CD26 (dipeptidyl peptidase-4) is a marker of colorectal cancer stem cells with high metastatic potential and resistance to therapy. Although CD26 expression is known to be associated with tumor progression, its functional involvement in epithelial-mesenchymal transition (EMT) and metastasis remains to be fully elucidated. In this study, we aimed to investigate the effects of a monoclonal anti-CD26 antibody on EMT-related phenotypes and metastatic behavior in colorectal cancer cells. We evaluated changes in EMT markers by quantitative PCR and Western blotting, assessed cell motility and invasion using scratch wound-healing and Transwell assays, and examined metastatic potential in vivo using a splenic injection mouse model. Treatment with the anti-CD26 antibody significantly increased the expression of the epithelial marker E-cadherin and reduced levels of EMT-inducing transcription factors, including ZEB1, Twist1, and Snail1, at the mRNA and protein levels. Functional assays revealed that the antibody markedly inhibited cell migration and invasion in vitro without exerting cytotoxic effects. Furthermore, systemic administration of the anti-CD26 antibody significantly suppressed the formation of liver metastases in vivo. These findings suggest that CD26 may contribute to the regulation of EMT and metastatic behavior in colorectal cancer. Our data highlight the potential therapeutic utility of CD26-targeted antibody therapy for suppressing EMT-associated phenotypes and metastatic progression.

Postbiotics produced by beneficial bacteria are emerging as safe dietary approaches to intestinal inflammation. We evaluated intestinal bacterial metabolites (IBM), a cell-free fermented soybean extract generated by co-culturing 31 Lactobacillus/Bifidobacterium-related strains, for prophylactic protection in 3% dextran sulfate sodium (DSS)-induced colitis. Male C57BL/6NJ mice received oral IBM (0.4 or 2 mL/kg/day) or vehicle for 7 days before and during 7 days of DSS. Disease activity index (DAI), colon length, and histopathology were assessed, and endpoint serum cytokines were quantified by a multiplex bead assay. DSS-independent responses were examined in healthy mice after 7 days of IBM by rectal RNA sequencing and cecal 16S rDNA profiling, and direct epithelial effects were tested in HCT-116 and DLD-1 cells treated with 2% IBM. IBM attenuated colitis, improving DAI, preventing colon shortening, and ameliorating histopathology, with decreased IL-23 and IL-17A and increased IFN-β and GM-CSF. Rectal transcriptomics showed modulation of circadian programs, upregulation of mucosal/barrier genes, and reduced extracellular-matrix remodeling signatures. IBM increased junctional proteins and barrier-related transcripts in vitro and shifted the microbiota, increasing Lactobacillus and Roseburia while decreasing Streptococcus and Staphylococcus. These coordinated clinical, immunological, transcriptomic, epithelial, and microbiome changes support prophylactic protection by IBM against DSS colitis.