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.

中文翻译：

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METTL16-SENP3-LTF轴赋予肝细胞癌抗铁死亡性并促进肿瘤发生


铁死亡以铁依赖性脂质过氧化为特征，由于其肿瘤易感性，成为肝细胞癌（HCC）干预的有前途的途径。 RNA N6-甲基腺苷 (m6A) 修饰参与了多种类型的受调节细胞死亡。然而，m6A相关调节因子在HCC细胞铁死亡中的作用和分子机制仍不清楚。通过检查一系列 m6A 修饰酶对铁死亡诱导或抑制的影响，我们确定 METTL16 是 HCC 细胞中一种新型的铁死亡抑制剂。在多种细胞系、人类 HCC 类器官、皮下异种移植物以及肝细胞特异性 Mettl16 敲除和过表达小鼠的 MYC/Trp53−/− HCC 模型中研究了 METTL16 对铁死亡和 HCC 发展的作用。通过 MeRIP/RIP-qPCR、荧光素酶测定、Co-IP 测定和质谱分析阐明了潜在的机制。在人类样本中评估了临床意义和相关性。 METTL16 高表达赋予 HCC 细胞和小鼠模型铁死亡抵抗力，并促进细胞活力和肿瘤进展。从机制上讲，METTL16 与 IGF2BP2 合作，以 m6A 依赖性方式调节 SENP3 mRNA 稳定性，后者通过去 SUMO 化阻止蛋白酶体介导的乳转铁蛋白 (LTF) 泛素化降解。 LTF 表达升高有利于游离铁的螯合并降低易受影响的铁池水平。 SENP3 和 LTF 与 METTL16 介导的 HCC 进展以及体内和体外抗铁死亡作用有关。临床上，METTL16和SENP3表达呈正相关，METTL16和SENP3高表达预示人类HCC样本预后不良。 我们的研究揭示了一个新的 METTL16-SENP3-LTF 信号轴调节铁死亡并驱动 HCC 的发展。针对该轴是一种有前途的策略，可以使铁死亡变得敏感并对抗肝癌。