METTL16-SENP3-LTF axis confers ferroptosis resistance and facilitates tumorigenesis in hepatocellular carcinoma

Ferroptosis, characterized by iron-dependent lipid peroxidation, emerges as a promising avenue for hepatocellular carcinoma (HCC) intervention due to its tumor susceptibility. RNA N6-methyladenosine (m6A) modification has been involved in several types of regulated cell death. However, the roles and molecular mechanisms of m6A-related regulators in HCC cell ferroptosis remain unclear. By examining a series of m6A modification enzymes upon ferroptosis induction or inhibition, we identified METTL16 as a novel ferroptotic repressor in HCC cells. The roles of METTL16 on ferroptosis and HCC development were investigated in multiple cell lines, human HCC organoids, subcutaneous xenografts and MYC/Trp53−/− HCC model in hepatocyte-specific Mettl16 knockout and overexpression mice. The underlying mechanism was elucidated with MeRIP/RIP-qPCR, luciferase assay, Co-IP assay and Mass Spectrometry. The clinical significance and relevance were evaluated in human samples. High METTL16 expression confers ferroptosis resistance in HCC cells and mouse models, and promotes cell viability and tumor progression. Mechanistically, METTL16 collaborates with IGF2BP2 to modulate SENP3 mRNA stability in an m6A-dependent manner, and the latter impedes the proteasome-mediated ubiquitination degradation of Lactotransferrin (LTF) via de-SUMOylation. Elevated LTF expression facilitates the chelation of free iron and reduces liable iron pool level. SENP3 and LTF are implicated in METTL16-mediated HCC progression and anti-ferroptotic effects both in vivo and in vitro. Clinically, METTL16 and SENP3 expression were positively correlated, and high METTL16 and SENP3 expression predicts poor prognosis in human HCC samples. Our study reveals a new METTL16-SENP3-LTF signaling axis regulating ferroptosis and driving HCC development. Targeting this axis is a promising strategy for sensitizing ferroptosis and against HCC.