Abstract BS1-2: Neutrophil extracellular traps promote breast cancer metastasis

Abstract

Abstract Cancer cells from a primary tumor can disseminate to other tissues, but remain dormant and clinically undetectable for many years. Little is known about the cues that cause these dormant cells to “awaken”, resume proliferation, and develop into metastases. Using mouse models, we have found that sustained lung inflammation caused by tobacco smoke exposure or nasal instillation of lipopolysaccharide converted disseminated, dormant cancer cells to aggressively growing metastases. Using intravital imaging techniques, which allow for long-term time-lapse imaging of cancer cells and surrounding host cells in living mice, we observed that sustained inflammation induced the formation of neutrophil extracellular traps (NETs). NETs are pathogen-trapping structures generated by expulsion of the neutrophil's DNA with associated proteolytic enzymes in response to e.g., infections. We confirmed that NETs were present in clinical samples of breast cancer lung metastases. Mechanistic analysis revealed that NETs were required for awakening dormant cancer and specifically that two NET-associated proteases, neutrophil elastase and matrix metalloproteinase 9, sequentially cleaved laminin. The proteolytically remodeled laminin induced proliferation of dormant cancer cells by activating integrin alpha-3 beta-1 signaling. We generated antibodies against NET-remodeled laminin and these prevented awakening of dormant cells in mice. In addition, pharmacological inhibition of NET formation or digestion of NETs with DNase I-coated nanoparticles also markedly reduced awakening and lung metastases in mice. Our data suggest that induction of NETs is an important host-mediated mechanism of promoting metastasis and a potential therapeutic target to prevent preventing dormant cell awakening and prolong the survival of cancer patients. Citation Format: Egeblad M. Neutrophil extracellular traps promote breast cancer metastasis [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr BS1-2.