Researchers say a compound in chili peppers could help slow a subtype of breast cancer.
In the United States, breast cancer is also the most common form of cancer in women, regardless of race or ethnicity.
Genetic research has enabled scientists to classify breast cancer into subtypes, which respond differently to various kinds of treatment. These subtypes are categorized according to the presence or absence of three receptors that are known to promote breast cancer: estrogen, progesterone, and the epidermal growth factor receptor 2 (HER2).
Breast cancers that test positively for HER2 typically respond well to treatment and even to some specific drugs. However, there are types of cancer that test negatively for HER2, as well as for estrogen and progesterone - this is called triple-negative breast cancer.
New research, from the Ruhr University in Bochum, Germany, tested the effects of a spicy molecule on cultivated tumor cells of this particularly aggressive cancer type.
Researchers were led by Dr. Hanns Hatt and Dr. Lea Weber, and they collaborated with several institutions in Germany. These included the Augusta clinics in Bochum, the hospital Herz-Jesu-Krankenhaus in Dernbach, and the Centre of Genomics in Cologne.
Examining the effect of spicy molecule on cancer cells
The researchers tested the effect of an active ingredient commonly found in chili or pepper - called capsaicin - on SUM149PT cell culture, which is a model for triple-negative breast cancer.
The scientists were motivated by existing research, which suggests that several transient receptor potential (TRP) channels influence cancer cell growth. As the authors explain, TRP channels are membranous ion channels that conduct calcium and sodium ions, and which can be influenced by several stimuli including temperature or pH changes.
One of the TRP channels that play a significant role in the development of several diseases - and received a great deal of attention from researchers - is the olfactory receptor TRPV1.
Capsaicin has also been shown to induce cell death and inhibit cancer cell growth in several types of cancer, including colon and pancreatic cancer.
In this new study, the researchers aimed to investigate the expression of TRP channels in a vast amount of breast cancer tissue, as well as to analyze and understand how TRPV1 could be used in breast cancer therapy.
Capsaicin activates TRPV1 to inhibit cancer cells
Researchers found several typical olfactory receptors in the cultivated cells. Olfactory receptors are proteins that bind smell molecules together and are located on olfactory receptor cells lining the nose.
The scientists found that the TRPV1 receptor appeared very frequently. TRPV1 is normally found in the fifth cranial nerve, which is called the trigeminal nerve.
This olfactory receptor is activated by the spicy molecule capsaicin as well as by helional - a chemical compound giving the scent of fresh sea breeze.
Dr. Hatt and team found TRPV1 in the tumor cells of nine different samples from breast cancer patients.
Researchers added capsaicin and helional to the culture for several hours or days. This activated the TRPV1 receptor in the cell culture.
As a result of TRPV1 being activated, the cancer cells died more slowly. Additionally, tumor cells died in larger numbers, and the remaining ones were not able to move as quickly as before. This suggests that their ability to metastasize was reduced.
The findings were published in Breast Cancer: Targets and Therapy.
Implications for breast cancer treatment
The authors note that an intake of capsaicin through food or inhalation would be insufficient to treat triple-negative cancer. However, specially designed drugs might help.
"If we could switch on the TRPV1 receptor with specific drugs, this might constitute a new treatment approach for this type of cancer."
Dr. Hanns Hatt, lead study author
Previous studies have shown that the drug arvanil effectively treated brain tumors in mice. Arvanil has a chemical makeup that is similar to the spicy molecule capsaicin and can reduce tumor growth in rodents.
However, the substance cannot be used in humans because of its side effects.
Endovanilloids were also found to activate the TRPV1 receptor in previous studies. These are fat molecules naturally produced by the body, particularly when the brain grows and develops in infants and children.