Curcumin, the major component in the spice turmeric, when combined with the drug cisplatin, enhances the chemotherapy's suppression of head and neck cancer cell growth, according to researchers from the University of California, Los Angeles (UCLA) Jonsson Comprehensive Cancer Center (Molecular Cancer Therapeutics, October 2010, Vol. 9:10, pp. 2665-2675).
A naturally occurring spice widely used in South Asian and Middle Eastern cooking, turmeric has long been known to have medicinal properties attributed to its anti-inflammatory effects. Previous studies have shown it can suppress the growth of certain cancers, said Marilene Wang, M.D., a professor of head and neck surgery, lead author of the study, and a researcher at the cancer center.
"Head and neck cancers, particularly cases diagnosed in a later stage, are terrible cancers that often require very radical surgeries and chemotherapy and radiation," Dr. Wang said in a press release. "They often don't present until late, and the structures in the head and neck are so vital that our treatments often cause disfigurement and severe loss of function. So using nontoxic curcumin as a treatment was a very appealing idea."
A 2005 study by Wang and Eri Srivatsan, Ph.D., an adjunct professor of surgery and a Jonsson center researcher, first showed that curcumin suppressed the growth of head and neck cancer cells, first in cells and then in mouse models. In the animal studies, the curcumin was applied directly onto the tumors in paste form because it did not dissolve in saline, which would have allowed it to be injected.
In need of a better way to deliver the curcumin, the team collaborated with Kapil Mehta, Ph.D., of the M. D. Anderson Cancer Center and found that encapsulating the curcumin in a liposome made the treatment injectable. The curcumin was injected into the tail vein of a mouse, where it circulated into the bloodstream, slowing down and eventually stopping the cancer growth, according to the researchers.
"This was a very positive finding, developing an efficient way to deliver the treatment," Dr. Wang said. "Our study also showed that the curcumin was very well tolerated."
In this most recent study, the team wanted to combine the curcumin with the chemotherapeutic drug cisplatin, which is very toxic at the doses needed to fight head and neck cancers, damaging kidneys, the ears, and the bone marrow. They hoped that if they added curcumin to the mix, they might be able to lower the cisplatin dose and cause less organ damage. Their finding, that the curcumin made the cisplatin work better, was very promising, Dr. Wang said.
"We knew that both the curcumin and the cisplatin, when given alone, had an effect against head and neck cancers," Dr. Wang said. "This finding that curcumin enhances cisplatin means that, in the future, we may be able to give this chemotherapy in lower doses."
"The mechanisms of the two agents through different growth signaling pathways suggest potential for the clinical use of subtherapeutic doses of cisplatin in combination with curcumin, which will allow effective suppression of tumor growth while minimizing the toxic side effects," the study authors wrote.
The study found that curcumin suppressed head and neck cancer growth by regulating cell cycling, Srivatsan said. It binds to an enzyme and prevents the enzyme IKK, an inhibitor of kappa B kinase, from activating a transcription factor called nuclear factor kappa B (NFÎşB), which promotes cancer growth. Cisplatin's suppressive action involves a different pathway through the tumor suppressor proteins p16 and p53, both proteins that again inhibit the activity of cancer growth promoter NFÎşB.
"We needed to know the mechanism to help us translate this from the lab into the clinic," Dr. Wang said. "That information will help us make better decisions on how to design therapies."
The next step in the clinical setting is to give patients oral curcumin prior to surgery and, after surgery, to study the excised tumors to determine curcumin's effect on tumor markers, specifically whether there is reduced expression of markers such as growth promoting NFÎşB. They also will be monitoring to determine if the curcumin results in any side effects. After that, the team would give curcumin to patients also getting chemotherapy and radiation to see if the tumor suppression found in the cells lines and mouse models can be replicated in humans.
Although turmeric is used in cooking, the amount of curcumin needed to produce a clinical response is much larger -- about 500 milligrams. Expecting a positive effect through eating foods spiced with turmeric is not realistic, the researchers said.
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