Transcription factor Zhx2 is a checkpoint that programs macrophage polarization and antitumor response

Macrophages are usually educated to tumor-associated macrophages (TAMs) in cancer with pro-tumor functions by tumor microenvironment (TME) and TAM reprogramming has been proposed as a potential tumor immunotherapy strategy. We recently demonstrated the critical role of Zinc-fingers and homeoboxes 2 (Zhx2) in macrophages' metabolic programming. However, whether Zhx2 is responsible for macrophage polarization and TAMs reprogramming is largely unknown. Here, we show that Zhx2 controls macrophage polarization under the inflammatory stimulus and TME. Myeloid-specific deletion of Zhx2 suppresses LPS-induced proinflammatory polarization but promotes IL-4 and TME-induced anti-inflammatory and pro-tumoral phenotypes in murine liver tumor models. Factors in TME, especially lactate, markedly decrease the expression of Zhx2 in TAMs, leading to the switch of TAMs to pro-tumor phenotype and consequent cancer progression. Notably, reduced ZHX2 expression in TAM correlates with poor survival of HCC patients. Mechanistic studies reveal that Zhx2 associates with NF-?B p65 and binds to the Irf1 promoter, leading to transcriptional activation of Irf1 in macrophages. Zhx2 functions in maintaining macrophage polarization by regulating Irf1 transcription, which may be a potential target for macrophage-based cancer immunotherapy.