# Scientists Identify Bacterial Receptor Triggering Colon Cancer Researchers discover how gut bacteria toxins attach to cells, enabling potential new preventative therapies. - **Source:** [Latest Science News -- ScienceDaily](https://brifing.si/source/0eef8637-6c5b-4e79-8f5b-6c9c6b36cf16) - **Published:** 2026-10-31 - **Original article:** - **On Brifing:** https://brifing.si/s/8cb95d5b-9f2d-4e7d-a780-6cf7dc0a865c ## Unlocking the Bacterial Mystery For two decades, the link between Bacteroides fragilis toxin and colon tumor formation remained partially understood. While scientists knew the toxin damaged the colon, the initial attachment mechanism was unknown. Researchers at Johns Hopkins have now identified claudin-4 as the essential docking point, finally revealing how the toxin begins its attack. ## CRISPR-Led Discovery Process To identify the receptor, researchers utilized CRISPR gene-editing technology to systematically disable genes in colon epithelial cells. This genome-wide screening effort, conducted in collaboration with Harvard Medical School, pinpointed the gene responsible for claudin-4. When this specific gene was deactivated, the BFT toxin could no longer bind to the colon cells. ## Claudin-4 as a Receptor The identification of claudin-4 surprised researchers who expected the toxin to interact with traditional signaling proteins. Instead, the toxin targets a protein responsible for maintaining tight junctions between cells. This discovery highlights a unique mechanism where a protease-class toxin requires a physical docking point before it can effectively damage the E-cadherin barrier. ## Validating the Molecular Complex Structural biologists at the Molecular Biology Institute of Barcelona confirmed the binding mechanism through advanced laboratory interaction measurements. The study demonstrated that each BFT molecule pairs with one claudin-4 receptor molecule. This physical evidence provides a clear, validated model of how the toxin anchors itself to the intestinal lining before causing inflammation. ## Developing a Molecular Decoy Leveraging this discovery, the team engineered a soluble protein decoy containing claudin-4 sequences. In mouse models, this decoy successfully intercepted the BFT toxin before it could reach the actual colon cells. By effectively luring the toxin away from its target, the strategy prevented the harmful tissue damage typically associated with the bacterial infection. ## Future Therapeutic Implications The research team is now exploring small molecules and biologics to refine this decoy strategy for potential human application. While current results are promising, future iterations must improve pharmacological properties for clinical use. This approach shifts the focus from repairing cellular damage to blocking the initial infection step, potentially preventing associated disease progression. ## Structural Challenges Remain Despite the breakthrough, the precise three-dimensional structure of the BFT-claudin-4 interaction remains elusive. Even advanced artificial intelligence tools like AlphaFold have not yet fully resolved the complex interface. Mapping this structure is a critical next step for designing highly effective compounds that can reliably prevent the toxin from binding to human cells. ## Broader Clinical Significance This discovery resolves a major scientific question regarding colorectal cancer development that has persisted since 2009. Beyond cancer, the findings offer new pathways for detecting and treating conditions linked to bacterial toxins, including diarrhea and bloodstream infections. The work underscores the value of identifying specific molecular targets to interrupt harmful biological processes early. ## Sources covering this story - https://www.sciencedaily.com/releases/2026/10/261031012912.htm — --- _Summary written by Brifing from the original reporting. Copyright in the original article belongs to its publisher; read the full piece at the link above._