Two bioengineering research professors at
the University of Washington have rediscovered wormwood as a promising
potential treatment for cancer among the ancient arts of Chinese
Research professor Henry Lai and assistant research professor
Narendra Singh have exploited the chemical properties of
a wormwood derivative to target breast cancer cells with
surprisingly effective results. A study in the latest issue
of the journal Life Sciences describes how the derivative
killed virtually all human breast cancer cells exposed to
it within 16 hours.
"Not only does it appear to be effective,
but it's very selective,"
Lai said. "It's highly toxic to the cancer cells but has
a marginal impact on normal breast cells."
Environmental risk factors for cancer are
many. Lifetime exposure to the female hormone estrogen and estrogen-mimicking
chemicals such as some pesticides
and herbicides has been linked to an increase in breast cancer
risk. In 1991, the International Agency for Research on Cancer
classified the pesticide DDT as a possible human carcinogen, and
the U.S. Environmental Protection Agency (EPA) has classified DDT
as a probable human carcinogen.
The manufacture of PCBs, the oily liquids
or solids used as coolants and insulators, was stopped in the United
States in 1977 because of concerns that exposure increases the
risk of cancers, but PCBs are still found in the environment.
Most Americans are exposed every day
to air toxins emitted by motor vehicles, substances that the
EPA says have been proven to cause cancer in humans.
"Benzene, says the EPA, "is a known human carcinogen,
while formaldehyde; acetaldehyde; 1,3-butadiene; and diesel particulate
matter are probable human carcinogens." The EPA has now
classified 1,3-butadiene, a gas used commercially in the production
of resins and plastics, as a known human carcinogen.
The use of the bitter herb wormwood is nothing
new. Used for centuries to rid the body of worms, it is also an
ingredient in the alcoholic beverage absinthe, now banned in most
Artemisinin, the compound that Lai and Singh
have found to fight cancers, isn't new either. It was extracted
from the plant Artemisia annua L., commonly known as wormwood,
thousands of years ago by the Chinese, who used it to combat the
mosquito-borne disease malaria. The treatment with artemisinin
was lost over time but rediscovered during an archaeological dig
in the 1970s that unearthed recipes for ancient medical remedies.
Now widely used in Asia and Africa to fight
malaria, artemisinin reacts with the high iron concentrations found
in the malaria parasite. When artemisinin comes into contact with
iron, a chemical reaction ensues, spawning charged atoms that chemists
call free radicals. The free radicals attack cell membranes, breaking
them apart and killing the single-cell parasite.
About seven years ago, Lai began to hypothesize
that the process might work with cancer, too.
"Cancer cells need a lot of iron to
replicate DNA when they divide," Lai explained. "As
a result, cancer cells have much higher iron concentrations
than normal cells. When we began to understand how artemisinin
worked, I started wondering if we could use that knowledge
to target cancer cells."
Lai devised a potential method and began
to look for funding, obtaining a grant from the Breast Cancer Fund
in San Francisco. Meanwhile, the UW patented his idea.
The thrust of the idea, according to Lai
and Singh, was to pump up the cancer cells with maximum iron concentrations,
then introduce artemisinin to selectively kill the cancer.
In the current study, after eight hours,
just 25 percent of the cancer cells remained. By the time 16 hours
had passed, nearly all the cells were dead.
An earlier study involving leukemia
cells yielded even more impressive results. The cancer cells
were eliminated within eight hours. A possible explanation
might be the level of iron in the leukemia cells. "They have one of the highest
iron concentrations among cancer cells,"
Lai explained. "Leukemia cells can have more than 1,000
times the concentration of iron that normal cells have."
The next step, according to Lai, is animal
testing. Limited tests have been done in that area. In an earlier
study, a dog with bone cancer so severe it couldn't walk made a
complete recovery in five days after receiving the treatment. But
more rigorous testing is needed.
If the process lives up to its early promise,
it could revolutionize the way some cancers are approached, Lai
said. The goal would be a treatment that could be taken orally
on an outpatient basis.
"That would be very easy, and this
could make that possible," Lai said.
"The cost is another plus: At $2 a dose, it's very cheap.
And with the millions of people who have already taken artemisinin
for malaria, we have a track record showing that it's safe."
Whatever happens, Lai said, a portion
of the credit will have to go to unknown medical practitioners,
long gone now. "The fascinating thing is that this was something
the Chinese used thousands of years ago,"
he said. "We simply found a different application."
© 2001 Environmental News Network Inc.