Integrative analysis of pancreatic microbiota and metabolome in patients with pancreatic ductal adenocarcinoma.

The importance of microbiota-associated metabolites in pancreatic ductal adenocarcinoma (PDAC) tumorigenesis highlights the need to investigate the microbiota and metabolome along the normal-adjacent-carcinoma sequence to explore their mechanistic implications in PDAC tumorigenesis. We characterized the pancreatic microbiota and metabolome in four distinct tissue groups using 16S rRNA amplicon sequencing and untargeted metabolomics: tumor tissues from 23 PDAC patients (PDAC T), their matched para-carcinoma tissues (PCT), tumor tissues from 13 pancreatic benign tumor patients (Control T), and their matched non-tumor tissues (Control N). For the selected metabolites, we verified their functional activities using cell proliferation assay. From Control N, through PCT, to PDAC T, there were 90 significantly differential genera, of which seven genera increased and 65 genera decreased sequentially. Specifically, Peptostreptococcus, norank_f__Mitochondria, and Ileibacterium increased, while Faecalibacterium, Ruminococcus, Subdoligranulum, and Coprococcus decreased sequentially. Among altered metabolites, beta-guanidinopropionic acid (GPA), S-(2-Carboxyethyl)-L-cysteine, L-lactic acid, and 3-hydroxybutanoic acid increased, while (3Z)-2-Propylpent-3-enoic acid, linoleic acid, and monopalmitin decreased sequentially. PDAC-associated metabolites were enriched in the GABAergic synapse, butanoate metabolism, purine metabolism, and CCM in cancer pathways. GPA and S-(2-Carboxyethyl)-L-cysteine were also enriched in the chemotherapy-resistant patients compared with chemotherapy-sensitive patients, while Faecalibacterium and (3Z)-2-Propylpent-3-enoic acid were also reduced. In both PDAC tumorigenesis and chemotherapy-resistant patients, decreased Faecalibacterium was positively correlated with (3Z)-2-Propylpent-3-enoic acid, but negatively correlated with GPA and S-(2-carboxyethyl)-L-cysteine. CCK8 assays confirmed that GPA and S-(2-carboxyethyl)-L-cysteine promoted the proliferation of PDAC cell lines. GPA and S-(2-Carboxyethyl)-L-cysteine were enriched in both PDAC tumorigenesis and chemotherapy-resistant patients, while Faecalibacterium and (3Z)-2-Propylpent-3-enoic acid were reduced. GPA and S-(2-carboxyethyl)-L-cysteine could promote the proliferation of PDAC cell lines.