Neutrophils and their products are increasingly recognized to have a key influence on cancer progression and response to therapy. Their involvement has been shown in nearly every aspect of cancer pathophysiology with growing evidence now supporting their role in resistance to a variety of cancer therapies. Recently, the role of neutrophils in cancer progression and therapy resistance has been further complicated with the discovery of neutrophil extracellular traps (NETs). NETs are web-like structures of chromatin decorated with a variety of microbicidal proteins. They are released by neutrophils in a process called NETosis. NET-dependent mechanisms of cancer pathology are beginning to be appreciated, particularly with respect to tumor response to chemo-, immuno-, and radiation therapy. Several studies support the functional role of NETs in cancer therapy resistance, involving T-cell exhaustion, drug detoxification, angiogenesis, the epithelial-to-mesenchymal transition, and extracellular matrix remodeling mechanisms, among others. Given this, new and promising data suggests NETs provide a microenvironment conducive to limited therapeutic response across a variety of neoplasms. As such, this paper aims to give a comprehensive overview of evidence on NETs in cancer therapy resistance with a focus on clinical applicability.
Lymph nodes (LNs) are frequently the first sites of metastasis. Currently, the only prognostic LN assessment is determining metastasis status. However, there is evidence suggesting that LN metastasis is facilitated by a pre-metastatic niche induced by tumour derived extracellular vehicles (EVs). Therefore, it is important to detect and modify the LN environmental changes. We have previously reported that neutrophil extracellular traps (NETs) can sequester and promote distant metastasis. Here, we first confirmed that LN NETs are associated with reduced patient survival. Next, we demonstrated that NETs deposition precedes LN metastasis and NETs inhibition abolishes LN metastases in animal mode. Furthermore, we discovered that EVs are essential to the formation of LN NETs. Lymphatic endothelial cells secrete CXCL8/2 in response to EVs inducing NETs formation and the promotion of LN metastasis. Our findings are the first to reveal the role of EV induced NETs in LN metastasis and provide potential immunotherapeutic vulnerabilities.
Lymph nodes (LNs) are frequently the first sites of metastasis. Currently, the only prognostic LN assessment is determining metastatic status. However, there is evidence suggesting that LN metastasis is facilitated by the formation of a pre‐metastatic niche induced by tumour derived extracellular vehicles (EVs). Therefore, it is important to detect and modify the LN environmental changes. Earlier work has demonstrated that neutrophil extracellular traps (NETs) can sequester and promote distant metastasis. Here, we first confirmed that LN NETs are associated with reduced patient survival. Next, we demonstrated that NETs deposition precedes LN metastasis and NETs inhibition diminishes LN metastases in animal models. Furthermore, we discovered that EVs are essential to the formation of LN NETs. Finally, we showed that lymphatic endothelial cells secrete CXCL8/2 in response to EVs inducing NETs formation and the promotion of LN metastasis. Our findings reveal the role of EV‐induced NETs in LN metastasis and provide potential immunotherapeutic vulnerabilities that may occur early in the metastatic cascade.
