Complex interaction of tumor-derived factors instructs the niche specific phenotypes of tumor-associated macrophages (in vitro human macrophage RNA-Seq)

Despite the pivotal role of tumor-associated macrophages (TAMs) in modulating anti-tumor immunity, the conserved patterns and molecular determinates for the formation of diverse TAM subsets remain largely elusive. In this study, we uncovered the exclusive distribution of pro-angiogenic and MHC-II programs of TAMs are well-conserved, and identified key genes and pathways required for macrophage polarization by tumor cells by CRISPR screen. Notably, we demonstrated that multiple TAM phenotypes were mainly shaped by the synergistic and antagonistic interactions between GM-CSF, PGE2, and lactic acid. We further found the inactivation of Adar, an RNA-editing enzyme, reprograms TAMs into an ISG+ phenotype characterized by the high expression of immune stimulatory genes, thereby enhancing the anti-tumor immune response. Thus, our study illuminates the molecular principles underlying the generation and rewiring of TAM functional phenotypes. Overall design: To investigate the effects of lactate, PGE2, and GM-CSF on the polarization of human macrophages, we isolated CD14+ monocytes from peripheral blood mononuclear cells (PBMCs) of healthy donors and differentiated them into macrophages. We then examined how these molecules influence human macrophage phenotypes and functions.