Abstract 2842: Neutrophil migration towards tumor-conditioned media correlates with the malignant potential of breast tumor cells

Abstract

Abstract During tumor development, neutrophils and other immune cells infiltrate the tumor niche. Neutrophils have been shown to have primarily pro-tumorigenic effects, and high levels of circulating neutrophils are indicative of a poor prognosis. Tumor-associated neutrophils (TANs) migrate to tumors by sensing chemical gradients produced by tumor cells; however, the mechanisms by which tumors and TANs interact and impact each other remain to be determined. It has been shown that malignant breast tumors, such as triple-negative breast tumors, harbor more TANs compared to less aggressive breast tumors. We hypothesize that neutrophil recruitment to the tumor niche depends on tumor-secreted, chemotactic factors that are primarily produced by malignant breast tumors. To test this, we used a panel of breast cancer cells grown in monolayers and more physiologically-relevant tumor spheroids, which were formed over the course of four days using the hanging-drop method. We characterized the size and morphology of the spheroids, which were generated from the poorly metastatic BT474 cells, as well as the highly malignant BT549 cells, MDA-MB-231 cells, and M4 cells of the MCF-10A cell series. We then compared the ability of tumor-conditioned media (TCM) isolated from either monolayers or spheroids to stimulate the migration of primary human neutrophils using transwell assays. We found that, compared to TCM isolated from control or poorly metastatic cell lines, the TCM derived from highly malignant cancer cells robustly stimulated the migration of neutrophils. These data indicate that breast cancer cells secrete factors with unique profiles that have varying potentials to recruit neutrophils. We are in the process of identifying specific tumor-secreted factors in the TCM using mass spectrometry. Additionally, we are assessing how the presence of neutrophils affects cancer cell migration and invasion by utilizing a coculture system in which tumor spheroids and primary neutrophils are imaged in real time. We reason that understanding the role of TANs during breast cancer progression will provide insight into novel therapeutic approaches, particularly in the context of highly metastatic forms of the disease. Citation Format: Lauren Hein, Shuvasree SenGupta, Yang Xu, Carole Parent. Neutrophil migration towards tumor-conditioned media correlates with the malignant potential of breast tumor cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2842.