Background
Considering the involvement of CC-chemokine receptor type 7 (CCR7) in diverse tumors, the
Conclusion
CCR7 was highly-expressed in ESCC and positively correlated with KRAS signaling up, which may contribute to the migration of ESCC cells.
Methods
We processed single-cell RNA sequencing data based on the Gene Expression Omnibus (GEO) database and utilizing Seurat software, and performed filtering and annotation to obtain different cell types. Genes related to gene ontology biological process and Hallmark were collected, and the enrichment of genes of interested in both single cell and TCGA-ESCA was quantified. Besides, genes related to CCR7 and KRAS signaling up were uploaded to construct the protein-protein interaction network. A series of cellular assays were incorporated to test the effects of CCR7 in ESCC cells.
Results
28,281 cells were categorized into 4 non-immune cell classes (epithelial cells, smooth muscle cells, fibroblasts, endothelial cells) and 6 immune cell classes (mast cells, plasma B cells, B cells, neutrophils, macrophages, NK/T cells). CCR7 evidently expressed higher in epithelial cells of ESCA and was positively correlated with KRAS signaling up, inflammatory response and TNFA signaling via NFKB, with the most significant correlation witnessed between CCR7 and KRAS signaling up. Meanwhile, the positive correlation between KRAS signaling up and positive regulation of epithelial cell migration was observed. 12 common genes were related to both KRAS signaling up and positive regulation of epithelial cell migration, 3 of which (SOX9, FLT4 and HDAC9) were higher-expressed in M1 group of TCGA-ESCA. Besides, CCR7 as well as its ligands CCL19 and CCL21 was shown to express higher in ESCC cells, where increased level of immune response-related cytokines was seen. CCR7 knockdown diminished migration and proliferation as well as Macrophage M2 polarization.