Abstract 4518: IL-4/IL-13 stimulated tumor-associated macrophages enhance breast cancer cell invasion through Rho-GTPase signaling

Abstract

Abstract The high metastatic potential of inflammatory and other aggressive breast cancer is the major determinant of mortality. Recently, it has become clear that signals from the tumor microenvironment (TME) harbor the capacity to enhance cancer cell dissemination. Of the various cells that comprise the TME, macrophages are the most abundant in solid tumors. Therefore, we aimed to better understand the relationship between macrophage-breast cancer cell crosstalk. Intriguingly, in our previous work we showed that inflammatory breast cancer (IBC) cells are hyper-migratory in response to macrophage conditioned media. Additionally, we found this process is regulated by the Rho-GTPase, RhoC. Recent advances in tumor associated macrophage (TAM) biology have led to the understanding that TAM populations in the TME are diverse, primarily due to directional differentiation promoted by unique secreted components from the various cells in the TME. Therefore, this study aimed to understand which subpopulation of M2-like TAMs had the greatest impact on breast cancer cell aggressiveness. Our data show that stimulation of the triple negative breast cancer (TNBC) cell model, MDA-MB-231, and the IBC TNBC cell line, SUM-149, with media extracts from IL-4/IL-13 stimulated M2 macrophages (M2a) elicit the strongest migratory and invasive responses. Subsequently, we stimulated RhoA or RhoC knockout (CRISPR) MDA-231 and SUM-149 cells with M2a conditioned media to address their role in regulating migratory/invasive responses. In brief, we find that RhoA and RhoC, in part, regulate M2a-TAM induced responses. Secretome analysis of M2a-TAM conditioned media reveals high levels of vascular endothelial growth factor (VEGF) and chemokine (C-C motif) ligand 18 (CCL-18). Functional studies suggest that VEGF and CCL-18 synergistically enhance cellular invasiveness. Moreover, pretreatment with the ROCK inhibitor Y-27632 or GSK429286A drastically inhibited VEGF, CCL-18, or M2a induced migratory responses. These data suggest that the Rho-GTPases regulate M2a-mediated breast cancer cell invasion and potentially offer a novel approach for the treatment of metastatic breast cancer through potential prevention of progression. Citation Format: Andrew C. Little, Pragathi Pathanjeli, Zhifen Wu, Liwei Bao, Laura Goo, Joel A. Yates, Sofia D. Merajver. IL-4/IL-13 stimulated tumor-associated macrophages enhance breast cancer cell invasion through Rho-GTPase signaling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4518.