The lactate-GPR81-AMIGO2 axis promotes pancreatic ductal adenocarcinoma progression and predicts poor prognosis

Pancreatic ductal adenocarcinoma (PDAC) carries an extremely poor prognosis. Excessive lactate accumulation occurs in the hypoxic tumor microenvironment, yet the roles of lactate receptor GPR81 and adhesion molecule AMIGO2 and their crosstalk in PDAC remain unclear. This study applied PDAC data from TCGA/GTEx databases, 83 clinical samples from Zhongda Hospital, CFPAC1/CAPAN2/CAPAN1 cell lines, and BALB/c-nu nude mouse models. Lactate levels were detected; Expression of GPR81, AMIGO2 and related molecules were measured by qPCR, IHC and Western Blot. GPR81/AMIGO2 were regulated via lentivirus, siRNA or plasmid transfection. Cell functions and tumorigenesis were evaluated by CCK-8, wound-healing, Transwell and in vivo assays. RNA-seq and enrichment analyses screened differential genes; Cox regression and nomogram assessed the prognostic value of AMIGO2. Lactate concentration and GPR81 expression were significantly increased in PDAC and correlated with poor prognosis. High-lactate conditions upregulated GPR81 expression under both energy deficiency and normal energy supply conditions. GPR81 knockdown inhibited PDAC cell proliferation, migration and tumorigenicity, whereas overexpression showed the opposite effects independently of lactylation. GPR81 activated the TGFβ2-pSMAD2/3-ZEB1 pathway by upregulating AMIGO2, and AMIGO2 rescued the inhibitory effects caused by GPR81 knockdown. AMIGO2 was highly expressed in PDAC and acted as an independent prognostic factor. The prognostic model combining AMIGO2 and TNM staging system showed superior predictive accuracy. Our results elucidate that AMIGO2 mediates lactate-GPR81-driven PDAC progression through the TGFβ2-pSMAD2/3-ZEB1 signaling cascade. AMIGO2 is an independent prognostic factor for PDAC, and its integration with the TNM staging system yields a preliminary prognostic model with improved predictive performance in our single-center cohort.