Colorectal cancer: a growing threat, especially for younger adults. As of 2024, it's the third leading cause of cancer-related deaths in men and the fourth in women in the U.S. But here's where it gets concerning: rates are climbing among young adults, increasing by approximately 2.4% each year from 2012 to 2021. One major culprit? Our modern diets.
Researchers have found a direct link between high-fat diets and an increased risk of colorectal cancer (CRC). A recent study, published in the Journal of Biological Chemistry, sheds light on how this happens. The research, led by Lopa Mishra and Krishanu Bhowmick at the Feinstein Institutes for Medical Research, investigated the role of gut microbes in this process.
The study revealed that a high-fat diet in mice boosts ammonia-producing bacteria in the gut microbiome, which, in turn, fuels CRC development. This effect is mediated by the transforming growth factor beta (TGF-β) signaling pathway. But how does this pathway contribute to cancer?
In the early stages of cancer, TGF-β signaling typically acts as a tumor suppressor. However, it can promote tumor growth later on. Mishra's team previously demonstrated that disrupting TGF-β signaling caused mice to develop CRC and other gastrointestinal cancers. The microbiome plays a crucial role here: studies show that TGF-β deficiency doesn't trigger tumors in mice without a microbiome. Furthermore, microbiome-induced increases in ammonia levels can promote CRC. Mishra explained that the ammonia produced by the gut microbiome likely helps tumors outcompete healthy tissue because normal cells can't tolerate high ammonia levels.
And this is the part most people miss: the researchers discovered that ammonia interacts with a specific component of the TGF-β pathway called βII-spectrin (SPTBN1). Normally, SPTBN1 helps promote tumor suppression. However, ammonia disrupts this interaction, essentially disabling the tumor-suppressing function. When the researchers inhibited SPTBN1, the tumor suppression functions were restored.
Mice on a high-fat diet, similar to a fast-food-heavy human diet, experienced significant microbiome changes, including increased levels of two ammonia-producing bacteria: Bacteroides ovatus and B. vulgatus. The team's findings suggest that inhibiting βII-spectrin could restore normal signaling and slow disease progression, making it a promising target for CRC therapy.
Controversy & Comment Hooks: Could dietary changes and targeting specific gut bacteria be a key to preventing and treating CRC? What are your thoughts on the role of diet and the microbiome in cancer development? Share your opinions in the comments below!
