Abstract
Gastrointestinal (GI) cancers exhibit aberrant lipid metabolism, yet the causal mechanisms remain elusive. Here, we integrated Mendelian randomization (MR) and multi-omics data to dissect metabolic drivers of 20 GI diseases. Focusing on colorectal (CC) and esophageal cancer (EC), we identified five metabolites (e.g., 1,2-di-palmitoyl-sn-glycero-3-phosphocholine) and arachidonic acid ethyl ester as causal drivers. Summary-data-based MR and colocalization analysis (PP.H4 > 0.75) revealed FADS1 as a master regulator of these metabolites, with genetic variants exhibiting tissue-specific lipidomic effects. Functional validation using FADS1-knockout cell lines and mouse models demonstrated that FADS1 inhibition suppresses tumor cell proliferation, migration, and invasion while promoting apoptosis. In vivo, FADS1 deletion reduced chemically induced CC/EC tumor burden by 62-75%, accompanied by decreased Ki-67/MMP-9 expression and inflammatory infiltration. Mechanistically, FADS1 ablation disrupted lipid metabolism (reduced linoleic acid and arachidonic acid) and attenuated PI3K/AKT and MAPK signaling. Multi-omics integration further corroborated FADS1-mediated epigenetic regulation (e.g., mQTL-driven DNA methylation). This study establishes FADS1 as a pivotal orchestrator of GI carcinogenesis via metabolic reprogramming and signaling dysregulation, offering a compelling therapeutic target for precision oncology in CC and EC. Regulatory mechanisms of FADS1 in CC and EC.