Paracrine Ovarian Cancer Cell-Derived CSF1 Signaling Regulates Macrophage Migration Dynamics in a 3D Microfluidic Model that Recapitulates in vivo Infiltration Patterns in Patient-Derived Xenografts.

A high density of macrophages in the ovarian cancer microenvironment is associated with disease progression and poor outcomes. Understanding cancer-macrophage interaction mechanisms that establish this pro-tumorigenic microenvironment is critical for developing macrophage-targeted therapies. Here, we utilize three-dimensional microfluidic assays and patient-derived xenografts to define the role of cancer-derived CSF1 on macrophage infiltration dynamics towards ovarian cancer cells. We demonstrate that multiple ovarian cancer models promote the infiltration of macrophages into a 3D extracellular matrix in vitro in a cell density-dependent manner. Macrophages exhibit directional migration and increased migration speed under both direct interactions with cancer cells embedded within the matrix, and paracrine crosstalk with cancer cells seeded in an independent microchannel. We also found that platinum-based chemotherapy increases macrophage recruitment and the levels of cancer cell-derived CSF1. Targeting CSF1 signaling under baseline or chemotherapy-treatment conditions reduced the number of infiltrated macrophages. We further show that results obtained with our 3D microfluidic model reflect the recruitment profiles of macrophages in patient-derived xenografts in vivo. These results highlight the role of CSF1 signaling in establishing macrophage-rich ovarian cancer microenvironments, as well as the utility of microfluidic models in recapitulating 3D tumor ecosystems and dissecting cancer-macrophage signaling. This article is protected by copyright. All rights reserved.