AGI-5198

The ribophorin family, including RPN1, has been associated with tumor progression, but its specific role in pan‐cancer dynamics remains unclear. Using data from TCGA, GTEx, and Ualcan databases, we investigated the relationship of RPN1 with prognosis, genomic alterations, and epigenetic modifications across various cancers. Differential analysis revealed elevated RPN1 expression in multiple cancer types, indicating a potential prognostic value. Amplification was the predominant mutation type of RPN1 in pan‐cancer, with notable correlations with DNA methylation and copy number variation. Gene set variation analysis identified RPN1's involvement in cancer development, immunity, and metabolism. Additionally, RPN1 expression correlated with the tumor microenvironment, immune response factors, and response to anti‐tumor therapies. Functional validation in triple‐negative breast cancer, glioblastoma, and bladder cancer cell lines demonstrated the role of RPN1 in tumor cell proliferation and migration. Our findings highlight RPN1 as a potential biomarker for cancer diagnosis and treatment response in pan‐cancer therapy.

Malignant gliomas are heterogeneous tumors, mostly incurable, arising in the central nervous system (CNS) driven by genetic, epigenetic, and metabolic aberrations. Mutations in isocitrate dehydrogenase (IDH1/2 mut ) enzymes are predominantly found in low-grade gliomas and secondary high-grade gliomas, with IDH1 mutations being more prevalent. Mutant-IDH1/2 confers a gain-of-function activity that favors the conversion of a-ketoglutarate (α-KG) to the oncometabolite 2-hydroxyglutarate (2-HG), resulting in an aberrant hypermethylation phenotype. Yet, the complete depiction of the epigenetic alterations in IDH mut cells has not been thoroughly explored. Here, we applied an unbiased approach, leveraging epigenetic-focused cytometry by time-of-flight (CyTOF) analysis, to systematically profile the effect of mutant-IDH1 expression on a broad panel of histone modifications at single-cell resolution. This analysis revealed extensive remodeling of chromatin patterns by mutant-IDH1, with the most prominent being deregulation of histone acetylation marks. The loss of histone acetylation occurs rapidly following mutant-IDH1 induction and affects acetylation patterns over enhancers and intergenic regions. Notably, the changes in acetylation are not predominantly driven by 2-HG, can be rescued by pharmacological inhibition of mutant-IDH1, and reversed by acetate supplementations. Furthermore, cells expressing mutant-IDH1 show higher epigenetic and transcriptional heterogeneity and upregulation of oncogenes such as KRAS and MYC, highlighting its tumorigenic potential. Our study underscores the tight interaction between chromatin and metabolism dysregulation in glioma and highlights epigenetic and oncogenic pathways affected by mutant-IDH1-driven metabolic rewiring.