PLANT DERIVATIVE MAY PROTECT AGAINST LIVER CANCER
(Embargoed for Release until 1 PM, ET, Tuesday, November 1, 2005)
Abstract #2497
A new study shows that a synthetic version of a plant extract prevents
mold toxin-induced liver cancer in rats. The extract, a derivative of
oleanolic acid, is a building block of many plants, including herbs,
and has known anti-inflammatory effects.
Recently created by chemists at Dartmouth College, the man-made
version of oleanolic acid used in the study is dubbed CDDO-Im*.
Investigators at Johns Hopkins teamed up with the Dartmouth chemists to
determine whether the compound could help flush out of the body
chemicals that trigger the development of liver cancer.
The researchers used rat models that simulate precancerous liver tumors
caused by a carcinogen called aflatoxin. Aflatoxin is produced by
microscopic molds found on dietary staples, such as corn and peanuts.
It also is known to cause liver cancer in people infected with
hepatitis B.
"We know that aflatoxin can't be eliminated from our
environment, but we can try to diminish its effects," says Thomas
Kensler, Ph.D., professor of environmental health sciences at the Johns
Hopkins Bloomberg School of Public Health.
In the Hopkins-Dartmouth study, the amount of precancerous
tissue in the rats totaled approximately 1 percent of liver volume –
enough to cause full-blown cancer. Very low doses of CDDO-Im reduced
that fraction by 85 percent. Larger doses of the compound virtually
obliterated all signs of precancerous tissue.
The team's research on gene expression patterns and knock-out mice also
revealed that CDDO-Im works by activating a protein called Nrf2, the
master switch that controls other genes crucial to cell-survival.
"Essentially, CDDO-Im may make cells more resistant to aflatoxin," says
Kensler.
Compared with other compounds used in clinical studies to
prevent liver cancer, the researchers say that a much smaller dose of
CDDO-Im may be needed to have an impact on preventing the disease.
Studies in humans are not yet planned.
*CDDO-Im (1-[2-cyano-3, 12-dioxooleana-1,9 (11)-dien-28-oyl] imidazole)
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发表于 2006-2-17 14:21
