Immune Infiltration in Gastric Cancer Microenvironment and Its Clinical Significance

Background: In recent years, immunotherapy has developed rapidly and has gradually become one of the important methods for treatment of gastric cancer. The research on immune cells and immune-related genes in the tumor microenvironment greatly encourages the development of immunotherapy. Methods : The devolution algorithm (CIBERSORT) was applied to infer the proportion of 22 immune infiltrating cells based on gene expression profiles of gastric cancer tissue, which were downloaded from TCGA and GEO databases. The TCGA database was utilized to analyze the differential expression of immune-related genes, and explore the potential molecular functions of these genes.ResultsWe have observed the enrichment of multiple immune cells in the microenvironment of gastric cancer. Some of these cells are closely related to Fuhrman grade and TNM staging. Survival analysis showed that the infiltration level of CD8 + T cells, activated CD4 + memory T cells and M2 macrophages was significantly related to the prognosis of gastric cancer patients. The functional enrichment analysis of immune-related genes revealed that these genes were mainly associated with cytokine activation and response. Four significant modules were screened by PPI network and 20 key genes were screened from the modules, and the expression levels of CALCR and PTH1R are strikingly related to the prognosis of gastric cancer patients.ConclusionsThe type and number of infiltrating immune cells in the microenvironment of gastric cancer, as well as immune-related genes are closely related to tumor progression, and can be used as important indicators for patient prognosis assessment.