Senescent Neutrophils Fuel Colon Cancer Spread to Liver by Blocking Immunity

Colorectal cancer liver metastasis (CRLM) accounts for over 70% of colorectal cancer deaths, yet immune checkpoint therapies have shown limited benefit in this setting. Understanding the immune microenvironment of CRLM—particularly the role of neutrophils—could unlock new therapeutic strategies.

Using a microwell-based single-cell RNA sequencing platform optimized for low-transcript cells, the researchers profiled over 50,000 neutrophils from six CRLM patients. Integrating single-cell data with spatial-enhanced-resolution omics sequencing (Stereo-seq) and transgenic mouse models, they mapped the transcriptional landscape of tumor-associated neutrophils (TANs) across primary colorectal tumors, adjacent liver tissue, and liver metastases.

The study identified four TAN subsets. TAN1, the most clinically significant, displayed a senescent-like phenotype with upregulated glycolysis genes, cell cycle arrest markers, and the transcription factor BHLHE40. TAN1 was significantly enriched in liver metastases compared to primary tumors and was associated with worse relapse-free and overall survival in a cohort of 127 CRLM patients. Spatial transcriptomics confirmed TAN1 co-localization with angiogenic and immunosuppressive zones within metastatic lesions.

Mechanistically, glucose deprivation in the metastatic microenvironment upregulates BHLHE40, driving TAN1 differentiation from other TAN subsets. Functionally, TAN1 promotes angiogenesis by secreting VEGFA and recruits immunosuppressive macrophages through CCL3L1–CCR1 ligand-receptor signaling, creating a vascular immunosuppressive niche that facilitates tumor immune evasion. Neutrophil-specific knockout of Bhlhe40 in mouse CRLM models significantly boosted antitumor CD8+ T-cell responses and suppressed metastatic tumor growth, validating the therapeutic potential of targeting this pathway.

These findings establish BHLHE40+ senescent-like neutrophils as key architects of the CRLM immunosuppressive microenvironment and suggest that neutrophil-directed interventions—particularly targeting BHLHE40 or the CCL3L1–CCR1 axis—could complement existing immunotherapy approaches in patients with CRLM.