Analysis of immune microenvironment and immune-related differentially expressed genes related to prognosis in metastatic colorectal cancer / 肿瘤研究与临床

ABSTRACT

Objective:To analyze the difference in immune microenvironment between primary tumor tissues and metastatic tumor tissues of metastatic colorectal cancer, and to screen specific immune-related differentially expressed genes (DEG) related to prognosis of metastatic colorectal cancer via bioinformatics methods.Methods:The GSE131418 microarray dataset of colorectal cancer and metastases was downloaded from gene expression omnibus (GEO) database, including 517 samples from the MCC cohort and 618 samples from the Consortium cohort in Moffitt Cancer Center. Immune-related gene sets were downloaded from immunology database and analysis portal IMMPORT, including 2 483 immune-related genes. A total of 695 cases of RNA sequencing data and 627 cases of clinical information of colorectal cancer tumors and adjacent tissues were downloaded from Cancer Genome Atlas (TCGA) data. The stroma cell score, immune cell score and stromal immune total score of metastatic tumor tissues and primary tumor tissues were calculated by using ESTIMATE algorithm, and 22 kinds of immune cell infiltration in primary tumor and metastatic tumor tissues of colorectal cancer were compared and analyzed by using CIBERSORT deconvolution algorithm. Immune-related DEG were screened to make Kyoto Encyclopedia of Genes and Gnomes (KEGG) signaling pathway enrichment analysis. The patients were divided into high and low expression groups according to the median expression levels of immune-related DEG. The Kaplan-Meier method and Cox regression risk model were used to analyze immune-related DEG, and the genes significantly related to prognosis in the results of the two methods were screened (all P < 0.01), and multivariate analysis was performed by using Cox regression method. The expression differences of each gene in tumor tissues, adjacent tissues, primary tumor tissues and metastatic tissues in GSE131418 data sets of TCGA database and GEO database were compared, and survival analysis was also performed. Results:The stroma cell score, immune cell score and stromal immune total score of colorectal cancer metastatic tissues were lower than those of primary tumor tissues (all P < 0.001). Compared with primary tumor tissues, the proportion of activated natural killer (NK) cells, monocytes, CD8 + T cells, T cells, activated dendritic cells in metastatic colorectal cancer tissues was increased, while the proportion of inactive mast cells, inactive dendritic cells, inactive NK cells, activated memory CD4 + T cells, M1 macrophages, and neutrophils was decreased. There were 289 immune-related DEG in metastatic tissues and primary tumor tissues of metastatic colorectal cancer, including 101 up-regulated genes and 188 down-regulated genes. KEGG signaling pathway enrichment analysis showed that in the immune microenvironment of metastatic tissues in metastatic colorectal cancer, vascular endothelial growth factor (VEGF) signaling pathway, programmed death ligand 1 (PD-L1) expression and programmed death 1 (PD-1) checkpoint pathway, T helper cell (Th) 1, Th2 and Th17 cell differentiation, NF-kappa B signaling pathway, interleukin 17 (IL-17) signaling pathway, chemokine signaling pathway, T cell receptor signaling pathway, MAPK signaling pathway, and NK cell-mediated cytotoxicity pathways enrichment were detected. Immune-related DEG related to prognosis including ANGPTL5, FPR1, HSPA8, NR2E3, PSMD2, PSMD8 and SBDS were screened out. Cox regression multivariate analysis showed that immune-related DEG ANGPTL5 ( HR = 2.69, 95% CI 1.22-5.92, P < 0.05), HSPA8 ( HR = 0.57, 95% CI 0.33-0.97, P < 0.05), and SBDS ( HR = 2.23, 95% CI 1.18-4.21, P < 0.05) were independent prognostic factors for metastatic colorectal cancer. The expression of ANGPTL5 in tumor tissues was lower than that in normal tissues, and the expression of ANGPTL5 in metastatic tissues was higher than that in primary tumor tissues. Patients with high expression of ANGPTL5 in tumor tissues had worse prognosis. The expression of HSPA8 in tumor tissues was higher than that in normal tissues, and the expression of HSPA8 in metastatic tissues was lower than that in primary tumor tissues. Patients with high expression of HSPA8 in tumor tissues had a better prognosis. The expression of SBDS in tumor tissues was lower than that in normal tissues, and the expression of SBDS in metastatic tissues was lower than that in primary tumor tissues. Patients with high expression of SBDS in tumor tissues had worse prognosis. Conclusions:Immune microenvironment of metastatic colorectal cancer is quite different from that of primary tumor. The degree of immune cell infiltration is reduced and the whole is immunosuppressed. The specific immune-related DEG related to prognosis of metastatic colorectal cancer may be new therapeutic targets of metastatic colorectal cancer.