Neutrophil extracellular traps induced by neoadjuvant chemotherapy of breast cancer promotes vascular endothelial damage.

Background: The mechanisms underpinning neoadjuvant chemotherapy-induced vascular endothelial injury in breast cancer remain elusive. Our study aims to demonstrate that Neutrophil Extracellular Traps (NETs) play a pivotal role in neoadjuvant chemotherapy-induced vascular endothelial injury in breast cancer, elucidating that chemotherapy-induced upregulation of Solute Carrier 11a1 (Slc11a1) modulates Reactive Oxygen Species (ROS) generation, which may be critical for NETs formation.

Methods: We investigated the impact of neoadjuvant chemotherapy for breast cancer on NETs formation and vascular endothelial injury by analyzing NETs dsDNA and serum markers in patients, cells, and chemotherapy mouse models. RNA sequencing of neutrophils from chemotherapy mouse models was performed to identify the potential NETs formation-associated gene Slc11a1, which was further validated through cellular and animal experiments by assessing Slc11a1 expression, intracellular ferrous ion content, and ROS levels. Knockdown of Slc11a1 in human neutrophils and mouse models were also performed to further confirm the phenotypic results.

Results: Our study revealed that plasma NETs formation and endothelial injury markers were significantly elevated in breast cancer patients undergoing docetaxel & carboplatin (TCb) neoadjuvant chemotherapy, compared to controls. In these patients, NETs formation was associated with the augmentation of endothelial injury markers. Chemotherapy mouse models demonstrated that TCb treatment markedly elevated NETs formation and endothelial injury, which can be mitigated by CI-amidine, a protein-arginine deiminase inhibitor. In human neutrophils, we demonstrated that the TCb chemotherapeutic agents (combination of docetaxel and carboplatin) induced the formation of NETs, which subsequently facilitated damage to human umbilical vein endothelial cells in vitro. RNA sequencing of mouse neutrophils identified Slc11a1 as a key NETs formation-related gene, which was upregulated by TCb chemotherapy in neutrophils, leading to increased intracellular ferrous ion content and ROS generation. Knockdown of Slc11a1 in human neutrophils and mouse models demonstrated its reversal effect on TCb-induced ferrous ion upregulation, ROS generation, and NETs formation.

Conclusions: Our research underscores the capacity of TCb neoadjuvant chemotherapy in breast cancer to augment NETs formation in neutrophils through Slc11a1-mediated ROS generation, which is linked to vascular endothelial injury. Our study elucidates the potential mechanisms underlying perioperative vascular endothelial injury in breast cancer patients undergoing neoadjuvant chemotherapy, offering novel insights into perioperative therapeutic management strategies for these patients.