Identification of Molecular Targets of Bile Acids Acting on Colorectal Cancer and Their Correlation with Immunity

Background: Bile acids (BAs) are closely related to the occurrence and development of colorectal cancer (CRC), but the specific mechanism is still unclear. Aims: To identify potential targets related to BAs in CRC and analyze the correlation with immunity. Methods: The expression of BAs and CRC-related genes in TCGA was studied and screened using KEGG. GSE71187 was used for external validation of differentially expressed genes. Immunofluorescence, immunohistochemistry, and enzymatic cycling assays were used to detect the expression levels of the differentially expressed genes ki67 and BAs. Weighted gene coexpression network analysis (WGCNA) was used to identify genes associated with differential gene expression and immunity. The Cibersort algorithm was used to detect the infiltration of 22 kinds of immune cells in cancer tissues. The PPI network and ceRNA network were constructed to reveal the possible molecular mechanisms behind tumorigenesis. Results: The BA-related gene UGT2A3 is positively correlated with good prognoses in CRC. The expression level of UGT2A3 was negatively related to the BA level and positively related to the Ki67 proliferation index. The expression level of UGT2A3 was higher in the moderately differentiation and advanced stage (stage IV) of CRC. In addition, the expression level of UGT2A3 is correlated with CD8+ T cells. A PPI network related to UGT2A3 and T-cell immune-related genes was constructed. A ceRNA network containing 32 miRNA‒mRNA and 40 miRNA‒lncRNA regulatory pairs was constructed. Conclusion: UGT2A3 is a potential molecular target of bile acids in the regulation of CRC and is related to T-cell immunity.