Gut microbes possibly influence not only the development of many human diseases, but also how these diseases respond to treatment. In tumor models, for example, gut microbes can modulate the efficacy and toxicity of chemotherapeutic drugs through their effects on drug metabolism or on the immune system. Yu et al. report that gut microbes can alter tumor chemosensitivity by rewiring tumor-cell signaling. In cell and mouse models of colorectal cancer, the Fusobacterium nucleatum promotes tumor resistance to 5-fluorouracil and oxaliplatin. The bacterium causes tumor cells to switch signaling from apoptosis to autophagy, thereby allowing them to escape the drugs’ cytotoxic effects. The clinical significance of this intriguing mechanism remains to be studied.
