Department of Gastrointestinal Surgery, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China.
National-Local Joint Engineering Laboratory of Druggability and New Drug Evaluation, National Engineering Research Center for New Drug and Druggability (cultivation), Guangdong Province Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, China.
EMBO J. 2020 Jun 17;39(12):e103181. doi: 10.15252/embj.2019103181. Epub 2020 May 5.
N6-methyladenosine (m A) is an abundant nucleotide modification in mRNA, known to regulate mRNA stability, splicing, and translation, but it is unclear whether it is also has a physiological role in the intratumoral microenvironment and cancer drug resistance. Here, we find that METTL3, a primary m A methyltransferase, is significantly down-regulated in human sorafenib-resistant hepatocellular carcinoma (HCC). Depletion of METTL3 under hypoxia promotes sorafenib resistance and expression of angiogenesis genes in cultured HCC cells and activates autophagy-associated pathways. Mechanistically, we have identified FOXO3 as a key downstream target of METTL3, with m A modification of the FOXO3 mRNA 3'-untranslated region increasing its stability through a YTHDF1-dependent mechanism. Analysis of clinical samples furthermore showed that METTL3 and FOXO3 levels are tightly correlated in HCC patients. In mouse xenograft models, METTL3 depletion significantly enhances sorafenib resistance of HCC by abolishing the identified METTL3-mediated FOXO3 mRNA stabilization, and overexpression of FOXO3 restores m A-dependent sorafenib sensitivity. Collectively, our work reveals a critical function for METTL3-mediated m A modification in the hypoxic tumor microenvironment and identifies FOXO3 as an important target of m A modification in the resistance of HCC to sorafenib therapy.
N6-甲基腺苷(m A)是 mRNA 中一种丰富的核苷酸修饰,已知其可调节 mRNA 的稳定性、剪接和翻译,但它是否在肿瘤内微环境和癌症药物耐药性中也具有生理作用尚不清楚。在这里,我们发现 METTL3,一种主要的 m A 甲基转移酶,在人索拉非尼耐药性肝癌(HCC)中显著下调。在低氧条件下耗尽 METTL3 会促进培养的 HCC 细胞中的索拉非尼耐药性和血管生成基因的表达,并激活自噬相关途径。在机制上,我们已经确定 FOXO3 是 METTL3 的关键下游靶标,METTL3 通过 YTHDF1 依赖性机制修饰 FOXO3 mRNA 3'非翻译区,增加其稳定性。对临床样本的分析进一步表明,METTL3 和 FOXO3 水平在 HCC 患者中紧密相关。在小鼠异种移植模型中,通过消除鉴定的 METTL3 介导的 FOXO3 mRNA 稳定化,耗尽 METTL3 会显著增强 HCC 对索拉非尼的耐药性,而过表达 FOXO3 则恢复 m A 依赖性索拉非尼敏感性。总之,我们的工作揭示了 METTL3 介导的 m A 修饰在缺氧肿瘤微环境中的关键功能,并确定 FOXO3 是 HCC 对索拉非尼治疗耐药性中 m A 修饰的重要靶标。