Neutrophil expression array. Mus musculus

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. This experiment was designed to compare the RNA expression profile in resting (control) neutrophils vs. that of TENs (neutrophils purified from tumor-bearing mice). In addition, we also compared the expression profiles of cultured neutrophils in vitro and treated with CCL2, CCL5 and GCSF. Overall design: Circulating neutrophils were purified from control and 4T1 tumor-bearing mice and flash frozen. For in vitro cultures, circulating neutrophils were purified from control mice, cultured in the presence of chemokines for 2 hours and flash frozen.