AARS1‐Mediated H3K27 Lactylation Rewires Glycolysis to Sustain Aggressive and Recurrent Bladder Cancer

Recurrence and progression remain major clinical challenges in bladder cancer (BC), yet the mechanisms linking glycolysis to persistent malignant states remain incompletely defined. Here, we identify alanyl tRNA synthetase 1 (AARS1) as a clinically relevant driver of aggressive and recurrent BC. AARS1 is upregulated in BC tissues, enriched in muscle invasive and recurrent tumors, and associated with unfavorable survival. Functionally, AARS1 promotes proliferation, epithelial mesenchymal transition, invasion, apoptosis resistance, tumor growth, and lung colonization. Mechanistically, AARS1 enhances phosphoinositide 3 kinase (PI3K) pathway output, glycolytic flux, and lactate production. Increased lactate availability is linked to histone H3 lysine 27 lactylation (H3K27la) enrichment at the hexokinase 2 (HK2) promoter, increased chromatin accessibility, and HK2 transcriptional activation, supporting an HK2 centered metabolic and epigenetic reinforcement program. HK2 perturbation attenuates AARS1 associated glycolytic and malignant phenotypes. Through structure guided screening and surface plasmon resonance validation, we further identified eltrombopag as an AARS1 binding compound that pharmacologically suppressed the AARS1 associated PI3K, glycolysis, lactate, H3K27la, and HK2 program and restrained tumor progression in preclinical models. These findings define an AARS1 associated metabolic and epigenetic program in BC and nominate AARS1 targeting strategies as a direction for further therapeutic development.