Immune cell infiltration plays an essential role in the occurrence and development of
colon cancer. However, the main
tumor-associated immune cell infiltration and its gene regulation in
colon cancer still need to be further clarified in order to provide a new perspective for diagnosing and treating this disease. For this study, single-cell
RNA sequencing (
scRNA-seq) expression profiles and TCGA
colon cancer data sets were first acquired from the GEO database. Then, Seurat, Monocle, LIMMA, Clusterprofile, GSVA and GSEABase algorithms were used to systematically examine the data. Potential target drugs corresponding to target genes were analyzed in the Drugbank database and detected by molecular docking. Immunohistochemistry was used to assess the level of C1QC expression in the tissue microarray. Single cell analysis suggested that neutrophil activation might be the critical regulatory pathway in
colon cancer and that macrophages were the main cell population involved. Subsequent functional enrichment analysis on differential genes in macrophages suggested that C1QC may be a critical regulatory factor in the occurrence and progression of
colon cancer, and was closely related to the survival of patients. According to the
drug target prediction,
palivizumab is a targeted
drug for C1QC, and molecular docking demonstrated that
palivizumab binds to C1QC. Additionally, tissue-microarray based immunohistochemical analysis showed that C1QC was highly expressed in
colon cancer tissue, and the prognosis of
colon cancer patients with high C1QC expression was worse, closely related to age,
lymphatic metastasis and the TNM stage (
Tumor, Nodes and
Metastases). Our findings suggest that C1QC may regulate the macrophages in
colon cancer immune infiltration, which is expected to be a potential
immunotherapy target for
colon cancer, and beneficial for the diagnosis and prognosis of
colon cancer patients.