The Double Life of the 'Happiness Chemical'
Serotonin has long been celebrated as the brain's happiness chemical, famous for regulating mood and emotional wellbeing. However, revolutionary scientific discoveries are now revealing this familiar molecule plays a surprisingly different role in cancer development - one that operates completely independently from its brain functions.
While most people associate serotonin with mental health, approximately 95% of the body's serotonin is actually produced in the gut, not the brain. From there, it travels through the bloodstream to various organs and tissues including the liver, pancreas, muscles, bones, fat tissue and immune cells.
From Gut to Genes: Serotonin's Cancer Connection
In 2019, researchers at the Icahn School of Medicine at Mount Sinai in New York made a startling discovery. They found that serotonin can actually enter cells and interact directly with DNA, binding to molecular switches that control whether genes are active or inactive.
Subsequent studies have demonstrated that this mechanism can switch on genes involved in cancer growth. This serotonin-driven process has been observed in brain, liver and pancreatic cancers, with researchers suspecting it may influence many other cancer types.
Scientists at the University of Limerick in Ireland, including postdoctoral researcher Jeremiah Stanley, are currently investigating this interaction to better understand how serotonin influences cancer development. Their work focuses on identifying the specific sites where serotonin binds to cancer-related genes.
New Frontiers in Cancer Treatment
This research could pave the way for revolutionary epigenetic therapies - treatments that control which genes are switched on or off without altering the DNA sequence itself. Such therapies aim to reprogramme cancer cells by directly adjusting their gene activity, potentially attacking tumours with greater precision than current aggressive treatments like chemotherapy and radiotherapy.
Researchers are also exploring how serotonin produced in the gut reaches cancer cells. Understanding this pathway could lead to new approaches for managing serotonin levels in patients, including dietary changes, maintaining a healthy gut microbiome, or using antidepressant drugs called selective serotonin reuptake inhibitors (SSRIs).
These drugs work by blocking the tiny transport channels that allow serotonin to enter cancer cells, preventing it from reaching DNA and causing cancer-promoting effects. Early studies suggest SSRIs could have beneficial effects against certain cancers, though larger clinical trials are needed for confirmation.
Crucially, the serotonin that influences mood in the brain appears to operate independently from the gut serotonin driving cancer growth. People taking SSRI antidepressants such as Prozac, Celexa and Zoloft need not worry their medication may be driving cancer - in fact, early evidence suggests the opposite may be true.
While significant challenges remain, including developing accurate delivery systems for epigenetic drugs and validating results in human trials, this research opens exciting new avenues for cancer treatment. A more complete understanding of serotonin's functions across mood, metabolism and cancer could guide the development of more precise and effective therapies in the future.