Metastasis is responsible for 90% of all cancer-related deaths, making it the most significant challenge in cancer treatment for clinicians worldwide. Metastasis is thought to occur in a stepwise process, in which local lymph nodes (LNs) are first colonized by tumour cells before proceeding to distal organs. However, the mechanism by which LN metastasis facilitates distal metastasis is poorly understood. LNs undergo environmental changes to accommodate tumour cell growth within, notably by shifting the environment towards immunosuppression to shut down anti-tumour immune cells. This immunosuppressive environment is critical for the establishment of LN metastases, as cytotoxic CD8 T cells will otherwise neutralize incoming circulating tumour cells. Neutrophils are among the first cells recruited to tumour-draining LNs to mediate the environmental shift, and yet their method of action has not been fully elucidated. They have recently been found to secrete NETs within LNs during cancer, which are pro-inflammatory web-like formations of DNA decorated with antimicrobial peptides. While NETs have been shown to exert pro-tumour effects in the tumour microenvironment and to facilitate metastasis as a whole, their role in LNs has never been explored. Using a NETs deficient mouse model (PAD4-/-), we report that NETs deposition within the tumour-draining LNs of mice upregulates the Treg population while simultaneously downregulating anti-tumour CD8 T cell proliferation and activation. Following these findings, we performed an in vitro suppression assay and found that NETs-educated Tregs hinder the expansion of CD8 T cells more than non-NETs-educated Tregs. Finally, through an induced metastasis mouse model, we have observed that tumour-draining LN resection as well as the absence of NETs protects against the development of distal metastasis, and decreases body-wide inflammation as seen by a lowered Neutrophil-to-Lymphocyte ratio in the circulation. Taken together, these findings highlight the role of NETs deposition in LNs as a key player in disease progression and bring forward a potential target for anti-metastatic drug development. Citation Format: Ariane Brassard, Xin Su, Iqraa Dhoparee-Doomah, Sabrina Leo, Lixuan Feng, France Bourdeau, Betty Giannias, Corissa Larson, Qian Qiu, Jonathan Spicer, Lorenzo Ferri, Jonathan Cools-Lartigue. NETs act as immunosuppressive agents within lymph nodes during cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1315.
In most human cancers, regional lymph nodes (LNs) are the first sites of metastasis. In addition to being an important part of the tumor staging system, with the advent of novel therapies, lymph node metastasis has become a crucial clinical intervention point before distant metastasis, the leading cause of cancer-associated deaths. To initiate metastasis, the conditions of LNs need to be optimized for tumor cell deposition and growth. This process is believed to be mediated by the activation of immune cells including polymorphonuclear neutrophils (PMNs), and tumor derived factors, such as extracellular vesicles (EVs). Indeed, tumor derived EVs (tEVs) were shown to prepare sentinel LNs for increased melanoma metastasis, however, the cellular mechanism is not well defined. Early observations suggest that PMNs and neutrophil extracellular traps (NETs), DNA comprising structures that are extruded in response to inflammatory cues, are associated with adverse oncologic outcomes. Moreover, PMNs exhibit considerable plasticity to tEVs, as gastric tEVs can polarize PMN toward a pro-tumor (N2) phenotype and induce NET formation. Thus, one potential mechanism of increased LN metastasis is that tEVs recruit PMNs and propend NETs formation. Here, we show that lymphatic PMN accumulation is associated with higher rates of LN metastasis in human esophageal cancer patients. Furthermore, we demonstrate that LN PMN accumulation is mediated by tEVs-lymphatic interaction both in vitro and in vivo. Finally, we demonstrate that lymphatic PMN facilitate metastasis through the accumulation of PMN prior to tumor ingress. Using Boyden chamber assays, we observed an increase in PMN migration towards tEVs educated lymphatic endothelial cells (LECs). Moreover, ELISA showed tEVs educated LEC increased secretion of the PMN chemoattractants CXCL4 and CXCL8. Additionally, through confocal microscopy and immunofluorescence, we observed that tEVs induced PMN recruitment to LNs and NETs released in vivo in a dose-dependent manner. Finally, using transgenic pad4-/- knockout mice, which are unable to generate NETs, we showed that the absence of NETs led to decreased LN metastasis. Together, these findings highlight the role of tumor derived tEVs both as PMN recruiters to LNs and NETs inducers. By further investigating the detailed mechanism and the efficiency of NETs targeting agents, this project will lead to major advances in the management of cancer patients. Citation Format: Xin SU, Ariane Brassard, Ramin Rohanizadeh, Iqraa Dhoparee-Doomah, Betty Giannias, France Bourdeau, Veena Sangwan, Roni F. Rayes, Jonathan D. Spicer, Lorenzo E. Ferri, Jonathan J. Cools-Lartigue. Cancer extracellular vesicles induce lymph node metastasis via neutrophil extracellular traps [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2863.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.