<i>IRF1</i> expression might be a biomarker of CD8+ T cell infiltration in cutaneous melanoma

This study aimed to explore the expression profile of interferon regulatory factor (IRF) genes in skin cutaneous melanoma (SKCM), their association with CD8 + T cell infiltration, and the potential regulatory network in melanoma and non-melanoma cells. Bioinformatic analysis was conducted using the SKCM subset of The Cancer Genome Atlas (TCGA) Pan-Cancer, Genotype-Tissue Expression Project (GTEx), and single-cell RNA-seq data from the Human Protein Atlas and Jerby-Arnon et al. 2018ʹs dataset. <i>IRF1</i> expression is robustly associated with moderate to strong CD8 + T cell infiltration in the tumor microenvironment. It is ubiquitously expressed in tumor and non-tumor cells in melanoma. Melanoma tumor cells and macrophages had 16/36 and 9/27 cell-specific <i>IRF1</i>-correlated genes, respectively. The methylation of four CpG sites (cg00255919, cg21138405, cg15375424, and cg27587780) within the <i>IRF1</i> gene locus showed moderate to strong negative correlations with <i>IRF1</i> expression. <i>IRF1</i> expression might serve as a biomarker indicating CD8 + T cell infiltration in skin melanoma. It might exert different regulatory effects in melanoma and non-melanoma cells in the tumor microenvironment. Cg00255919, cg21138405, cg15375424, and cg27587780 are four critical CpG sites that might modulate the transcription of <i>IRF1</i>.