Scientists said the accepted view of how tumours develop - by rapid, uncontrolled cell division - can now be seen in a new light: cancers may grow because some cells have lost their natural ability to commit suicide.
The Imperial Cancer Research Fund said its findings heralded a new era in drug development. Fighting cancer in future could be done by reminding tumour cells to die.
Dr Gerard Evan, leader of the ICRF research team, said the significance of cell suicide has until now been ignored.
'Cell death was considered to be an extremely bad thing. No one considered it as constructive. It may be that a whole new set of therapies open up based on cell death,' he said.
Every cell in the body is programmed to die and each hour an average healthy person loses about 1,000 million cells, Dr Evan said.
The body is involved in a delicate balancing act between cell division, which is necessary for growth, and cell death, which is necessary for sculpting the body into the required shape.
Scientists found that a gene - called c-Myc - is involved in controlling both cell division and death.
'We think the mechanism functions somewhat like a dual-key system on a nuclear missile. The keys come in the form of signals from surrounding cells. One signal turns on cell growth but at the same time switches on an order to self-destruct. The second signal overrides the self- destruct signal,' Dr Evan said.
The traditional view of tumours is that they form because of rapid, uncontrolled cell divison, he said.
'In the past we cancer researchers have concentrated almost entirely on cell division and regarded cell death only as a curiosity. As a consequence, we have largely ignored half the picture of what makes a cell cancerous.'
Experiments by Liz Harrington at the ICRF demonstrated that an important signal for cell suicide is a substance found in the body called IGF-1 (insulin-like growth factor). The research is published in the current issue of the EMBO Journal.
Dr Evan said: 'Clinically this opens up a whole new vista of possibilities for treatment . . . If we could correct the errors that cancer cells have in their death machinery we might well trigger the spontaneous disappearance of the tumour.'Reuse content