Pre-metastatic expression array day 7

Primary tumors have been shown to prepare distal organs for later colonization of metastatic cells by stimulating organ-specific infiltration of bone marrow-derived cells. Here we demonstrate that neutrophils accumulate in the lung prior to the arrival of metastatic cells in mouse models of breast cancer. Tumor-entrained neutrophils (TENs) inhibit metastatic seeding in the lungs by generating H2O2, and tumor-secreted CCL2 is a critical mediator of optimal anti-metastatic entrainment of G-CSF-stimulated neutrophils. TENs are present in the peripheral blood of breast cancer patients prior to surgical resection but not in healthy individuals. Thus, while tumor-secreted factors contribute to tumor progression at the primary site, they concomitantly induce a neutrophil-mediated inhibitory process at the metastatic site.

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Granot Z, Henke E, Comen EA, King TA, Norton L, Benezra R