Cancer patients undergoing chemotherapy or radiotherapy often experience a reduction in their sense of taste. Now, researchers have uncovered a mechanism behind taste bud renewal, paving the way for new treatment strategies for patients with taste dysfunction.
Lead study author Dany Gaillard, of the Anschutz Medical Campus at the University of Colorado Denver, and colleagues publish their findings in the journal PLOS Genetics.
Taste buds are organs containing sensory cells that allow us to experience sweet, salty, sour, bitter and umami (savory) tastes. The majority of taste buds are on the surface of the tongue, though there are some in the cheek, epiglottis and the upper esophagus.
In total, adults have around 2,000-4,000 taste buds, which renew around once a week to maintain taste function. The exact process underlying taste bud renewal, however, has been unclear.
Many patients undergoing cancer treatment – particularly those who have head, neck or colon cancers – experience taste dysfunction. Some patients may be unable to taste at all, while others experience a metallic taste that can make it hard to swallow.
The cancer drugs used to kill cancer cells can damage healthy cells, including taste buds, impairing their ability to renew. “That in turn will alter a person’s sense of taste [potentially] leading to malnutrition, weight loss and sometimes death,” notes senior study author Linda Barlow, also of the Anschutz Medical Campus.
“Thus,” the researchers add, “understanding how taste cells renew throughout adult life, i.e., how newly born cells replace old cells as they die, is essential to find potential therapeutic targets to improve taste sensitivity in patients suffering taste dysfunction.”
By analyzing the tongues of mouse models, the team found that the renewal of taste buds is controlled by a protein in the Wnt signaling pathway, called ß-catenin. This protein is key to producing taste buds in developing embryos, and it also regulates the renewal of epithelial tissue in adults, including that of the mouth, skin and hair follicles.
When it comes to taste bud renewal, the researchers found that ß-catenin regulates the individual stages of taste bud turnover to control their renewal.
“We show that activating this [Wnt] pathway directs the newly born cells to become primarily a specific taste cell type whose role is to support the other taste cells and help them work efficiently,” explains Barlow.
As such, the researchers believe that one way to restore sense of taste in cancer patients undergoing treatment may be to activate the Wnt pathway, prompting taste bud renewal.
Based on their findings, the researchers hypothesize that small molecule cancer drugs that block the Wnt pathway may also cause taste dysfunction, meaning patients receiving such drugs would need complementary treatment to restore sense of taste.
While the team admits there is still much more to learn about the mechanisms underlying taste bud renewal, they believe their findings bring us a step closer to improving cancer patients’ quality of life.
In June 2014, Medical News Today reported on a study that identified stress-activated hormones in the taste buds responsible for detecting sweet, umami and bitter tastes, which the researchers claim may explain emotional eating.