Colorectal cancer, one of the most common cancers in the world, has relatively good five-year survival rates for earlier stages. At later stages, however, survival goes down and the risk of cancer recurrence goes up considerably.
To help address this problem, a team of researchers at the National University of Singapore Yong Loo Lin School of Medicine have found a way to turn a cocktail of bacteria and vegetables into a targeted system that seeks out and kills colorectal cancer cells.
The study, conducted in the lab of Associate Professor Matthew Chang and led by Dr. Chun-Loong Ho, used genetic techniques to engineer a form of E. coli Nissle, a harmless gut bacteria. The process transformed the bacteria into a probiotic that attaches to the surface of colorectal cancer cells.
The mixture of engineered probiotics and a broccoli extract, or water containing the dietary substance, killed more than 95 percent of colorectal cancer cells in a dish and reduced tumor numbers in mice with colorectal cancer by 75 percent.
Normal cells are not affected by the mixture, nor are the cells of other types of cancer, such as breast and stomach cancer.
Dr. Ho and Associate Professor Chang, along with colorectal cancer specialist Dr. Yong Wei Peng at the National University Hospital, envision that these probiotics could be used in two ways: 1) as prevention, and 2) to clean up the cancer cells remaining after surgical removal of tumors. One day, patients may be able to take the probiotics as a dietary supplement along with their broccoli to prevent colorectal cancer or to reduce recurrence after cancer surgery.
This effort illustrates the concept of food as medicine. As Associate Professor Chang puts it, "One exciting aspect of our strategy is that it just capitalizes on our lifestyle, potentially transforming our normal diet into a sustainable, low-cost therapeutic regimen. We hope that our strategy can be a useful complement to current cancer therapies."
Or, even more simply, in Dr. Ho's words, "Mothers are right after all, eating vegetables is important."
The study is available online and in the current issue of Nature Biomedical Engineering.