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MIF-CD74 Signaling Defines a Brain-Specific Immune Vulnerability in Metastasis and Neurologic Disease
Eunmi Lee1,2, Yibin Kang1,2,3
1Department of Molecular Biology, Princeton University, Princeton, New Jersey.
Abstract:
Brain metastases represent a major clinical challenge in systemic cancer, as current treatments are rarely curative and neurologic morbidity dominates patient outcomes. Increasing evidence suggests that the brain functions as a distinct, partially orthogonal ecosystem in which therapeutic success at extracranial sites fails to translate into effective intracranial tumor control, implicating brain-specific microenvironmental programs in disease progression. In this issue of Cancer Research, Álvaro-Espinosa and colleagues redefine the immune molecule CD74, classically viewed as a marker of antigen presentation, as a key component of a brain-induced, disease-promoting myeloid program. A CD74+ macrophage population emerges specifically during metastatic colonization and is activated by tumor-derived macrophage migration inhibitory factor (MIF). MIF-CD74 signaling drives NF-κB activation and establishes a metabolically sustained prometastatic state linked to oxidative phosphorylation and OMA1-mediated mitochondrial plasticity. Importantly, this pathway represents a viable therapeutic target. The MIF-CD74 inhibitor, ibudilast, suppresses brain metastatic tumor growth in mouse models and shows efficacy across patient-derived organotypic cultures from multiple tumor origins. Extending beyond cancer, CD74+ brain macrophages are also observed in other neurologic pathologies, highlighting shared, pan-disease microenvironmental programs mediated by CD74+ macrophages across diverse brain disorders. See related article by Alvaro-Espinosa et al., p. 3249.
Insights
Researchers identified CD74 as a key driver in brain metastasis, promoting tumor growth through macrophage activation. Targeting the MIF-CD74 pathway with ibudilast shows promise in suppressing brain tumors and offers potential for treating various brain disorders.
Area of Science:
- Immunology
- Neuroscience
- Oncology
Background:
- Brain metastases pose significant challenges in cancer treatment, with poor patient outcomes.
- The brain's unique microenvironment often hinders the efficacy of systemic cancer therapies.
- Brain-specific programs are implicated in the progression of metastatic disease within the central nervous system.
Purpose of the Study:
- To investigate the role of the immune molecule CD74 in brain metastasis.
- To identify novel therapeutic targets for intracranial tumors.
- To explore shared microenvironmental mechanisms in diverse brain disorders.
Main Methods:
- Characterization of CD74 expression in macrophages during metastatic colonization.
- Analysis of the interaction between macrophage migration inhibitory factor (MIF) and CD74.
- Assessment of downstream signaling pathways, including NF-κB and mitochondrial plasticity.
- Evaluation of the therapeutic efficacy of a MIF-CD74 inhibitor (ibudilast) in preclinical models and patient-derived cultures.
Main Results:
- A specific CD74-positive macrophage population emerges during brain metastatic colonization.
- MIF-CD74 signaling activates NF-κB and promotes a prometastatic state via oxidative phosphorylation and mitochondrial changes.
- Ibudilast effectively suppresses brain metastatic tumor growth in mouse models.
- The therapeutic strategy demonstrated efficacy in patient-derived organotypic cultures from various cancer origins.
Conclusions:
- CD74 is a critical component of a brain-induced myeloid program that promotes cancer metastasis.
- The MIF-CD74 signaling pathway is a viable therapeutic target for brain metastases.
- CD74+ macrophages mediate shared programs in both cancer and other neurologic pathologies, suggesting broader therapeutic potential.
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