Abstract B009: Tumoral activation of endothelium drives macrophages-mediated metastatic niche formation and promotes lung metastasis

Abstract

Abstract Primary tumor induces macrophages-enriched environment to establish metastatic niche which enhances homing and colonization of circulating tumor cells. However, the molecular mechanism underlying endothelial remodeling that favors macrophages infiltration and subsequent niche formation is not fully understood. Here, we found that tumor-derived factors activated endothelial cells to increase adhesive efficacy of monocytes to the endothelium, leading to macrophage infiltration. In mouse models of pulmonary metastasis, this endothelial activation triggered formation of premetastatic niche via accumulation of macrophages in the lungs. Of note, macrophages primed the metastatic microenvironment through enhancing expression of niche-related genes including S100A8, S100A9, MMP9 and fibronectin within the premetastatic lungs and directly transmitted survival signal to tumor cells in a contact-dependent manner. Furthermore, we demonstrated that depletion of macrophages specifically during premetastatic stages reduced niche formation and also resulted in reduced metastatic burden. These findings suggest that endothelial remodeling at metastatic site is a key step for initiation of premetastatic niche formation supported by macrophages. Targeting this step could present an opportunity for therapeutic intervention of metastatic spread in patients with malignant cancers. Citation Format: Hyewon Chung, Sang Wha Kim, Seung Hyeok Seok. Tumoral activation of endothelium drives macrophages-mediated metastatic niche formation and promotes lung metastasis [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr B009.