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.

Overcoming therapeutic resistance in oncolytic herpes virotherapy by targeting IGF2BP3-induced NETosis in malignant glioma.

Oncolytic virotherapy holds promise for cancer treatment, but the factors determining its oncolytic activity remain unclear. Neutrophil extracellular traps (NETs) are associated with cancer progression, yet their formation mechanism and role in oncolytic virotherapy remain elusive. In this study, we demonstrate that, in glioma, upregulation of IGF2BP3 enhances the expression of E3 ubiquitin protein ligase MIB1, promoting FTO degradation via the ubiquitin-proteasome pathway. This results in increased m6A-mediated CSF3 release and NET formation. Oncolytic herpes simplex virus (oHSV) stimulates IGF2BP3-induced NET formation in malignant glioma. In glioma models in female mice, a BET inhibitor enhances the oncolytic activity of oHSV by impeding IGF2BP3-induced NETosis, reinforcing virus replication through BRD4 recruitment with the CDK9/RPB-1 complex to HSV gene promoters. Our findings unveil the regulation of m6A-mediated NET formation, highlight oncolytic virus-induced NETosis as a critical checkpoint hindering oncolytic potential, and propose targeting NETosis as a strategy to overcome resistance in oncolytic virotherapy.

Melittin inhibits tumor cell migration and enhances cisplatin sensitivity by suppressing IL-17 signaling pathway gene LCN2 in castration-resistant prostate cancer.

BACKGROUND: Melittin is a small molecule polypeptide extracted from the abdominal cavity of bees, which is used to treat inflammatory diseases and relieve pain. However, the antitumor effect of melittin and its mechanisms remain unclear, especially in castration-resistant prostate cancer (CRPC). METHODS: Through CCK-8 assay, colony formation assay, wound healing assay and Transwell migration assay, we explored the effect of melittin on CRPC cell lines. In addition, with microarray analysis, gene ontology analysis and kyoto encyclopedia of genes and genomes analysis, this study identified key genes and signaling pathways that influence the growth of PC-3 cells. Meanwhile, the effect of melittin on CRPC was also verified through subcutaneous tumor formation experiments. Finally, we also tested the relevant indicators of human prostate cancer (PCa) specimens through immunohistochemistry and H＆E stating. RESULTS: Here, melittin was verified to inhibit the cell proliferation and migration of CPRC. Moreover, RNA-sequence analysis demonstrated that Interleukin-17 (IL-17) signaling pathway gene Lipocalin-2 (LCN2) was downregulated by melittin treatment in CRPC. Further investigation revealed that overexpression of LCN2 was able to rescue tumor suppression and cisplatin sensitivity which melittin mediated. Interestingly, the expression of LCN2 is highly related to metastasis in PCa. CONCLUSIONS: In brief, our study indicates that LCN2 plays an oncogenic role in CRPC and melittin may be selected as an attractive candidate for CRPC therapy.

Therapeutic targeting m6A-guided miR-146a-5p signaling contributes to the melittin-induced selective suppression of bladder cancer.

Abnormal RNA methylation and dysregulation of miRNA are frequently occurred in bladder cancer. Melittin is a potential drug candidate for intravesical chemotherapy against bladder cancer. However, the underlying epigenetic mechanism by which melittin-induced anti-tumor effect remains unclear. Here, we showed that melittin selectively induced apoptosis of bladder cancer cells in a METTL3-dependent manner. Ectopic expression of METTL3 significantly blocked melittin-induced apoptosis in vitro and in vivo. MicroRNA-sequence analysis identified miR-146a-5p suppression contributed to the melittin-induced selective antitumor effect. Further investigation revealed that METTL3-guided m6A modification methylated pri-miR-146 at the flanking sequence, which was responsible for the pri-miR-146 maturation. Moreover, NUMB/NOTCH2 axis was identified as a downstream target signal that mediated the pro-survival role of miR-146a-5p in bladder cancer cells. Importantly, METTL3 and miR-146a-5p were positively correlated with recurrence and poor prognosis of patients with bladder cancer. Our study indicates that METTL3 acts as a fate determinant that controls the sensitivity of bladder cancer cells to melittin treatment. Moreover, METTL3/miR-146a-5p/NUMB/NOTCH2 axis plays an oncogenic role in bladder cancer pathogenesis and could be a potential therapeutic target for recurrent bladder cancer treatment.

miRNA-182-5p promotes human bladder cancer proliferation and migration through the FOXF2/SHH axis.

Increasing evidence suggests that microRNAs (miRNAs) play critical roles in bladder tumorigenesis and development by combining with the 3' untranslated regions (3'-UTRs) of the corresponding mRNAs to negatively regulate gene expression. The role of miR-182-5p in bladder cancer (BC) remains unclear. Therefore, this study aimed to clarify the functional role of miR-182-5p in BC. We predicted candidate mRNAs for miR-182-5p via three databases (TarBase, ENCORI, and miRDB). Dual-luciferase reporter assays and target prediction confirmed FOXF2 as a potential target of miR-182-5p. Quantitative RT-PCR (qRT-PCR) showed that endogenous miR-182-5p expression was significantly upregulated in BC cell lines and clinical samples of BC patients. IHC, western blotting, and qRT-PCR assays indicated that FOXF2 expression was concurrently downregulated in BC tissues and BC cell lines. Gain- and loss-of-function studies showed that the overexpression of miR-182-5p enhanced the proliferation and migration of BC cells, while the downregulation of miR-182-5p showed the opposite results. The effects induced by miR-182-5p were attenuated with the restoration of FOXF2 expression. In BC cells, the upregulation of miR-182-5p not only decreased FOXF2 expression but also markedly increased Sonic hedgehog (SHH) pathway levels. These findings suggested that FOXF2 directly binds to miR-182-5p and that miR-182-5p acts as a tumor promoter in BC genesis and metastasis by targeting FOXF2. In addition, miR-182-5p plays a pro-cancer role by downregulating FOXF2 and activating the SHH pathway.