AICR ScienceNow
Volume 30
Fall 2009

Curcumin: Spicing Up Cancer Prevention

From lab to clinical studies, the research showing curcumin may play a role in fighting cancer is gaining strength.

As the main component in the Indian curry spice turmeric, curcumin is one of many dietary factors researchers are cooking up in the lab as a means to prevent and treat cancer. Over the last several decades, laboratory studies have shown that curcumin can promote cancer cell death and slow the growth of tumors. Now, researchers are rigorously testing its efficacy and gaining a clearer understanding of how curcumin may play a role in cancer development.

A Multitude of Mechanisms

Curcumin, which gives curry its golden color, is the main biologically active phytochemical compound of turmeric. Long believed to benefit general health, research suggests that curcumin aids in healing by ameliorating the chronic inflammation associated with a multitude of ailments and illnesses, from toothaches to cardiovascular disease.

According to Bharat Aggarwal, PhD, Professor of Cancer Medicine at the University of Texas M.D. Anderson Cancer Center, curcumin is unique and versatile as an anti-cancer agent because it can attack multiple targets linked with cancer promotion at once. Hundreds of cell and animal studies suggest that curcumin inhibits the development of many cancers, including pancreatic, colon, prostate, liver, esophageal, and multiple myeloma.

Years of researching curcumin’s role in cancer prevention led to Aggarwal studying the component synergistically with chemotherapy to slow the spread of cancer. “We have not been able to find a cancer we can’t effectively treat in the laboratory with curcumin,” said Aggarwal, who is presenting his research on how curcumin and other spices effect cancer development at the annual AICR research conference in November.

“Curcumin doesn’t knock out all the light bulbs that cause cancer, it merely turns them down.”

“We’ve even been able to slow the progression of pancreatic cancer, one of the most lethal cancers. What’s more, we haven’t been able to come up with a dose that causes toxicity.” Cancer is usually caused by the disruption of multiple genes working together, like the many light bulbs on a Christmas tree that cause it to be bright, he said. “Curcumin doesn’t knock out all the light bulbs that cause cancer, it merely turns them down.”

Curcumin’s anticancer capabilities may lie in its ability to act as an effective agent that can affect multiple cell signaling pathways including those that mediate inflammation, survival, proliferation, invasion and metastasis. Studies have demonstrated that it blocks or inhibits three powerful proteins responsible for the regulation of inflammation in many types of cancers: nuclear factor kappa B (NF-kB), TNF and COX-2.

Laboratory studies have shown NF-kB also plays a key role in cancer by regulating genes that promote proliferation and prevent apoptosis. By interrupting the pathway that causes chemoresistance of cancer cells, curcumin also may help chemotherapy work more effectively to shrink tumors and hinder metastasis.

Curcumin + Iron

Although curcumin appears effective and safe, it has limitations based on its molecular make-up, a research area that Suzy Torti, PhD, Professor of Biochemistry at Wake Forest University, is working to address. “One of the challenges with curcumin is that it is poorly absorbed in the blood,” she said.

With support from AICR, Torti is also exploring how iron status may impact the effectiveness of curcumin as a cancer preventive agent. Her lab studies have found that curcumin acts as an iron chelator, binding tightly to iron. Curcumin’s effectiveness as a chemopreventive agent could depend on the level of iron in the body. “Curcumin might interact with iron and negate its activity, so curcumin supplements may not be appropriate for all cancer patients, especially those on the threshold of anemia,” she said.

Because iron can promote cancer growth, Torti hypothesizes that curcumin’s ability to chelate iron could explain in part how it limits tumor growth. Using mouse models of cancer, she is looking at how low- and high-iron diets affect curcumin-fed mice. If curcumin prevents tumors by chelating iron, those on a low-iron diet should have even less cancers than those on a high-iron diet.

Ongoing Research

In recent years, curcumin has moved into clinical studies, yet the research is still preliminary and much of it is ongoing. Overall, results in studies are encouraging for curcumin’s role in cancer prevention and possibly as an adjuvant to chemotherapy, yet research is still in the early phases and many questions remain. Also, a minority of studies suggest that turmeric consumed during cancer treatment may interfere with treatment.

Until research is more conclusive on amounts and mechanisms, adding dietary sources of curcumin can’t hurt for cancer prevention, say researchers, yet cancer patients should always check with their health professional. To include dietary sources of curcumin, nutritionists suggest sipping tea with turmeric or eating dishes that contain curry.

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