Targeting the gut-tumor axis: probiotic therapy as an adjunct strategy in colorectal cancer treatment

Colorectal cancer (CRC) is a multifactorial disease driven by interactions among host genetics, immune dysregulation, environmental factors, and gut microbiota. The gut-tumor axis regulates CRC progression through inflammatory signaling, oxidative stress, epithelial barrier disruption, and immune imbalance. Probiotic-derived metabolites act as bioactive molecules capable of restoring host-microbiome homeostasis and modulating tumor-associated pathways.

To evaluate probiotic metabolites as adjunct therapeutic agents in CRC using integrative multi-omics analysis and in vitro validation.

A systems biology approach integrating network pharmacology, transcriptomics, proteomics, metabolomics, and microbiome profiling was applied. Twelve probiotic metabolites yielded 428 predicted targets, with 162 overlapping CRC-associated genes. CRC cell lines (HCT116, HT-29, Caco-2, SW480) were treated and analyzed for viability, apoptosis, gene/protein expression, cytokines, metabolites, and microbial composition.

Sodium butyrate (5 mM) reduced cell viability by 35.5-42.3% (p < 0.001) and increased apoptosis from 8.6% to 32.4%, reaching 41.2% when combined with indole-3-acetic acid (IAA, 100 μM), suggesting a synergistic pro-apoptotic effect. RNA-seq identified 1,248 DEGs, with upregulation of BAX and CASP3 (log₂FC +1.8 to +2.3) and downregulation of IL6, TNF, and NFKB1 (-1.5 to -2.1). Proteomics revealed 412 differentially expressed proteins, including downregulation of AKT1 (-1.6-fold), MAPK1 (-1.4-fold), and EGFR (-1.3-fold), and upregulation of CASP3 (+1.7-fold) and BAX (+1.5-fold). Cytokines IL-6, TNF-α, and IL-1β decreased by 48.2%, 44.7%, and 39.5%, respectively, while IL-10 increased by 26.3%. Metabolomics showed a 2.8-fold increase in butyrate and ~35% reduction in oxidative stress. Microbiome diversity improved (Shannon index 2.8-3.6).

Probiotic-derived metabolites modulate NF-κB, PI3K-Akt, MAPK, and apoptosis pathways, supporting their potential role as adjunct therapeutic agents in CRC management.