Metabolic Immunosuppression Mediated by Proliferative CD168+TAMs in Colon Cancer

Abstract

The role of non-monocyte-derived, in situ proliferating tumor associated macrophages (TAMs) in tumor progression has been underappreciated. Proliferative TAM subsets likely represent critical mediators in establishing the immunosuppressive microenvironment, given the susceptibility of TAMs to be hijacked by malignant cells for pro-tumorigenic functions. However, the regulatory networks governing their self-renewal circuitry and lineage bifurcation remained undefined. Combining single cell RNA sequencing of human and murine colon tumors, we identified CD168+ TAMs, a hyperproliferative subpopulation with FOXM1-dependent maintenance of replicative competence. Spatial multi-omics and functional validation revealed that this subset exhibited peritumoral localization and underwent immunosuppressive polarization through cholesterol-coordinated CX3CL1-CX3CR1 signaling. Colon cancer-specific lipid metabolic rewiring elevates glycerophospholipid and cholesterol flux, with PLA2G7-mediated glycerophospholipid catabolism promoting CX3CR1 expression in TAMs. Thus, the CX3CR1 signaling-driven immunosuppressive effect of CD168+ TAM is an integrated response to tumor-specific metabolic features. Targeting the CD168+ TAMs may enable therapeutic strategies for metabolic-immune reshaping in colon cancers.