CD146 + CAFs mediate immunosuppression in gastric cancer via COL4A1: potential therapeutic targets

Background The immunomodulatory roles of cancer-associated fibroblasts (CAFs) in gastric cancer have been increasingly recognized. This study aimed to identify specific CAF subpopulations and to elucidate the mechanisms underlying their immunosuppressive effects. Methods We developed a single-cell RNA sequencing (scRNA-seq) protocol to enrich CAFs and matched normal fibroblasts (NFs) from stomach tissues. Bioinformatics analyses, along with in vitro and in vivo experiments, were performed to functionally validate a distinct CAF subset. Results We profiled 8,322 high-quality fibroblasts from nine patient-matched tumor and adjacent normal tissue pairs. A unique CAF subset, CD146 + CAFs, was identified. CD146 + CAFs were significantly enriched in the tumor microenvironment and associated with poor survival and M2-like macrophage infiltration. Tumor cells promoted CD146 + CAFs expansion via JAG1-NOTCH3 and LGALS3-CD146 signaling. Mechanistically, NOTCH3 acted as a master regulator in CD146 + CAFs. Tumor cell-derived JAG1 engaged NOTCH3 on CD146 + CAFs, which triggered PI3K/AKT-mediated CD146 transcription and enhanced COL4A1 secretion. Functionally, CD146 + CAF-derived COL4A1 bound macrophage CD44/IL7R to drive macrophage M2-like polarization, thereby suppressing CD8 + T-cell function. Therapeutic blockade of CD146 or COL4A1 in vivo impaired M2 polarization, reinvigorated CD8 + T-cell activity, and restrained tumor growth. Conclusions Our findings underscore the pivotal role of CD146 + CAFs in shaping an immunosuppressive microenvironment and highlight CD146 + CAFs and COL4A1 as promising candidates for targeted therapy in gastric cancer.