ERH Impacts Patient Prognosis and Tumor Immune Microenvironment: A Pan-Cancer Analysis.

BACKGROUND: The enhancer of rudimentary homolog (ERH) has been shown to play significant roles in tumorigenesis and progression. However, few systematic pan-cancer analyses about ERH have been described.

METHODS: From the tumor immune estimation resource web server2.0 (TIMER2.0), the Genotype-Tissue Expression database (GTEx) and the Gene Expression Profile Interactive Analysis version 2 (GEPIA2) databases, we explored the expression profiles and prognostic significance of ERH in 33 cancers. The Clinical Proteomic Tumor Analysis Consortium (CPTAC) and the Human Protein Atlas (HPA) databases were further used to examine the differential expression of ERH at the protein level. The genetic alteration profile was obtained from the cBioPortal. The correlation between ERH expression and the quantities of immune infiltrating cells was examined by the TIMER tool. Spearman's correlation test was conducted to analyze the association between ERH expression status and a number of prognostic indicators, including immune checkpoints, TMB, MSI, immune neoantigen, MMR genes, and DNA methyltransferases. ProteinProtein Interaction analyses were performed in the String and GeneMANIA databases, and enrichment analysis and predicted signaling pathways were identified through GO and KEGG. To make our results convincing, we validated them in six datasets in the Gene Expression Omnibus (GEO) database. In addition, we verified the expression of ERH between gastric cancer tissues and adjacent normal tissues by RT-qPCR.

RESULTS: ERH expression was elevated in numerous tumors, and it was not associated with the patient's prognosis. Furthermore, the quantities of immune infiltrating cells and immune checkpoint genes were remarkably associated with ERH. TMB and MSI were related to ERH expression in 14 and 15 cancer types, respectively. Moreover, the expression of ERH was strongly associated with MMR defects in multiple cancer types, and almost all tumors showed coexpression of ERH and four DNA methyltransferases. The results of GO and KEGG analysis confirmed that ERH potentially impacts several important signaling pathways. Both the GEO datasets and the RT-qPCR experiment validated our previous analysis.

CONCLUSION: Our pan-cancer analysis demonstrated the characterization of ERH in multiple tumors. ERH may be a valuable novel biological indicator for assessing immunotherapy efficacy and prognosis in various malignancies.