Molecule programmed to deal double blow to cancer cells


London : Researchers have designed a molecule that tackles malignant cancer cells in mice with a two-pronged attack.

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The ‘designer’ molecule is similar to components of viruses and in this way alerts the immune system. At the same time, it also switches off a specific gene in the malignant cells, driving them to suicide.

“We used this method in order to drive the tumour cells to suicide,” explained Bonn University dermatology professor Thomas Tüting. Every single body cell is equipped with a corresponding suicide programme.

It is activated, for example, if the cell becomes malignant. It dies before it can do any more harm. “But in tumours a gene is active that suppresses this suicide programme,” said Tüting, who heads the experimental dermatology lab. “We have pinpointed this gene and switched it off by using RNA interference.”

For their research project, scientists drew on the latest insights into biology’s box of tricks. A close relative of the nuclear DNA, known as RNA, served them as therapy.

These findings were published in the November issue of the Nature Medicine.

It has only been known that small RNA molecules can basically be used to target certain genes and switch them off. This effect is called RNA interference; Craig Mellow and Andrew Fire from US won the Nobel Prize in 2006 for its discovery.

Researchers also tricked cancer by another route: “We basically ‘disguised’ our RNA,” said Gunther Hartmann, director of the Institute of Clinical Chemistry and Pharmacology. “That is why the immune system took it for the genetic makeup of a virus.”

Many viruses actually do use RNA to store information. So if the body discovers RNA fragments which it takes to be the genetic makeup of a virus, it mounts an attack on them. By means of this trick the body’s defences were prompted to tackle the tumour cells far more aggressively than normal.

RNA is also present in the body’s own cells. For a long time it was not known how the immune system distinguishes between ‘harmful’ and ‘harmless’ RNA. Only two years ago, Hartmann was able to shed light on the problem in a sensational article in the journal Science.

The scientists used this knowledge in order to modify the RNA substance in such a way that it was able to alert the immune system, according to a Bonn release.

“What works in mice does not necessarily prove successful in humans as well,” Tüting warned. “Apart from that, many issues need to be addressed before a trial with cancer patients can even be thought of.”