Study Identifies Molecular Mechanisms Linking Tumor Microenvironment Signals to Immunosuppressive Macrophage States
Researchers systematically exposed human macrophages to cytokines and metabolites found in tumors, profiling the resulting molecular changes to decode how the tumor microenvironment generates immunosuppressive cell states. They found that potassium and adenosine — which accumulate in necrotic tumor cores — suppress antigen-presentation machinery and activate genes linked to immune evasion and metastasis. The findings provide a molecular framework connecting specific tumor signals to clinically observed macrophage populations, with implications for cancer immunotherapy targeting.
A new preprint study systematically stimulated primary human monocyte-derived macrophages with a panel of tumor microenvironment (TME) signals — including cytokines, potassium (K+), and adenosine (Ado) — and profiled transcriptomic and phosphoproteomic responses to map stimulus-specific molecular programs. Potassium stimulation was found to downregulate antigen-presentation genes and their master regulator CIITA, while also upregulating fibronectin 1, a marker associated with immunosuppressive, metastasis-promoting tumor-associated macrophage (TAM) subsets. Adenosine stimulation induced expression of tryptophan catabolism genes, myeloid checkpoint molecules, and metallothioneins (MTs) — a TAM signature recurrently observed in pan-cancer single-cell RNA sequencing datasets but whose function had remained poorly understood. The study found that elevated MT expression in tumor tissue correlates with shorter overall survival in patients. By aligning their in vitro transcriptomes with a pan-cancer TAM atlas, the researchers identified close similarities between adenosine-stimulated macrophages and a clinically observed MT-expressing TAM cluster, offering a reproducible in vitro model for studying these states. The work provides a systematic molecular map linking specific TME cues to clinically relevant immunosuppressive macrophage programs.
What's missing
As a preprint, this work has not yet undergone peer review. The study relies on monocyte-derived macrophages as a model system, which may not fully recapitulate the behavior of tissue-resident or in vivo tumor-associated macrophages. The survival association with MT expression is correlational and does not establish causality. The authors acknowledge that MT-high TAM function remains incompletely characterized, and the mechanisms by which K+ and adenosine suppress CIITA and antigen presentation are not fully resolved.
What different sources said
- bioRxivCenter
Decoding molecular programs that define macrophage responses to tumor-derived cues
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