Chinese herbal medicine Quxie formula inhibits colon cancer liver metastasis through modulating gut Actinobacteria induced apoptosis and anti-cancer immunity

Liver metastasis is the leading cause of mortality in colon cancer patients. Traditional Chinese herbal medicine Quxie formula (QX) has been shown to prolong survival, improve immune function and modulate the gut microbiome, particularly increasing Actinobacteria in metastatic colorectal cancer (mCRC) patients. However, the mechanism remains unclear. In Vitro , QX-containing serum was extracted from rats and used to culture three Actinobacteria strains: Bifidobacterium adolescentis (B. a.), Streptomyces carpaticus , and Bacillus . After screening for bacterial growth, QX- B. a. co-culture products were applied to HCT-116 cells to assess apoptosis and apoptosis-related protein expression. Caspase3, Caspase8, and Caspase9 pathways were blocked to further investigate apoptosis mechanisms. We then established a CT-26 liver metastasis mouse model pretreated with cocktail antibiotics, followed by 14-day QX decoction treatment. Liver tissue, immune function, cytokine, and gut microbiome were analyzed using Western blotting (WB), flow cytometry analysis, ELISA and 16S rRNA sequencing, respectively. In Vitro , QX-containing serum significantly promoted B. a. proliferation, and the QX- B. a. co-culture products induced higher apoptosis rates in HCT-116 cells than controls. WB results showed increased expression of Caspase3, Caspase8, Caspase9, Bax, and Bid, and decreased Bcl-2 expression in QX- B. a. co-culture groups. Blocking Caspase3, Caspase8, and Caspase9 significantly reduced apoptosis, confirming the Bcl-2/Bax pathway’s involvement. In Vivo , 10mg, 15mg, and 20mg daily QX treatment significantly reduced liver metastasis tumor burden. QX treatment increased gut Actinobacteria, Bacteroidet es, and Firmicutes abundance compared to model groups. QX significantly enhanced the protein expression of Caspase3, Caspase8 and Caspase9 in liver metastatic tissues. Compared to model group, QX could significantly enhance the proportion of CD8+, expression of TNF-α and IFN-γ in peripheral blood. In liver metastatic tissue, QX could restore the NK cells’ ability of targeting and killing cancer cells. Through UPLC-Q-TOF-MSE analysis, 69 molecular compounds were preliminarily identified in the decoction of QX and medicated serum. This study provides new insights into the gut microbiome-mediated anti-cancer effects of QX, warranting further investigation into its active components and therapeutic mechanism.