Curcumin's anti-cancer mechanism proposed
by which curcumin, the active ingredient in the turmeric spice, may
protect against cancer.
The study, published in the journal Cancer Research, adds weight to the growing body of science linking consumption of the spice to decreased risk of certain cancers, like colorectal and prostate cancer. "Our observations help to… identify a mechanism by which curcumin functions as an anticancer agent," wrote lead author Mao Li. The anti-cancer effects of spices from curcumin to red chili pepper capsaicin have been consistently researched. The lowest incidence of both colorectal and prostate cancers is observed in Asia and the Far East, in particular India and China, and this has been linked to high dietary intake of compounds like turmeric. Using PC-3 human prostate cancer cell lines grown in vitro, the researchers observed that curcumin decreased the expression of a protein associated with malignant tumor formation called MDM2. The turmeric extract was also found to increase the expression of a protein that increases programmed cell death (apoptosis) of the cancer cells. To test the efficacy of curcumin in vivo, the researchers grafter PC-3 prostate cancer cells into a group of nude mice, and then assigned to receive either curcumin or cottonseed oil (placebo) orally for five days per week for four weeks. The curcumin-fed mice were further divided into three groups with five animals per group. One group continued to receive only curcumin supplements, while the others received curcumin in conjunction with the chemotherapy agent gemcitabine or curcumin in conjunction with radiotherapy. "Curcumin inhibited growth of PC3 xenografts and enhanced the antitumor effects of gemcitabine and radiation. In these tumors, curcumin reduced the expression of MDM2," wrote the researchers. "Down-regulation of the MDM2 oncogene by curcumin is a novel mechanism of action that may be essential for its chemopreventive and chemotherapeutic effects," they concluded. Writing on urotoday.com, Ricardo Sanchez-Ortiz, MD, who was not involved in the study, said: "These exciting data suggest that this dietary supplement should be studied in combination with traditional forms of chemotherapy or radiotherapy in tumours dependent on the MDM2 pathway." Source: Cancer Research March 2007, Volume 67, Number 5, Pages 1988-1996, doi: 10.1158/0008-5472.CAN-06-3066 "Curcumin, a Dietary Component, Has Anticancer, Chemosensitization, and Radiosensitization Effects by Down-regulating the MDM2 Oncogene through the PI3K/mTOR/ETS2 Pathway" Authors: M. Li, Z. Zhang, D.L. Hill, H. Wang, and R. Zhang