Glioblastoma (GBM) is among the most aggressive primary brain tumors, despite advances in surgical and adjuvant therapies, GBM patients often surviving less than two years after diagnosis. The exploration of new therapeutic targets and novel genes to alter the prognosis of GBM patients holds significant importance. Here, we identified RNF135, a ring-finger protein-encoding gene, as a potential immune-related biomarker and therapeutic target in GBM.

We integrated high-throughput RNA-sequencing data from multiple public databases, including The Cancer Genome Atlas (TCGA), Chinese Glioma Genome Atlas (CGGA), and the IVY Glioblastoma Atlas Project. Bulk transcriptomic data were used for survival analyses and gene function analyses. Immune infiltration was assessed using MCP-counter, xCell and ssGSEA. Single-cell RNA-sequencing data from GSE131928 were utilized to provide cellular resolution of RNF135 expression among tumor-associated macrophage (TAM) subtypes, while bulk RNA-sequencing data from the IVY Glioblastoma Atlas were used to validate its spatial distribution within distinct anatomical regions of GBM. Drug sensitivity analysis was conducted to explore effective treatment options for the RNF135-high patient group.

High RNF135 expression was strongly associated with poor overall survival. Immune deconvolution analyses revealed that RNF135-high tumors exhibit increased infiltration of T cells, NK cells, monocyte-derived macrophages, and myeloid-derived suppressor cells (MDSCs). Notably, single-cell RNA sequencing data showed that RNF135 is enriched in aggressive TAM subsets, specifically monocyte-derived TAM and proliferative TAM, suggesting a role in immunosuppression and tumor angiogenesis. Validation using the IVY Glioblastoma Atlas confirmed that RNF135 is predominantly expressed in highly vascularized tumor niches, particularly in microvascular proliferation (CT.mvp) and highly vascularized (CT.hbv) regions. Gene set enrichment analysis (GSEA) demonstrated significant enrichment of inflammatory and oncogenic pathways, including KRAS, IL6-JAK-STAT3, and TNFalphaα-NFkappaκB, which support RNF135’s involvement in tumor progression. Finally, drug sensitivity analyses indicated that RNF135-high tumors may be more responsive to MEK inhibition (e.g., selumetinib), aligning with the observed enrichment of KRAS-driven pathways.

Our study identifies high RNF135 expression in GBM is strongly associated with poor prognosis, increased immune infiltration, and an immunosuppressive tumor microenvironment. RNF135 could serve as both prognostic marker and potential target for precision therapy. Further comprehensive experimental validation and clinical investigations are warranted to explore RNF135-targeted therapeutic strategies in GBM.