Chronic stress increases metastasis via neutrophil-mediated changes to the microenvironment

Chronic stress is associated with increased risk of metastasis and poor survival in cancer patients, yet the reasons are unclear. We show that chronic stress increases lung metastasis from disseminated cancer cells 2- to 4-fold in mice. Chronic stress significantly alters the lung microenvironment, with fibronectin accumulation, reduced T cell infiltration, and increased neutrophil infiltration. Depleting neutrophils abolishes stress-induced metastasis. Chronic stress shifts normal circadian rhythm of neutrophils and causes increased neutrophil extracellular trap (NET) formation via glucocorticoid release. In mice with neutrophil-specific glucocorticoid receptor deletion, chronic stress fails to increase NETs and metastasis. Furthermore, digesting NETs with DNase I prevents chronic stress-induced metastasis. Together, our data show that glucocorticoids released during chronic stress cause NET formation and establish a metastasis-promoting microenvironment. Therefore, NETs could be targets for preventing metastatic recurrence in cancer patients, many of whom will experience chronic stress due to their disease. [Display omitted] •Chronic stress increases metastasis in mice•Chronic stress establishes a pro-metastatic lung microenvironment•Deleting the neutrophil-glucocorticoid receptor abolishes stress-induced metastasis•Chronic stress induces metastasis-promoting neutrophil extracellular traps Chronic stress is linked to increased metastasis in cancer patients, but the underlying mechanisms remain unclear. In this study, He et al. show that chronic stress increases metastasis by affecting neutrophils. Chronic stress, via glucocorticoids, alters neutrophils’ circadian rhythm and establishes a metastasis-promoting microenvironment by inducing neutrophil extracellular trap formation.