Biology subjects

Akanbi, S.

Publications and source records attributed to Akanbi, S..

2 recordsLinked to original sources

bioRxiv2026

A stromal metabolic program suppresses NK-cell immunity to drive tumor progression in HER2-low breast cancer

Cancer-associated fibroblasts (CAFs) are major regulators of the tumor microenvironment, yet how distinct CAF states suppress innate immunity in HER2-low breast cancer remains poorly understood. Here, we identify an S100A4-enriched CAF population that expands during HER2-low breast tumor progression and establishes a metabolically immunosuppressive niche. Spatial transcriptomics and multiplex imaging of human HER2-low tumors reveal progressive CAF accumulation and an inverse spatial association between S100A4-enriched CAFs and immune infiltration, including natural killer (NK) cells. Using an immunocompetent HER2-low mammary tumor model, we show that S100A4-enriched CAFs promote tumor initiation and progression while suppressing NK-cell cytotoxicity, IFN-{gamma} production, perforin, and granzyme B. Fractionation of CAF-conditioned media and metabolic profiling identify a low-molecular-weight immunosuppressive program characterized by enhanced branched-chain amino acid catabolism and accumulation of branched-chain -keto acids (BCKAs). Mechanistically, BCKAs directly suppress NK-cell IFN-{gamma} production, whereas inhibition of the branched-chain aminotransferase BCAT1 reduces CAF-mediated NK-cell suppression and restores antitumor cytotoxicity. BCAT1 inhibition also suppresses HER2-low tumor growth in vivo, an effect attenuated by NK-cell depletion, establishing NK-cell restoration as a functional component of its antitumor activity. Together, these findings uncover a CAF-driven metabolic immune checkpoint in which S100A4-enriched CAFs exploit BCAT1-dependent BCKA production to suppress NK-cell surveillance and promote HER2-low breast tumor progression. Targeting stromal BCAT1 therefore represents a potential strategy to dismantle CAF-mediated immune suppression and restore innate antitumor immunity.

cancer biology↗

bioRxiv2026

Spatial immune ecosystems govern therapeutic response in HER2-low breast cancer

HER2 low breast cancer represents a clinically important but biologically heterogeneous disease state, and the spatial immune programs underlying therapeutic response remain poorly understood. Here, we used single-cell spatial transcriptomics to characterize HER2 low and HER2 high breast tumors and define microenvironmental features associated with treatment sensitivity and resistance. We identified diverse malignant, stromal, and immune compartments, with dendritic cells emerging as a highly remodeled population in HER2 low tumors. Focused analysis resolved distinct dendritic cell states, including homeostatic cDC2, IFN activated mature cDC, classical functional cDC2, plasmacytoid DC, and ITGAX positive monocyte derived DC populations. Spatial proximity analysis further revealed that resistant HER2 low tumors exhibited increased segregation of tumor epithelial cells from effector immune populations and enrichment of myeloid-rich immune niches, consistent with an immune-restricted spatial architecture. Independent TCGA BRCA validation confirmed the clinical relevance of these dendritic-cell states, with elevated homeostatic cDC2 signatures predicting poor survival, whereas inflammatory dendritic cell signatures were associated with favorable outcomes. Resistant HER2 low tumors were characterized by enrichment of homeostatic and classical cDCs, depletion of IFN-activated cDCs and pDCs, altered tumor myeloid T cell communication, and expansion of spatially organized resistant niches, whereas sensitive tumors retained immune-intermixed niches enriched for antigen presentation and effector immune interactions. Together, these findings demonstrate that therapeutic resistance in HER2 low breast cancer is driven by coordinated spatial remodeling of dendritic-cell states and immune architecture, identifying dendritic cell myeloid niche organization as a potential biomarker and therapeutic vulnerability.

cancer biology↗