NSUN5/TET2-directed chromatin-associated RNA modification of 5-methylcytosine to 5-hydroxymethylcytosine governs glioma immune evasion.

Malignant glioma exhibits immune evasion characterized by highly expressing the immune checkpoint CD47. RNA 5-methylcytosine(m5C) modification plays a pivotal role in tumor pathogenesis. However, the mechanism underlying m5C-modified RNA metabolism remains unclear, as does the contribution of m5C-modified RNA to the glioma immune microenvironment. In this study, we demonstrate that the canonical 28SrRNA methyltransferase NSUN5 down-regulates ß-catenin by promoting the degradation of its mRNA, leading to enhanced phagocytosis of tumor-associated macrophages (TAMs). Specifically, the NSUN5-induced suppression of ß-catenin relies on its methyltransferase activity mediated by cysteine 359 (C359) and is not influenced by its localization in the nucleolus. Intriguingly, NSUN5 directly interacts with and deposits m5C on CTNNB1 caRNA (chromatin-associated RNA). NSUN5-induced recruitment of TET2 to chromatin is independent of its methyltransferase activity. The m5C modification on caRNA is subsequently oxidized into 5-hydroxymethylcytosine (5hmC) by TET2, which is dependent on its binding affinity for Fe2+ and α-KG. Furthermore, NSUN5 enhances the chromatin recruitment of RBFOX2 which acts as a 5hmC-specific reader to recognize and facilitate the degradation of 5hmC caRNA. Notably, hmeRIP-seq analysis reveals numerous mRNA substrates of NSUN5 that potentially undergo this mode of metabolism. In addition, NSUN5 is epigenetically suppressed by DNA methylation and is negatively correlated with IDH1-R132H mutation in glioma patients. Importantly, pharmacological blockage of DNA methylation or IDH1-R132H mutant and CD47/SIRPα signaling synergistically enhances TAM-based phagocytosis and glioma elimination in vivo. Our findings unveil a general mechanism by which NSUN5/TET2/RBFOX2 signaling regulates RNA metabolism and highlight NSUN5 targeting as a potential strategy for glioma immune therapy.

TAK-242 inhibits glioblastoma invasion, migration, and proneural-mesenchymal transition by inhibiting TLR4 signaling.

Resatorvid (TAK-242), a small-molecule inhibitor of Toll-like receptor 4 (TLR4), has the ability to cross the blood-brain barrier (BBB). In this study, we explored the role of TAK-242 on glioblastoma (GBM) invasion, migration, and proneural-mesenchymal transition (PMT). RNA sequencing (RNA-Seq) data and full clinical information of glioma patients were downloaded from the Chinese Glioma Genome Atlas (CGGA) and the Cancer Genome Atlas (TCGA) cohorts and then analyzed using R language; patients were grouped based on proneural (PN) and mesenchymal (MES) subtypes. Bioinformatics analysis was used to detect the difference in survival and TLR4-pathway expression between these groups. Cell viability assay, wound-healing test, and transwell assay, as well as an intracranial xenotransplantation mice model, were used to assess the functional role of TAK-242 in GBM in vitro and in vivo. RNA-Seq, Western blot, and immunofluorescence were employed to investigate the possible mechanism. TLR4 expression in GBM was significantly higher than in normal brain tissue and upregulated the expression of MES marker genes. Moreover, TAK-242 inhibited GBM progression in vitro and in vivo via linking with PMT, which could be a novel treatment strategy for inhibiting GBM recurrence.