Researchers with UCLA`s Jonsson Cancer Center have found that 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.
In India, women for years have been using turmeric for medicinal purposes, as an anti-aging agent rubbed into their skin, to treat cramps during menstruation, as a poultice on the skin to promote wound healing and as an additive in cosmetics, said scientist Eri Srivatsan, an adjunct professor of surgery and a Jonsson Cancer Center researcher.
Srivatsan, along with Dr. Marilene Wang, a professor of head and neck surgery, lead author of the study and a Jonsson Cancer Center researcher, has been studying curcumin and its anti-cancer properties for six years.
A 2005 study by Wang and Srivatsan 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 tumours 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 Dr. Kapil Mehta of M.D. Anderson Cancer Center and found that encapsulating the curcumin in a liposome, an artificially prepared vehicle that enclosed the spice component within its membrane, made the treatment injectable.
The curcumin was injected into the tail vein of a mouse, where it circulated into the blood stream, slowing down and eventually stopping the cancer growth, a study in 2008 found.
"This was a very positive finding, developing an efficient way to deliver the treatment," Wang said. "Our study also showed that the curcumin was very well tolerated."
In this 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, Wang said.
"We knew that both the curcumin and the Cisplatin, when given alone, had an effect against head and neck cancers. This finding that curcumin enhances Cisplatin means that, in the future, we may be able to give this chemotherapy in lower doses.," Wang said.
The study noted that "the mechanisms of the two agents through different growth signaling pathways suggest potential for the clinical use of sub-therapeutic doses of Cisplatin in combination with curcumin, which will allow effective suppression of tumor growth while minimizing the toxic side effects."
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 (NFêB), 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 NFêB.
"We needed to know the mechanism to help us translate this from the lab into the clinic. That information will help us make better decisions on how to design therapies," Wang said.