High tech twist to ancient drug kills cancer

Using a high tech process to modify an ancient drug called artemisinin, researchers have created a compound that is highly lethal to cancer cells, but causes little harm to normal cells, according to a report in the journal Life Sciences.

Artemisinin, a substance derived from wormwood that is used to treat malaria in China, reacts with iron to produce "free radicals" - toxic compounds that can destroy cells.

Because cancer cells take up more iron than do normal cells, they should be more susceptible to the toxic effects of artemisinin, Dr. Henry Lai from the University of Washington in Seattle, and colleagues reasoned. In an earlier study, Lai's team showed that, in fact, this was true.

In the current study, the researchers hypothesized that they could improve the anti-cancer potency of artemisinin further by attaching or "tagging" it to transferrin, a protein that picks up iron in the blood and then is transported into cells, especially cancerous ones. Once in the cell, transferrin releases the iron, leaving it free to interact with artemisinin and cause the deadly reaction.

The investigators tested the "artemisinin-tagged transferrin" on human leukemia cells and on normal human immune cells. As hoped for, the compound destroyed the leukemia cells, but had little effect on the normal cells.

"By itself, artemisinin is about 100 times more selective in killing cancer cells as opposed to normal cells," Lai said in a statement. By contrast, "the new artemisinin compound was 34,000 times more potent in killing cancer cells as opposed to their normal cousins. So the tagging process appears to have greatly increased the potency."

The next step will be to evaluate the new compound in animal studies, the researchers note.

SOURCE: Life Sciences, January 28, 2005.