PO.MCB07.03 · 分子与细胞生物学
METTL1介导的缬氨酸tRNA m7G修饰驱动胰腺导管腺癌进展
METTL1-mediated m7G modification of valine tRNAs drives pancreatic ductal adenocarcinoma progression
作者与单位 Authors & Affiliations
摘要 Abstract
中文摘要
背景：转运RNA（tRNA）修饰在调控密码子特异性mRNA翻译和支持肿瘤细胞适应中发挥关键作用。RNA甲基转移酶METTL1在tRNA上安装N7-甲基鸟苷（m7G）修饰，塑造其密码子使用格局并影响蛋白质合成。然而，METTL1/tRNA轴在胰腺导管腺癌（PDAC）中的功能和机制仍知之甚少。本研究考察METTL1介导的m7G tRNA修饰在PDAC进展及其相关代谢重编程中的作用。
方法：利用来自癌症基因组图谱（TCGA）的转录组数据分析METTL1表达，并在一个独立的PDAC组织队列中通过qRT-PCR进行验证。通过CRISPR/Cas9生成METTL1敲除的PDAC细胞系。通过MTT、集落形成和划痕愈合实验评估细胞增殖和迁移，同时在异种移植模型中评估肿瘤生长。使用斑点印迹法测量整体tRNA m7G水平，并用qRT-PCR定量特定tRNA丰度。多聚核糖体谱分析识别METTL1依赖性翻译靶点，通过Seahorse线粒体压力测试评估线粒体功能。
结果：METTL1在PDAC中显著上调（p < 0.001），并与患者生存不良相关（p < 0.05）。METTL1敲除在体外和体内抑制了PDAC细胞增殖、迁移和肿瘤生长（p < 0.001）。机制上，METTL1缺失降低了m7G修饰缬氨酸tRNA的丰度，尤其是Val-AAC、Val-CAC和Val-TAC（均p < 0.001），导致富含缬氨酸密码子的氧化磷酸化基因翻译减少。因此，METTL1缺乏损害了线粒体呼吸和能量生成。一致地，缬氨酸tRNA表达在PDAC组织中升高（p < 0.01），选择性敲低这些tRNA通过破坏线粒体功能抑制了增殖和迁移（p < 0.001）。在METTL1缺陷细胞中重新导入Val-AAC、Val-CAC和Val-TAC恢复了生长（p < 0.001）和迁移能力（p < 0.01）。
结论：METTL1介导的缬氨酸tRNA m7G修饰通过重编程翻译格局以支持线粒体代谢，促进PDAC进展。这一METTL1-tRNA-线粒体轴代表了一个新的代谢脆弱点，也是胰腺癌中有前景的治疗靶点。
查看英文原文 English abstract
Background: Transfer RNA (tRNA) modifications play a critical role in regulating codon-specific mRNA translation and supporting tumor cell adaptation. The RNA methyltransferase METTL1 installs N7-methylguanosine (m7G) modifications on tRNAs, shaping their codon usage landscape and influencing protein synthesis. However, the function and mechanism of the METTL1/tRNA axis in pancreatic ductal adenocarcinoma (PDAC) remain poorly understood. This study examines the role of METTL1-mediated m7G tRNA modification in the progression of PDAC and its associated metabolic reprogramming.
Methods: METTL1 expression was analyzed using transcriptomic data from The Cancer Genome Atlas (TCGA) and validated in an independent PDAC tissue cohort by qRT-PCR. METTL1-knockout PDAC cell lines were generated via CRISPR/Cas9. Cellular proliferation and migration were assessed through MTT, colony formation, and wound-healing assays, while tumor growth was evaluated in xenograft models. Global tRNA m7G levels were measured using dot blot, and qRT-PCR was used to quantify specific tRNA abundances. Polysome profiling identified METTL1-dependent translational targets, and mitochondrial function was assessed by Seahorse Mito Stress testing.
Results: METTL1 was significantly upregulated in PDAC (p < 0.001) and correlated with poor patient survival (p < 0.05). METTL1 knockout suppressed PDAC cell proliferation, migration, and tumor growth (p < 0.001) in vitro and in vivo. Mechanistically, METTL1 loss decreased the abundance of m7G-modified valine tRNAs, particularly Val-AAC, Val-CAC, and Val-TAC (all p < 0.001), leading to reduced translation of valine codon-enriched oxidative phosphorylation genes. Consequently, METTL1 deficiency impaired mitochondrial respiration and energy production. Consistently, valine tRNA expression was elevated in PDAC tissues (p < 0.01), and selective knockdown of these tRNAs inhibited proliferation and migration (p < 0.001) by disrupting mitochondrial function. Reintroduction of Val-AAC, Val-CAC, and Val-TAC restored growth (p < 0.001) and migratory capacity (p < 0.01) in METTL1-deficient cells.
Conclusions: METTL1-mediated m7G modification of valine tRNAs promotes PDAC progression by reprogramming the translational landscape to support mitochondrial metabolism. This METTL1-tRNA-mitochondrial axis represents a novel metabolic vulnerability and a promising therapeutic target in pancreatic cancer.
利益披露 Disclosure
J. zhu, None..
Q. Zhang, None..
R. Su, None..
Q. Pan, None..
A. Goel, None.