Obesity-driven microbial GABA depletion promotes metabolic rewiring and colorectal cancer progression

Obesity is a major risk factor for colorectal cancer (CRC), yet the mechanisms linking obesity-associated gut dysbiosis to tumor progression remain unclear. Here, we show that a high-fat diet and fecal microbiota from patients with obesity-associated CRC deplete the GABA-producing commensal Bacteroides ovatus, resulting in reduced luminal GABA and accelerated tumorigenesis. Microbial GABA activates epithelial GABAB receptor signaling and induces TPI1 through the PI3K-HIF1α pathway. Increased TPI1-derived glyceraldehyde-3-phosphate inhibits PPP1CA, maintains YAP phosphorylation, restricts nuclear YAP activity, and suppresses pentose phosphate pathway flux, thereby limiting tumor growth. Consistently, obesity-associated CRC exhibits reduced fecal GABA, decreased TPI1 expression, and metabolic rewiring. A GABA-deficient B. ovatus mutant fails to restore GABA or suppress tumors despite normal colonization, whereas oral GABA supplementation or recolonization with wild-type B. ovatus markedly reduces tumor burden. These findings identify a microbiota-neurotransmitter-metabolism axis linking obesity to CRC and suggest microbiota-based GABA restoration as a potential preventive strategy.