Characterization of T-Cell Ubiquitination in Melanoma and Development of a Risk Signature Using Single-Cell and Bulk RNA-Seq.

Cutaneous melanoma (CM) is an aggressive cancer where early intervention is crucial, but the prognostic role and mechanisms of ubiquitination-related genes (URGs) in immune regulation remain unclear. This study aimed to develop a URG-based prognostic signature and explore its relationship with immune modulation in CM. We integrated single-cell RNA sequencing (scRNA-seq) and bulk RNA-seq data, identifying prognostic URGs through univariate and multivariate Cox regression. A six-gene signature (UBE2L6, SPSB1, PSMB9, PSMB10, RNF213 and ATXN3) was established and validated. The signature effectively stratified patients into high- and low-risk groups, with significant survival differences. Pathway analysis revealed immune-related processes, such as 'cytokine-cytokine receptor interaction' and 'antigen processing and presentation', enriched in the low-risk group. Immune cell infiltration analysis demonstrated significant differences in the abundance of 12 immune cell types between risk groups. Notably, PSMB9 expression was positively correlated with CD8+ T cell abundance (r = 0.64, p < 0.05). scRNA-seq analysis highlighted T cells as a key cell type, with all six prognostic genes showing dynamic expression changes during T cell differentiation. Our findings suggest that URGs influence CM prognosis by modulating the immune microenvironment, offering new insights for immunotherapeutic strategies.