Metagenomic Analysis of Intratumoral Microbiome Linking to Response to Neoadjuvant Chemoradiotherapy in Rectal Cancer

Causal roles of gut microbiota in cholangiocarcinoma etiology suggested by genetic study

BACKGROUND

Cholangiocarcinoma (CCA) is a highly malignant biliary tract cancer with poor prognosis. Previous studies have implicated the gut microbiota in CCA, but evidence for causal mechanisms is lacking.

AIM

To investigate the causal relationship between gut microbiota and CCA risk.

METHODS

We performed a two-sample mendelian randomization study to evaluate potential causal associations between gut microbiota and CCA risk using genome-wide association study summary statistics for 196 gut microbial taxa and CCA. Genetic variants were used as instrumental variables. Multiple sensitivity analyses assessed result robustness.

RESULTS

Fifteen gut microbial taxa showed significant causal associations with CCA risk. Higher genetically predicted abundance of genus Eubacteriumnodatum group, genus Ruminococcustorques group, genus Coprococcus, genus Dorea, and phylum Actinobacteria were associated with reduced risk of gallbladder cancer and extrahepatic CCA. Increased intrahepatic CCA risk was associated with higher abundance of family Veillonellaceae, genus Alistipes, order Enterobacteriales, and phylum Firmicutes. Protective effects against CCA were suggested for genus Collinsella, genus Eisenbergiella, genus Anaerostipes, genus Paraprevotella, genus Parasutterella, and phylum Verrucomicrobia. Sensitivity analyses indicated these findings were reliable without pleiotropy.

CONCLUSION

This pioneering study provides novel evidence that specific gut microbiota may play causal roles in CCA risk. Further experimental validation of these candidate microbes is warranted to consolidate causality and mechanisms.

Integrated gut microbiome and metabolome analysis reveals the inhibition effect of Lactobacillus plantarum CBT against colorectal cancer

The microecological stability of the gut microbiota plays a pivotal role in both preventing and treating colorectal cancer (CRC). This study investigated whether Lactobacillus plantarum CBT (LP-CBT) prevents CRC by inducing alterations in the gut microbiota composition and associated metabolites. The results showed that LP-CBT inhibited colorectal tumorigenesis in azoxymethane/dextran sulfate sodium (AOM/DSS)-treated mice by repairing the intestinal barrier function. Furthermore, LP-CBT decreased pro-inflammatory cytokines and anti-inflammatory cytokines. Importantly, LP-CBT remodeled intestinal homeostasis by increasing probiotics (Coprococcus, Mucispirillum, and Lactobacillus) and reducing harmful bacteria (Dorea, Shigella, Alistipes, Paraprevotella, Bacteroides, Sutterella, Turicibacter, Bifidobacterium, Clostridium, Allobaculum), significantly influencing arginine biosynthesis. Therefore, LP-CBT treatment regulated invertases and metabolites associated with the arginine pathway (carbamoyl phosphate, carboxymethyl proline, L-lysine, 10,11-epoxy-3-geranylgeranylindole, n-(6)-[(indol-3-yl)acetyl]-L-lysine, citrulline, N2-succinyl-L-ornithine, and (5-L-glutamyl)-L-glutamate). Furthermore, the inhibitory effect of LP-CBT on colorectal cancer was further confirmed using the MC38 subcutaneous tumor model. Collectively, these findings offer compelling evidence supporting the potential of LP-CBT as a viable preventive strategy against CRC.