Microbiome Modulation with Lactobacillus rhamnosus GG Potentiates Curcumin's Efficacy in Reversing Gemcitabine Resistance of Gallbladder Cancer through Gut Microbiota-PI3K/AKT Axis.

Gemcitabine (GEM) resistance remains a major challenge in the treatment of gallbladder cancer (GBC). This study investigated the synergistic effect of curcumin (CUR) combined with the probiotic Lactobacillus rhamnosus GG (LGG) in reversing chemoresistance through modulation of the gut microbiota. In GEM-resistant GBC-SD cells, the CUR-LGG combination significantly inhibited cell proliferation, suppressed migration and invasion, and induced apoptosis, as demonstrated by CCK-8, wound healing, Transwell, and flow cytometry assays. Western blot analysis revealed corresponding regulation of proliferation markers (Ki67, PCNA), apoptosis-related proteins (Bcl-2, Bax, cleaved Caspase-3), and epithelial-mesenchymal transition markers. In xenograft models, the combined treatment markedly suppressed tumor growth and altered gut microbial composition, increasing beneficial bacteria (Lactobacillus, Bifidobacterium) while reducing pathogenic taxa. LC-MS analysis further demonstrated restoration of bile acid homeostasis, characterized by elevated primary bile acids (GCA, CDCA) and decreased secondary bile acids (DCA, LCA). Mechanistically, the intervention significantly inhibited PI3K/AKT signaling, as confirmed by Western blot and immunohistochemistry. Bioinformatic analysis further identified PI3K/AKT as a central regulatory pathway. These findings indicate that probiotic-assisted CUR therapy reverses GEM resistance by remodeling the gut microbiota and its metabolic outputs, thereby suppressing oncogenic signaling pathways. This strategy provides a promising microbiota-based approach for improving therapeutic outcomes in GBC.