An integrated pan-cancer analysis of identifying biomarkers about the EGR family genes in human carcinomas

The early growth response (EGR) family genes, including EGR1, EGR2, EGR3 and EGR4, play important roles in transcriptional regulation and have been reported to be involved in the process of cell growth and apoptosis in a variety of human tumors. However, there have been no systematic pan-cancer analysis about EGR family genes. This study is to clarify the functions and roles of EGR family genes in human pan-cancer. Based on the cancer genome atlas (TCGA) datasets, the University of California Santa Cruz (UCSC) database and several comprehensive bioinformatics methods, we evaluated the expression levels and prognostic values of EGR family genes and explored their relationships with tumor microenvironment (TME), tumor mutation burden (TMB), microsatellite instability (MSI), immune infiltration and immunohistochemistry (IHC). It was found that the expressions of EGR1, EGR2 and EGR3 were abnormally low in 15 cancers, 11 cancers and 13 cancers, respectively, while the expression of EGR4 was abnormally high in 9 cancers and abnormally low in 5 cancers, compared with the corresponding control samples. The expressions of EGR family genes were significantly associated with prognosis, immune score, stromal score, MSI, TMB and immune infiltration for multiple cancers. Moreover, immunohistochemical results manifested that the protein expressions of EGR1 and EGR3 might cause clinical tumor progression in some cancers. These findings elucidated the important roles of the EGR family genes in tumor development and provided clues for further study of the EGR family genes as potential biomarkers in pan-cancer.