People’s reaction to eating spicy foods ranges from the euphoric demand for more to the tongue-sweltering search for fire-snuffing edibles. Most spicy dishes owe their heat to peppers from the genus Capsicum, with species ranging from the nonspicy bell pepper to the current title holder of world's hottest pepper, the Carolina Reaper. For years researchers have been interested in the chemical compound—capsaicin—that makes many of these peppers seem spicy to those brave enough for the experience. While capsaicin’s uses range from pain reliever to personal defense sprays, investigators at Ruhr University Bochum (RUB) in Germany have just discovered that the active spicy pepper ingredient also inhibits the growth of cultivated breast cancer cells.
The findings from this study were published recently in Breast Cancer: Targets and Therapy in an article entitled “Expression and Functionality of TRPV1 in Breast Cancer Cells.”
“This study focused on the expression and functionality of TRPV1 [transient receptor potential channel], a nonselective cation channel that was found to be expressed in different carcinoma tissues,” the authors wrote. “Next-generation sequencing analyses revealed the expression of TRPV1 in several native breast cancer tissues, which was subsequently validated via reverse transcriptase-polymerase chain reaction.”
The researchers carried out experiments using the SUM149PT cell line, which is a model system for the triple-negative breast cancer—a particularly aggressive type of tumor. Chemotherapy is, at present, the only available treatment for this type of cancer.
In the cultivated cells, the RUB team noticed several typical olfactory receptors, yet TRPV1—which is typically found in the fifth cranial nerve—occurred very frequently in the tumor cells. Interestingly, the TRPV1 receptor is activated by capsaicin as well as by helional, a chemical compound used as a perfume in soap and laundry detergent often being described as having a scent of fresh sea breeze. In addition to the cultured cells, the German scientists were able to confirm the existence of TRPV1 in tumor cells from nine different patients who have breast cancer.
The researchers were determined to see what consequence, if any, activating the TRPV1 channel had on the cultured tumor cells.
“Activation of TRPV1 by its ligand capsaicin was associated with the growth inhibition of some cancer cell types; however, the signaling components involved are complex,” the authors penned. “In this study, stimulation by the TRPV1 agonist, capsaicin, of SUM149PT cells, a model system for the most aggressive breast cancer subtype, triple-negative breast cancer, led to intracellular calcium signals that were diminished by the specific TRPV1 antagonist, capsazepin. Activation of TRPV1 by capsaicin caused significant inhibition of cancer cell growth and induced apoptosis and necrosis.”
After adding capsaicin to the culture medium for a period of several hours or days, the scientists noticed the cancer cells divided more slowly or many died off in larger numbers. Additionally, cells that survived the capsaicin treatment were no longer able to move as quickly as before—suggesting that their ability to form metastases in the body was impeded.
“If we could switch on the TRPV1 receptor with specific drugs, this might constitute a new treatment approach for this type of cancer,” concluded senior study investigator Hanns Hatt, Ph.D., professor of cell physiology at RUB.