AUTHOR=Zhang An Zhi , Yuan Xin , Liang Wei Hua , Zhang Hai Jun , Li Ya , Xie Yu Fang , Li Jiang Fen , Jiang Chen Hao , Li Fan Ping , Shen Xi Hua , Pang Li Juan , Zou Hong , Zhou Wen Hu , Li Feng , Hu Jian Ming TITLE=Immune Infiltration in Gastric Cancer Microenvironment and Its Clinical Significance JOURNAL=Frontiers in Cell and Developmental Biology VOLUME=9 YEAR=2022 URL=https://www.frontiersin.org/journals/cell-and-developmental-biology/articles/10.3389/fcell.2021.762029 DOI=10.3389/fcell.2021.762029 ISSN=2296-634X ABSTRACT=

Immunotherapy has developed rapidly and has gradually become one of the important methods for treatment of gastric cancer (GC). The research on tumor infiltrating immune cells (TIICs) and immune-related genes in the tumor microenvironment (TME) greatly encourages the development of immunotherapy. The devolution algorithm (CIBERSORT) was applied to infer the proportion of 22 TIICs based on gene expression profiles of GC tissues, which were downloaded from TCGA and GEO. TCGA was utilized to analyze the differential expression of immune-related genes, and explore the potential molecular functions of these genes. We have observed the enrichment of multiple TIICs in microenvironment of GC. Some of these cells were closely related to tumor mutational burden (TMB), microsatellite instability (MSI), Fuhrman grade, and TNM staging. Survival analysis showed that the infiltration level of CD8+ T cells, activated CD4+ memory T cells and M2 macrophages were significantly related to the prognosis of GC 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. The expression levels of CALCR and PTH1R are strikingly related to the expression of immune checkpoint and the prognosis of GC patients. The type and number of TIICs in microenvironment of GC, as well as immune-related genes are closely related to tumor progression, and can be used as important indicators for patient prognosis assessment.