subsequent pulmonary metastases. Activation of p38α led to inactivation of type I interferon signaling and stimulation of expression of fibroblast activation protein. Fibroblast activation protein played a key role in remodeling of the extracellular matrix as well as inducing the expression of chemokines that enable lung infiltration by neutrophils. Increased activity of p38 in normal cells was associated with metastatic disease and poor prognosis in human patients with melanoma, whereas inactivation of p38 suppressed lung metastases. We discuss the p38α-driven mechanisms stimulating the metastatic processes and potential use of p38 inhibitors in adjuvant therapy of metastatic cancers. Gui et al. report that tumor-cell-derived factors induce p38a activation in lung fibroblasts, leading to inactivation of type I interferon signaling, matrix remodeling and neutrophil infiltration, thereby generating a metastasis-permissive niche.