Neutrophil extracellular traps sequester circulating tumor cells and promote metastasis
Jonathan Cools-Lartigue, … , Paul Kubes, Lorenzo Ferri
Jonathan Cools-Lartigue, … , Paul Kubes, Lorenzo Ferri
Published July 1, 2013
Citation Information: J Clin Invest. 2013;123(8):3446-3458. https://doi.org/10.1172/JCI67484.
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Research Article Oncology

Neutrophil extracellular traps sequester circulating tumor cells and promote metastasis

Abstract

The majority of patients with cancer undergo at least one surgical procedure as part of their treatment. Severe postsurgical infection is associated with adverse oncologic outcomes; however, the mechanisms underlying this phenomenon are unclear. Emerging evidence suggests that neutrophils, which function as the first line of defense during infections, facilitate cancer progression. Neutrophil extracellular traps (NETs) are extracellular neutrophil-derived DNA webs released in response to inflammatory cues that trap and kill invading pathogens. The role of NETs in cancer progression is entirely unknown. We report that circulating tumor cells become trapped within NETs in vitro under static and dynamic conditions. In a murine model of infection using cecal ligation and puncture, we demonstrated microvascular NET deposition and consequent trapping of circulating lung carcinoma cells within DNA webs. NET trapping was associated with increased formation of hepatic micrometastases at 48 hours and gross metastatic disease burden at 2 weeks following tumor cell injection. These effects were abrogated by NET inhibition with DNAse or a neutrophil elastase inhibitor. These findings implicate NETs in the process of cancer metastasis in the context of systemic infection and identify NETs as potential therapeutic targets.

Authors

Jonathan Cools-Lartigue, Jonathan Spicer, Braedon McDonald, Stephen Gowing, Simon Chow, Betty Giannias, France Bourdeau, Paul Kubes, Lorenzo Ferri

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Figure 3

Tumor cell adhesion after CLP is augmented by trapping within neutrophil-derived extracellular DNA.

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Tumor cell adhesion after CLP is augmented by trapping within neutrophil...
In order to demonstrate that tumor cells become embedded within NETs, SD-IVM was performed permitting visualization of (A) hepatic sinusoids in living mice and (B) pulmonary capillaries ex vivo within 10 minutes. Images shown in A and B represent a single 3-dimensional reconstruction of confocal z-stacks (10- to 20-μm thickness,1-μm intervals), rotated 180° from an inferior to a superior perspective. In both liver and lungs, tumor cells (red) were found to arrest within extracellular chromatin (Alexa Fluor 555 anti-histone H2AX [green]) adjacent to neutrophils (E-fluor 660 anti-GR1 [blue]). Scale bars: 20 μm. See also Supplemental Video 1 and Supplemental Figure 3. (C) Quantification of adhesion of H59 cells within hepatic sinusoids. 3 × 104 cells were injected via the spleen 24 hours after CLP or sham surgery. Adhesion was increased after CLP compared with sham. Systemic administration of DNAse 1 or NEi starting 1 day prior to CLP abolished this increase. (D) Quantification of B16 melanoma cells within pulmonary capillaries. 1 × 106 cells were injected via tail vein 24 hours after CLP or sham. Adhesion was increased after CLP compared with sham and was abolished by administration of DNAse 1 or NEi starting 1 day prior to CLP. Quantification was performed by counting the number of cells per hpf in 8 to 10 hpf (×20) per experiment. Data are presented as mean ± SEM from n = 5 mice per group. ***P < 0.001 versus sham, DNAse, and NEi as determined by 1-way ANOVA with Tukey’s HSD post-hoc analysis.