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A TROJAN HORSE

Illustration

IN THE FIGHT AGAINST CANCER

DRUG DELIVERY: Danish researchers have found a method of delivering drugs to cancer cells using sugar-coated RNA

In 2006, Professors Andrew Z. Fire and Craig C. Mello won the Nobel Prize in medicine for their discovery of how individual gene expression in our cells is controlled. Their work has been hailed as a breakthrough. By identifying the portion of human DNA that synthesises faulty proteins, which results in cancer cells, Fire and Mello have succeeded in creating the RNA that regulates the synthesis of the problematic proteins, thereby laying the foundation inhibiting the formation of the diseased cells.

However, actually getting the RNA into these cells is a major task, since they have a formidable ability to prevent such attempts. Considerable cunning is required, and Professor Jørgen Kjems and his team at the University of Aarhus, Den-mark, have plenty of it.

Trojan Horse
Inspired by the legend of the Trojan Horse, the Aarhus team has found a method of delivering RNA molecules to the diseased cells so that the disease process is arrested.

“Comparisons with the Trojan Horse are appropriate,” says Professor Kjems. “We play on the diseased cells’ appetite for sugar. A cancer cell loves sugar, and so by “sugar-coating” the RNA molecule, we can smuggle the disease treatment into the cell.”

Sugar from shrimps
Today’s Trojan Horse drama is being acted out at much smaller scale than its historical precedent, namely nanoscale, with a substance derived from shrimps.

“The shells of shrimps and other marine crustaceans are an abundant source of the complex sugar chitin, which provides an excellent starting material for gaining sly access to diseased cells,” says Jørgen Kjems. “By chemically modifying the chitin we can make chitosan, which we can combine with the RNA to form nanosize particles that are programmed to find their way to the diseased cells. Here they attach themselves to the cell surface, which folds around the sugar coating. Inside the cell, enzymes break down the sugar and release the RNA which is now free to do its repair work.”

Green mice
The groundbreaking discovery by Professor Kjems and his team of the RNA delivery method may have future importance for the treatment of arthritis, infections and various forms of cancer. Until now they have used “green mice”. These are diseased mice into which a gene from a green jellyfish has been inserted. The gene causes the mice to glow green under special light conditions. When the mice are treated with the RNA, the places where it has an effect turn white.

http://www.mb.au.dk/en/

Photo
Professor Jørgen Kjems

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Version 1. 22-05-2007
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