Cancer-Associated Fibroblasts Establish Spatially Distinct Prognostic Niches in Subcutaneous Colorectal Cancer Mouse Model

<b>Background/Objectives</b>: Subcutaneous tumor models are widely used in colorectal cancer (CRC) research due to their experimental accessibility; however, the spatial organization and regulatory mechanisms of their tumor microenvironment remain poorly understood. <b>Methods</b>: Here, we applied spatial transcriptomics to systematically characterize spatial heterogeneity within MC38 subcutaneous tumors in a syngeneic mouse model. <b>Results</b>: We identified two spatially distinct tumor zones, partitioned by cancer-associated fibroblasts (CAFs), that differ markedly in cellular composition, oncogenic signaling, immune infiltration, and metabolic states. One zone exhibited features of TGF-β-driven extracellular matrix remodeling, immune exclusion, and hyperproliferative metabolism, while the other was enriched for immunosuppressive macrophages, metabolic reprogramming via PPAR and AMPK pathways, and high-risk cell populations. Spatially resolved cell-cell communication networks further revealed zone-specific ligand-receptor interactions-such as ANGPTL4-SDC2 and PROS1-AXL-that underpin stromal remodeling and immune evasion and are associated with patient prognosis. <b>Conclusions</b>: Collectively, our study uncovers how region-specific cellular ecosystems and intercellular crosstalk establish prognostically divergent niches within subcutaneous CRC tumors, offering insights into spatially guided therapeutic strategies.