Malignant cell-secreted chemokines drive colorectal cancer progression through endothelial cell activation

Cell interactions within the tumor microenvironment (TME) fundamentally reshape the immune landscape, influencing clinical phenotypes in colorectal cancer (CRC). In this study, we integrated single-cell RNA sequencing (scRNA-seq), inference of copy number variations (inferCNV), and non-negative matrix factorization (NMF) to decipher the TME dynamics in 26 CRC patients, stratified by their T stages (T2, T3, T4a). Malignant cells, characterized via inferCNV, exhibited specific immune-related patterns in the most advanced T4a stage, identified through NMF. Genes involved in guiding chemotaxis showed either increasing or decreasing activity as the tumor stage progressed. Four candidate genes (CXCL1, CXCL2, CXCL3, and GDF15) were prioritized, with their elevated expression levels correlating with tumor invasion. Further analysis pinpointed C-X-C motif chemokine ligand 2 (CXCL2) as a critical factor. CXCL2 serves as a canonical ligand for atypical chemokine receptor 1 (ACKR1), and their interaction is vital for immune cells to move into inflammatory sites. In T4a CRC, CXCL2 derived from malignant cells acts on ACKR1 enriched at junctions of endothelial cells (ECs). Knockdown of either CXCL2 in LoVo cells or ACKR1 in human umbilical vein endothelial cells (HUVECs) significantly inhibited cancer cell migration toward ECs. Collectively, these findings indicate that as CRC advances, increased secretion of CXCL2 from malignant cells stimulates ACKR1 on ECs, thereby promoting tumor invasion and metastasis. This study provides a framework for stage-specific interventions, particularly for locally advanced CRC, by disrupting ACKR1 on ECs within TME to impede metastasis and improve clinical outcomes.