In a breakthrough study, scientists have uncovered a surprising ally in the fight against cancer: the bacteria living within tumors. According to World Pharma News, an international team led by researchers from the MRC Laboratory of Medical Sciences at Imperial College London and the University of Cologne has found that certain microbes associated with tumors can produce a molecule that slows cancer growth and enhances the effectiveness of chemotherapy.
Most are familiar with the bacteria that inhabit our skin and digestive tract, but recent research shows that tumors themselves host unique microbial communities. Until now, little was known about how these tumor-dwelling bacteria influence cancer progression or therapy outcomes.
Published in Cell Systems on September 10, 2025, the new study marks a significant leap forward. The team used advanced screening techniques on more than 1,100 experimental conditions using a microscopic worm called C. elegans. They discovered that the common gut bacterium E. coli produces a compound called 2-methylisocitrate (2-MiCit), which can make the chemotherapy drug 5-fluorouracil (5-FU) substantially more effective.
Further computer modelling revealed that tumor microbiomes from human colorectal cancer patients can also generate 2-MiCit. Testing the compound in both human cancer cells and a fly model of colorectal cancer showed that 2-MiCit not only suppressed cancer growth but, in the fly model, also prolonged survival.
The secret lies in how 2-MiCit operates at the molecular level. The study revealed that this bacterial molecule targets a crucial enzyme within the mitochondria (the cell’s energy hub) of cancer cells. This interference leads to DNA damage and activates anti-cancer pathways, weakening cancer cells and making them more susceptible to chemotherapy. The combined treatment of 2-MiCit and 5-FU proved far more effective at destroying cancer cells than either agent alone.
Recognizing the potential for therapy, the researchers collaborated with medicinal chemists to synthesize a more potent version of 2-MiCit. This modified compound was even better at killing cancer cells, suggesting new avenues for drug development inspired by natural microbial products.
Professor Filipe Cabreiro, lead scientist on the project, highlights the broader significance: “We’re beginning to unravel the chemical dialogue between bacteria and cancer cells. Harnessing this conversation gives us new tools to boost current treatments and develop smarter therapies.”
First author Dr. Daniel Martinez-Martinez emphasizes the complexity and promise of this approach: “That a single molecule from bacteria can have such a profound impact on cancer progression is remarkable. It underscores the importance of considering the whole biological ecosystem in cancer care.”
These discoveries point to an exciting future where the microbiome inside tumors could be leveraged for more effective and personalized cancer treatments. By targeting both the tumor and its microbial partners, researchers may unlock entirely new strategies to combat cancer.
This pioneering work was supported by the Leverhulme Trust, Wellcome Trust/Royal Society, the German Research Foundation, and the Medical Research Council.
