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Thursday, 30 December, 1999, 02:42 GMT
Leukaemia 'on-off switch' discovered

lab Laboratory tests could lead to new treatments

An "on-off" cancer switch successfully tested in mice could help develop new treatments for leukaemia in humans.

Scientists say they have identified a gene that forms a vital link in the process leading to leukaemia, and they have managed to demonstrate how it can be turned on and off.

By exposing the genetically-engineered mice to the antibiotic tetracycline, the team at Harvard Institute of Medicine showed they could control the gene known as BCR-ABL1.

Present thinking in cancer research is that there are silent genes, called oncogenes, that when stimulated by a chemical, virus or radiation become activated and cause a previously normal cell to become malignant.

Reverse symptoms

The results of the latest research may point experts towards greater understanding of how tumours are caused and gives hope that it could be possible to reverse leukaemia symptoms if diagnosed early enough.

The gene remained turned off, or inactive, when the antibiotic was put in the mice's drinking water.

When the antibiotic was removed, turning the gene on, the mice quickly succumbed to leukaemia and died within a few weeks. But when the antibiotic was put back in the water, it reversed the effects of the disease.

The research shows that the protein produced by BCR-ABL1 is necessary to trigger and maintain the cancer, the scientists said.

But longer exposure to the gene protein might lead to other cancer-causing abnormalities, which would not be reversible.

The scientists said, in the journal Nature Genetics: "Our findings suggest that complete and lasting remissions may be achieved if the genetic abnormality is abolished or silenced before secondary mutations are acquired."

A spokesman for the Leukaemia Research Foundation said: "BCR-ABL1 is implicated in leukaemia. Any information that sheds light on what causes the disease and what stops it in its tracks has got to be great news."

But he warned that the success in the trial on mice did not necessarily mean the same results would be found in humans. "It would be a long way from being used in clinical trials," he said.

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See also:
03 Dec 99 |  Health
100% success for leukaemia drug
17 Aug 99 |  Health
Child leukaemia linked to infection
31 Mar 99 |  Health
Cloned embryos 'could treat leukaemia'
15 Sep 99 |  Health
Sleepy key to leukaemia

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