Macrophage Invasion Assay With Pan-Lysyl Oxidase Inhibition

The tumor microenvironment of cholangiocarcinoma features an expansive desmoplastic reaction comprised of dense collagen fibril scaffolds infiltrated with an abundance of immunosuppressive myeloid cells. Together, these components form the underlying framework of tumor stroma that promotes structural and functional resistance to therapy. Lysyl oxidases are a family of 5 secreted copper-dependent amine oxidases (LOX, LOXL1-4) that catalyze collagen and elastin fibrillogenesis. These enzymes have been shown to increase stromal density, facilitate immune evasion, as well as promote tumor growth and metastatic spread. In a murine model of cholangiocarcinoma, we demonstrated reduced myeloid immune suppression following combination of chemotherapy with pan-lysyl oxidase inhibition. In vitro, macrophages exposed to pan-lysyl oxidase inhibition demonstrated reduced invasion towards a stimulus of tumor-conditioned media generated from a novel murine cholangiocarcinoma cell line. We performed RNA sequencing of invasive and non-invasive macrophages following exposure to tumor-conditioned media with or without pan-lysyl oxidase inhibition.