Dual roles of neutrophils in metastatic colonization are governed by the host NK cell status

The role of neutrophils in solid tumor metastasis remains largely controversial. In preclinical models of solid tumors, both pro-metastatic and anti-metastatic effects of neutrophils have been reported. In this study, using mouse models of breast cancer, we demonstrate that the metastasis-modulating effects of neutrophils are dictated by the status of host natural killer (NK) cells. In NK cell-deficient mice, granulocyte colony-stimulating factor-expanded neutrophils show an inhibitory effect on the metastatic colonization of breast tumor cells in the lung. In contrast, in NK cell-competent mice, neutrophils facilitate metastatic colonization in the same tumor models. In an ex vivo neutrophil-NK cell-tumor cell tri-cell co-culture system, neutrophils are shown to potentially suppress the tumoricidal activity of NK cells, while neutrophils themselves are tumoricidal. Intriguingly, these two modulatory effects by neutrophils are both mediated by reactive oxygen species. Collectively, the absence or presence of NK cells, governs the net tumor-modulatory effects of neutrophils.


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Guangwen Ren
Jul 23, 2020 BD FACSDiVa software (version 8) was used for flow cytometry acquisition. Xenogen IVIS image system was used for bioluminescence image collection. Leica Application Suite X (LAS X) software platform was used for image capture from Leica microscopes. Graphpad Prism 7.04 was used for data analysis. FlowJo 10.1 was used for preprocessing of the flow cytometry data and analysis.

nature research | reporting summary
October 2018

Life sciences study design
All studies must disclose on these points even when the disclosure is negative. No data were excluded from the manuscript.
All in vivo, ex vivo and in vitro data are representative of two to three independent experiments. The information is included in the "Statistics and Reproducibility" in the methods section.
All mice were randomized before tumor inoculation.
Except the immunostaining evaluation (Supplementary Figure 2C & 7), all other experiments were unblinded because these analyses were performed using quantifiable parameters and no bias was involved. For example, photon flux of luciferase signal values were used for monitoring the lung metastasis; the luminescence values detected by luminometer were used for in vitro cytotoxic assay; and the values of percentage or number of NK+ cells were derived from flowJo analysis using the same gating strategy.
All of the antibodies used for flow cytometry were purchased from Biolegend, and the dilution for antibodies used in flow cytometric analysis is Note that full information on the approval of the study protocol must also be provided in the manuscript.