Researchers have identified a new compound called CDDO-Im that protects against the development of liver cancer in laboratory animals.
The compound appears to stimulate the enzymes that remove toxic substances from the cells, thereby increasing the cells' resistance to cancer-causing toxins. The National Institute of Environmental Health Sciences and the National Cancer Institute, agencies of the federal National Institutes of Health, provided funding to researchers at the Johns Hopkins Bloomberg School of Public Health for the two-year study.
The compound's effectiveness at very low doses suggests it may have similar cancer-fighting properties in humans. Researchers believe it may be particularly effective in preventing cancers with a strong inflammatory component, such as liver, colon, prostate and gastric cancers. The compound could eventually play a preventive role in a wide range of other illnesses such as neurodegenerative disease, asthma and emphysema.
The study results are featured on the cover of the February 15, 2006 issue of the journal Cancer Research.
"The results show that the potency of this compound is more than 100 times as great as that of other chemopreventive agents in protecting against cancer," said NIEHS Director David A. Schwartz, M.D. "This protective effect, combined with the compound's anti-inflammatory properties, make it an exciting avenue for the prevention of other diseases as well."
CDDO-Im belongs to a class of cancer-fighting compounds called triterpenoids. It is a synthetic compound derived from oleanolic acid, a naturally occurring substance found in plants all over the world. Research with other oleanolic derivatives showed marked anti-tumor activity in both animals and humans.
To test the effectiveness of CDDO-Im, researchers treated laboratory rats with either 0.1, 0.3, 1.0, 3.0 or 10 micromole doses of the compound. Two days after treatment with CDDO-Im, the rats were treated with aflatoxin, a naturally occurring toxin that causes liver cancer in animals.
Evaluation of the rat livers showed that the lowest concentration of CDDO-Im led to an 85 percent reduction in pre-cancerous lesions, abnormal growths that have a greater likelihood of developing into actual cancers. "This compound has a much greater effect at a far lower dose than any other compound currently used for preventing aflatoxin-induced cancer in humans," said Thomas Kensler, Ph.D., a cancer biologist with the Johns Hopkins Bloomberg School of Public Health and lead author on the study.