Scientists say they have taken a big step towards blocking a chemical vital to the growth of many cancers.
They have unpicked the structure of telomerase, an enzyme which, when active, helps keep cells in an “immortal” state.
The chemical is at work in more than nine out of ten types of tumour.
Researchers from Philadelphia’s Wistar Institute, writing in the journal Nature, say their efforts could lead to drugs which switch it off.
All cells in the body have a natural clock – the telomeres – which shorten every time the cell divides.
After a fixed number of divisions in most cells, the telomeres are reduced to a certain length, and the cell cannot continue dividing.
This change is responsible for changes within the ageing body, as cell division slows down.
Some cells, such as stem cells within the embryo, use the chemical telomerase to maintain telomere length.
Many tumours have hijacked the telomerase system to fuel their uninhibited growth.
The Wistar team has found a new way to map the structure of the most active part of the chemical.