Parabacteroides Johnsonii Inhibits the Onset and Progression of Colorectal Cancer by Modulating the Gut Microbiota

Colorectal cancer (CRC) is the third most prevalent malignant tumor and the second leading cause of cancer-related deaths globally. The genus Parabacteroides is an important component of the gut microbiota. P. distasonis and P. goldsteinii are reported probiotics, and their roles in CRC have been investigated in related studies. However, the association between P. johnsonii and CRC remains unknown. The purpose of the present study aimed to investigate the association of Parabacteroides johnsonii with colorectal cancer (CRC) symptom alleviation in azoxymethane (AOM)/dextran sulfate sodium (DSS)-treated C57BL/6 mice and to determine its underlying mechanisms. The results revealed that P. johnsonii intervention reduced the number and slowed the growth of colonic tumors, improved tumor histological scores, and decreased microenvironmental inflammation levels. P. johnsonii reversed dysbiosis in the gut microbiota of CRC mice, increased gut microbial species diversity, and maintained gut microbiota stability. Furthermore, P. johnsonii intervention increased the abundance of Bifidobacterium pseudolongum and Lactobacillus, which play a role in ameliorating AOM/DSS-induced gut microbiota dysbiosis. P. johnsonii intervention affected the metabolic pathways, including amino sugar degradation and galactose metabolism, sphingolipid synthesis, amino acid synthesis, and polyphenol synthesis pathways, with the tryptophan metabolism pathway as the primary pathway being affected.