Establishing METTL16 as a key regulator of GBM carcinogenesis

Glioblastoma multiforme (GBM) is the most aggressive and lethal primary brain tumor in adults, characterized by rapid cell proliferation, pronounced heterogeneity, and an infiltrative behavior that complicates clinical management. Despite advancements in diagnostics and molecular biology, the standard treatment—surgical resection followed by radiotherapy and temozolomide— has yielded only modest improvements in outcomes, with median survival remaining around 14 16 months. Tumor-intrinsic resistance, genetic and phenotypic plasticity, and the restrictive blood brain barrier continue to pose significant challenges. Therefore, there is a pressing need for novel therapeutic strategies. Recently, N6-methyladenosine (m6A) RNA modification has emerged as a crucial regulator of gene expression. The m6A mark is controlled by a coordinated network of “writers,” “erasers,” and “readers.” METTL16 is a relatively new m6A writer that has attracted increasing attention due to its involvement in multiple cancer types. Accumulating evidence indicates that METTL16 is overexpressed in various malignancies and plays a key role in tumorigenesis and the maintenance of the neoplastic phenotype. 1 This study investigates the oncogenic role of METTL16 in GBM. Based on RNA-seq data analysis from publicly available databases (TCGA and GTEx), we identified a significant overexpression of METTL16 in glioblastoma (GBM) patient samples compared with normal brain tissues. These findings were subsequently validated in vitro, confirming elevated METTL16 expression in GBM cell lines relative to normal human astrocytes (NHA). Knockdown experiments in GBM cell lines (T98G and U87) demonstrated that METTL16 depletion significantly reduces proliferation, clonogenic potential, and metabolic activity, while inducing apoptosis and causing marked cytotoxicity in vitro. Pharmacological inhibition of METTL16 recapitulated the phenotype observed upon gene silencing and induced profound transcriptomic alterations. In particular, RNA sequencing of cells treated with a METTL16 inhibitor identified mTOR signaling as a downstream target, with broad downregulation of related pathways, suggesting the existence of a potential METTL16–mTOR axis. In conclusion, our findings identify METTL16 as a critical regulator of GBM cell survival and proliferation, highlighting its potential as a novel therapeutic target in glioblastoma multiforme.