Deserts May Bloom With Cancer-Fighting Compounds

Arizona desert plants' fierce survival mechanisms may hold cancer-fighting secrets

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By
HealthDay Reporter

FRIDAY, June 21, 2002 (HealthDayNews) -- While the rich diversity of rain forests has long drawn scientists in search of life-saving plants, few knew the desert might hold such medical marvels.

However, it takes highly unique survival mechanisms for plants to endure for months under a scorching sun with virtually no water, so researchers are hoping some of those same fierce mechanisms could help the human body survive the equally extreme ravages of cancer.

With Arizona's Sonoran Desert at their doorstep, researchers with the University of Arizona, the Arizona Health Sciences Center and the Arizona Cancer Center have started their search.

They are looking specifically for compounds that might combat increasingly common cancers such as those of the lung, breast, prostate and colon, which involve the growth of numerous tumors and are extremely difficult to treat.

Of particular interest is the fact that the extensive exposure to intense light increases the metabolism in some desert plants, causing them to produce unique secondary metabolites that may hold cancer-fighting -- and specifically tumor-fighting -- qualities.

"Most of the plants in the desert have thorns and waxy leaves to reflect light and heat, but some desert plants don't have those features, so they survive by producing these secondary metabolites," explains Leslie Gunatilaka, professor and associate director of the Southwestern Center for Natural Products Research and Commercialization at the University of Arizona.

"We are looking to these for their potential role in fighting cancer," he says.

In addition to looking at everything from plant parts such as leaves, flowers, fruits and seeds, the researchers are investigating roots and the rich concentrations of unique microorganisms that lurk below ground in what's called the rhizosphere -- the area surrounding root surfaces.

In three years of testing compounds from more than 500 plant species from the Sonoran Desert, the researchers have landed on several compounds that look promising.

The compounds stood out among thousands that were collected by passing screening tests to see if they held the potential of performing critical functions. One such function is whether they can possibly stop the process of angiogenesis, in which tumors begin to produce their own blood supply and start a pattern of exponential growth.

Another criterion for the compounds is the ability to combat so-called heat shock proteins. Such proteins boost the development of cancer by increasing the stability and activity of multiple mutant proteins within a cancer cell.

"We have at least a dozen compounds that have made it through the screening," Gunatilaka says.

One compound derived from a microbe is due to soon move on to experimentation in animal trials at the Arizona Cancer Center, and the National Cancer Institute is evaluating the same compound using their panel of 60 cancer cell lines.

The process isn't a quick or cheap one, however. Gunatilaka says it can take an average of 10 to 20 years and a minimum investment of $350 million to develop an anticancer drug.

Still, American Cancer Society senior medical consultant Dr. LaMar McGinnis says looking where few have looked before is always exciting.

"It's especially intriguing that they are looking into desert compounds that show possible anti-angiogenesis activity because that's an area of research that's of great interest right now," he says. "And looking to microorganisms for this is a pretty unique approach."

McGinnis points to the many drugs that have come from nature.

"It goes back to basic hard drugs, like digitalis (used to treat heart conditions), which has been used for hundreds of years and came from the purple foxglove," he explains. "And some muscle relaxants used in anesthesia even come from compounds that Brazilian Indians used to tip their arrows with."

However, McGinnis cautions that many a promising agent has been brought forward with the hopes of making it to clinical activity, only to fail.

"But we're always hopeful that something as important as Taxol (the popular cancer drug derived from the yew tree) will come forward, and maybe these agents can give us that," he adds.

What To Do

Cancer prevention research extends around the globe. Visit the American Cancer Society's site on Cancer Prevention Studies for much more information.

And you can read about more research taking place in the Sonoran Desert at the Arizona-Sonora Desert Museum.

Sources: Leslie Gunatilaka, Ph.D., professor and associate director, Southwestern Center for Natural Products Research and Commercialization, University of Arizona, Tucson; LaMar McGinnis, M.D., senior medical consultant, American Cancer Society; University of Arizona press release

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