Abstract 628: Liver macrophages promote breast cancer liver metastasis through migrating neutrophils and initiating NETosis

Abstract Neutrophils extracellular traps (NETs), which are DNA scaffolds in complex with granule proteins, could be detected in the pre-metastatic liver niches and were associated with a poor survival in breast cancer patients. However, the mechanisms of neutrophils infiltration and NETs formation in the pre-metastatic liver tissues remain poorly understood. Here, we dynamically characterized the liver micro-environment of normal and 4T1-bearing BALB/C mouse models with or without liver metastasis by the single cell RNA sequencing. Interestingly, we found that CXCL1 and CXCL2, derived from the liver macrophages, were dramatically elevated in pre-metastatic livers and induced the infiltration of peripheral neutrophils by CXCR2. Besides, liver macrophages were educated by cancer cells-derived cathepsin C to secrete the CXCL1 and CXCL2. Furthermore, we identified that the complement signals were over-activated in pre-metastatic livers and induced neutrophils to NETosis. Therapeutically, targeting CXCL1, CXCL2 and complement signals could inhibit the NET formation and effectively reduce breast cancer liver metastasis. Citation Format: Heliang Li, Linbin Yang, Erwei Song. Liver macrophages promote breast cancer liver metastasis through migrating neutrophils and initiating NETosis [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 628.