METTL3-mediated m⁶A methylation of E2F2 targets MCU to promote the malignant phenotype of gastric cancer cells.

Gastric cancer (GC) is a highly prevalent malignancy worldwide, and its progression is closely linked to aberrant epigenetic regulation. E2F transcription factor 2 (E2F2), a member of the E2F transcription factor family, has been identified as an oncogene in various cancers. However, the regulatory effects of epigenetic modifications on E2F2 in GC remain incompletely clarified. To address this knowledge gap, the current study was designed to elucidate the impact of Methyltransferase-like 3 (METTL3)-mediated N⁶-methyladenosine (m⁶A) methylation of E2F2 on mitochondrial function in GC cells by regulating the mitochondrial calcium uniporter (MCU). Both in vitro and in vivo analyses revealed a critical oncogenic axis in GC driven by METTL3. This axis, mediated by m⁶A modification, post-transcriptionally stabilizes E2F2 mRNA, resulting in the upregulation of MCU expression and consequent aberrant mitochondrial calcium uptake. Functional assays revealed that activation of the METTL3/E2F2/MCU axis promotes GC cell proliferation and migration and inhibits apoptosis, whereas knockdown of METTL3 or E2F2 reverses these malignant phenotypes. Mechanistically, METTL3 binds to the 3' untranslated region of E2F2 mRNA to enhance its stability, and E2F2 in turn transcriptionally activates MCU expression. Clinical data analysis indicated positive correlations among METTL3, E2F2, and MCU expression, with high levels associated with poor patient prognosis. These findings suggest that targeting the m⁶A modification pathway holds promise for GC therapy, as the newly identified METTL3-E2F2-MCU axis plays a key role in regulating mitochondrial calcium homeostasis.