Artemisinin-Transferrin Is Potent Anticancer Drug

Researchers have created a potent anti-cancer drug by binding the anti-malaria drug, artemisinin, to the iron transfer protein, transferrin.

Artemisinin, which has been used since antiquity to treat malaria, reacts with iron to form free radicals that kill cells. Since rapidly growing cancer cells require more iron than normal cells, it had been speculated that they would be more susceptible to the killing effect of the drug. Earlier studies have indicated that this theory is correct.

In the current study, published in the January 28, 2005, issue of Life Sciences, investigators at the University of Washington (Seattle, USA; www.uwashington.edu) described a procedure to boost the effectiveness of artemisinin by increasing the likelihood of its incorporation by cancer cells and at the same time providing it with a ready source of iron.

The iron transportation protein transferrin is moved into cells via receptor-mediated endocytosis, and cancer cells express significantly more transferrin receptors on their cell surface and endocytose more transferrin than normal cells. The investigators created a hybrid molecule by covalently attaching artemisinin to transferrin. The new molecule (holotransferrin-tagged artemisinin) was designed to be readily incorporated into cancer cells via the transferrin receptors and to carry a supply of iron for artemisinin to convert into free radicals.

They tested the compound on a human leukemia cell line (Molt-4) and normal human lymphocytes, and found that holotransferrin-tagged artemisinin, when compared to artemisinin, was very potent and selective in killing cancer cells.

Senior author Dr. Henry Lai, professor of bioengineering at the University of Washington, said, "By itself, artemisinin is about 100 times more selective in killing cancer cells as opposed to normal cells. In this study, the new artemisinin compound was 34,000 times more potent in killing the cancer cells as opposed to their normal cousins. So the tagging process appears to have greatly increased the potency of artemisinin's cancer-killing properties.”



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