"We could completely inhibit the growth of the tumor if we used a big enough dose," said study co-author Bharat B. Aggarwal, chief of the Cytokine Research Section in the Department of Experimental Therapeutics at the University of Texas M.D. Anderson Cancer Center in Houston. His report is set to appear in the Aug. 15 issue of Cancer.

Zeroed in on Overactive Molecule

Aggarwal and his colleagues exposed three different cell lines of melanoma to curcumin, which is found in turmeric, a spice used in curry dishes. Exposure to curcumin decreased the cell viability of all three cell lines, they found.

They zeroed in on a molecule called NF-kappa B, which is known to be overactive in several types of tumors, including melanoma. The turmeric shut down the molecule and that lead to inhibition of the tumor growth, Aggarwal explained.

In other preliminary research, including some by Aggarwal's team, turmeric has proven useful in treating multiple myeloma, as well as breast and pancreatic cancers.

The new findings were praised by Costas Koumenis, an associate professor of radiation oncology at Wake Forest University School of Medicine. "I think it's an interesting and provocative study," he said. "It shows some new insight into how turmeric is working to inhibit the growth of melanoma cells."

Koumenis is studying whether curcumin can be used to enhance radiation therapy in deadly brain tumors called gliomas and other tumors in animals.

Reduced Rates of Colon Cancer

The Texas researchers also pinpointed exactly how the spice ingredient works to kill tumor cells, he said. "It gives us a better understanding of the mechanism of how it works to inhibit melanoma growth."

But he cautioned that the study was done in the lab, and the spice must be tested on animals, and eventually people, before it is proven to be effective.

For the past 20 years, Koumenis said, turmeric has been studied, mostly as an agent to prevent cancer. For instance, some researchers have found an association between diets rich in curcumin and reduced rates of colon cancer. But more recently, the focus has shifted to study the spice as a cancer treatment.

More information: To learn more about melanoma, visit the American Cancer Society.