METTL3 inhibition attenuates AFB1-induced hepatic fibrosis by suppressing m6A-mediated hepatic stellate cell activation.

BACKGROUND

Aflatoxin B1 (AFB1) is a potent hepatotoxic mycotoxin and a major environmental risk factor for hepatocellular carcinoma (HCC). Hepatic fibrosis is a critical intermediate stage in this process, and METTL3-mediated m6A modification may represent an important post-transcriptional mechanism linking AFB1-induced liver injury to fibrogenic progression.

METHODS

AFB1-induced hepatic fibrosis was evaluated using in vivo mouse models and in vitro cultured hepatic stellate cells (HSC). Global m6A methylation and methyltransferase-like 3 (METTL3) expression were assessed by liquid chromatography-mass spectrometry, Western blotting, single-nucleus RNA sequencing, and quantitative real-time PCR. METTL3 was inhibited using small interfering RNA or the selective inhibitor STM2457. Molecular docking was performed to identify potential METTL3-binding compounds, followed by functional validation.

RESULTS

AFB1 exposure promoted hepatic fibrosis and HSC activation, accompanied by global m6A hypermethylation and upregulation of METTL3. METTL3 increased the m6A modification of collagen-related transcripts, enhancing their stability and promoting extracellular matrix production in a YTHDF1-dependent manner. Inhibition of METTL3 suppressed HSC activation and fibrotic gene expression both in vitro and in vivo. Molecular docking identified saxagliptin as a potential METTL3-binding compound, which reduced AFB1-induced HSC activation and extracellular matrix accumulation, consistent with the effects of STM2457.

CONCLUSIONS

These findings indicate that METTL3 functions as a post-transcriptional regulator in AFB1-induced liver fibrosis via m6A modification. METTL3 inhibition, achieved via genetic knockdown or selective inhibitors, affects HSC activation and fibrotic gene expression, supporting its role as a therapeutic target in AFB1-induced liver fibrosis.