METTL4-mediated nuclear N6-deoxyadenosine methylation promotes metastasis through activating multiple...

Area of Science:

• Epigenetics
• Cancer Biology
• Molecular Oncology

Background:

• Nuclear DNA N6-methyldeoxyadenosine (6mA) is rare in mammalian cells, with its function largely unknown.
• The role of 6mA in cancer progression and metastasis requires further elucidation.

Purpose of the Study:

• To investigate the role of nuclear 6mA modification in hypoxia-induced cancer progression.
• To identify the molecular mechanisms linking hypoxia, 6mA, and tumor metastasis.
• To evaluate METTL4 and 6mA as potential prognostic markers and therapeutic targets.

Main Methods:

• RNA sequencing to identify hypoxia- and METTL4-regulated genes.
• 6mA chromatin immunoprecipitation-exonuclease digestion followed by sequencing (6mA-ChIP-seq) to map 6mA modifications.
• Quantitative chromatin isolation by RNA purification (qChIRP) assay to assess lncRNA-chromatin interactions.
• Gene knockdown experiments to determine functional roles.

Main Results:

• Hypoxia induces nuclear 6mA modification mediated by DNA methyltransferase METTL4.
• METTL4 and 6mA co-expression is a prognostic marker for upper tract urothelial cancer.
• Identification of lncRNA RP11-390F4.3 and ZMIZ1 as co-regulated targets of hypoxia and METTL4.
• METTL4-mediated 6mA deposition activates metastasis-inducing genes, including EMT regulators, via lncRNA-chromatin interactions.
• ZMIZ1 is identified as a crucial co-activator of HIF-1α.

Conclusions:

• Hypoxia enriches nuclear 6mA levels in mammalian tumor cells through METTL4.
• METTL4-mediated 6mA deposition promotes tumor metastasis by activating metastasis-associated genes.
• METTL4 represents a potential therapeutic target for hypoxic tumors.