The RNA m6A Reader YTHDF2 Maintains Oncogene Expression and Is a Targetable Dependency in Glioblastoma Stem Cells

Area of Science:

• * Molecular Biology
• * Cancer Stem Cell Biology
• * Epitranscriptomics

Background:

• * Glioblastoma (GBM) is a lethal brain cancer driven by glioblastoma stem cells (GSCs).
• * RNA modifications, specifically N⁶-methyladenosine (m6A), play crucial roles in cancer biology.
• * Understanding m6A regulation in GSCs is vital for identifying novel therapeutic targets.

Purpose of the Study:

• * To investigate the role of m6A mRNA modifications and regulators in GSCs.
• * To identify specific dependencies and vulnerabilities within GSCs related to m6A.
• * To explore the YTHDF2-MYC-IGFBP3 axis as a potential therapeutic strategy for glioblastoma.

Main Methods:

• * Methyl RNA immunoprecipitation followed by sequencing (MeRIP-seq) and transcriptome analysis.
• * In vitro and in vivo functional assays to assess YTHDF2 dependency in GSCs.
• * Pharmacological inhibition using linsitinib to target the IGF1/IGF1R pathway.

Main Results:

• * m6A-modified transcripts were frequently upregulated in GSCs compared to normal neural stem cells (NSCs).
• * GSCs showed preferential expression and dependency on the m6A reader YTHDF2, unlike NSCs.
• * YTHDF2 stabilized MYC and VEGFA transcripts in GSCs in an m6A-dependent manner, with IGFBP3 identified as a downstream effector.
• * Linsitinib preferentially inhibited YTHDF2-expressing GSCs, impairing glioblastoma growth in vivo without affecting NSCs.

Conclusions:

• * YTHDF2 links RNA epitranscriptomic modifications to GSC growth and survival.
• * The YTHDF2-MYC-IGFBP3 axis represents a specific and novel therapeutic target for glioblastoma.
• * Targeting YTHDF2 offers a strategy to perturb MYC signaling, a challenging target in glioblastoma therapy.