Antarctica May Hold Cancer Key Posted Tuesday, February 1, 2005 by arjuna
Published: Feb 1, 2005


By KURT LOFT

TAMPA - A University of South Florida scientist may have won another battle in the war on cancer.

Organic chemist Bill Baker has isolated a compound in an exotic marine creature that shows promise in treating melanoma, the most deadly form of skin cancer.

``This is the sort of thing we chemists wait for,'' Baker said Monday.

Along with fellow scientists from the University of Alabama, Baker has been working in Antarctica, where animals have evolved to survive in the extreme environment.

One such critter, a spongelike tunicate, is thought to be a rich source of compounds that might help people fend off disease.

Baker's team extracted a defensive toxin that disrupts the physiological pathways in predators. Although the toxin is bad news to anything wanting to munch on the tunicate, also called a sea squirt, the compound acts chemotherapeutic in the laboratory.

Scientists at the National Cancer Institute in Maryland tested the material against more than 60 kinds of cancer cells. The compound, called Palmerolide A, had little effect on all but one: It zeroed in on melanoma cells and killed them.

``What you look for is a pattern,'' Baker said. ``If you have a cytotoxin that kills a lot of different cancer cells, that's not what you want. What you do want is only a few cell lines that show sensitivity to the compound.''

Baker got it.

``Melanoma not only was selective, but the compound was potent,'' he said. ``That's what's really neat.''

Baker and his colleagues have made eight trips to Antarctica to study animals and plants for possible pharmaceuticals. About 60 percent of marketed drugs come from natural sources. The team combines chemical ecology, the study of natural chemicals, and bioprospecting, the search for those chemicals in living tissue.

A certified diver, Baker collected tunicate specimens more than 100 feet below the surface in waters that was 28 degrees Fahrenheit. Harvesting the animals was difficult, but Baker needed only a small amount of the compound for testing.

He made sure the National Cancer Institute got a large batch to study.

``Sometimes you're lucky to get a few milligrams of a substance,'' said Bob Schultz, an organic chemist with the institute's developmental therapeutics program. ``But in this case, Baker gave us more than 100 milligrams, so we have plenty of material to work with. If a natural product shows promise, it's good to have it in large quantities.''

The compound will require years of further study before it can be tested on animals, NCI officials said.

Reporter Kurt Loft can be reached at (813) 259-7570.
This story can be found at: http://news.tbo.com/news/MGB311RKN4E.html