Objective To investigate the preventive and therapeutic effects of Banxia Xiexin Decoction (半夏泻心汤, BXD) on colorectal cancer (CRC) and its underlying mechanism based on “farnesoid X receptor (FXR)-bile acid-immune microenvironment” axis. Methods A mouse CRC model was established by intraperitoneal injection of azoxymethane combined with oral administration of dextran sulfate sodium (DSS). Control group, model group, BXD low-, medium-, high-dose (3.915, 7.830, 15.660 g/kg) groups and mesalazine (0.6 g/kg) group were set up, with 10 mice in each group. Drugs were continuously given for eight weeks, general condition of mice was recorded. Histopathological changes in colon tissue were observed. Immunofluorescence staining was used to examine the distribution and expressions of CD11c, CD80 and CD86 in colon tissue. Flow cytometry was employed to detect the expressions of CD11b, CD11c, CD80, CD86 and CD206 in spleen tissue. Targeted metabolomics was used to analyze the levels of bile acids in feces of mice. Levels of interferon-γ (IFN-γ), interleukin-12 (IL-12), IL-18, total bile acids in serum and total bile acids in bile were detected. qRT-PCR was performed to measure the mRNA expressions of FXR, fibroblast growth factor 15 (FGF15), G protein-coupled receptor 41 (GPR41), GPR43, GPR109A, histone deacetylase 3 (HDAC3), HDAC7, inducible nitric oxide synthase (iNOS), IL-12, epidermal growth factor (EGF) and transforming growth factor-β1 (TGF-β1) in colon tissue. Western blotting was used to detect the protein expressions of FXR, iNOS, IL-12, EGF, TGF-β1, FGF15, GPR41, GPR43 and GPR109A in colon tissue. Results Compared with control group, the model group showed significant weight loss, increased number and size of colon tumors, severe disruption of glandular structure, irregular hyperplasia and distortion, formation of gland-like or nest-like structures, accompanied by marked inflammatory cell infiltration and tissue damage. PAS-positive substances were focally aggregated, distributed disorderly with irregular morphology. CD11c⁺ cells were extensively aggregated in colon tumor tissue, while CD80⁺ cells showed almost no fluorescence. The expressions of CD11b, CD11c and CD80 in spleen tissue was significantly increased (P < 0.01). Levels of deoxycholic acid (DCA), lithocholic acid (LCA) and taurocholic acid (TCA) in fecal were significantly elevated (P < 0.01). Protein expressions of iNOS, IL-12, EGF, TGF-β1, HDAC7 and HDAC3 in colon tissue were significantly increased (P < 0.01), while protein expressions of FXR, FGF15, GPR41, GPR43 and GPR109A were significantly decreased (P < 0.01). Compared with model group, the changes in the above indicators were reversed in both BXD and mesalazine groups, and the changes were more pronounced in BXD high-dose group (P < 0.05, 0.01). Conclusion BXD may exert its preventive and therapeutic effects on colorectal cancer by activating FXR signaling pathway, regulating bile acid metabolic homeostasis, and subsequently reshaping the tumor immune microenvironment.

Banxia Xiexin Decoction  /  colorectal cancer  /  farnesoid X receptor  /  immunity  /  tumor microenvironment  /  berberine  /  baicalin  /  glycyrrhizic acid  /  coptisine  /  palmatine