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. Citation Format: jiabei zhu, Qi Zhang, Rui Su, Qiuhui Pan, Ajay Goel. METTL1-mediated m7G modification of valine tRNAs drives pancreatic ductal adenocarcinoma progression abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 5962.
Zhu et al. (Fri,) studied this question.