METTL1-Mediated m7G Modification of Valine tRNAs Drives Metabolic Adaptation in Pancreatic Ductal Adenocarcinoma

Transfer RNA (tRNA) modifications play a critical role in regulating codon-specific mRNA translation and enabling tumor cell adaptation. The RNA methyltransferase METTL1 installs N7-methylguanosine (m⁷G) modifications on tRNAs, thereby shaping codon usage and translational output. However, the function and mechanistic contribution of the METTL1–tRNA axis in pancreatic ductal adenocarcinoma (PDAC) remain poorly defined. Here, we show that METTL1 is overexpressed in PDAC tissues and that elevated METTL1 expression is associated with poor patient survival. Genetic ablation of METTL1 markedly suppresses PDAC cell proliferation, migration, and tumor growth in vitro and in vivo. Mechanistically, METTL1 loss selectively reduces m⁷G-modified valine tRNAs – particularly, Val-AAC, Val-CAC, and Val-TAC – leading to impaired translation of valine-enriched oxidative phosphorylation transcripts. As a consequence, METTL1 deficiency disrupts mitochondrial respiration and energy production in PDAC cells. Consistent with this model, valine tRNA levels are elevated in PDAC tissues, and their selective depletion phenocopies METTL1 loss by impairing mitochondrial bioenergetics and tumor cell fitness. Thus, the METTL1–valine tRNA axis promotes PDAC progression through codon-dependent translational control of mitochondrial complex I and oxidative metabolism. Together, our findings identify a METTL1–tRNA–mitochondrial signaling axis as a previously unrecognized metabolic vulnerability and a promising therapeutic target in pancreatic cancer.