Scientists are closer to developing better cancer drugs after deciphering the structure of a protein critical to the growth of almost all human tumours.

The successful decoding of telomerase, which allows cancer cells to thrive and divide, may lead to new therapies that can kill tumours by blocking their activity, while leaving healthy tissue untouched. As telomerase has the potential to rejuvenate cells, the discovery may also lead to treatments that slow the ageing progress.

Telomerase has been a chief target for cancer research for more than a decade because of its importance in the growth of most tumours, but drugs designed to inhibit it have performed poorly in clinical trials. The discovery of the protein’s structure should help scientists to develop agents that bind to it more precisely, blocking its functions and destroying tumours.

“Telomerase is an ideal target for chemotherapy because it is active in almost all human tumours, but inactive in most normal cells,” said Emmanuel Skordalakes, of the Wistar Institute in Philadelphia, who led the study. “A drug that deactivates telomerase would likely work against all cancers, with few side-effects.”

Telomerase allows cells to replace important structures called telomeres – chunks of repetitive DNA that sit at the end of the chromosomes that carry genes. These work like the tape at the end of a shoelace, to prevent the strings of DNA that make up chromosomes from unravelling.

In adult tissue, telomerase is generally inactive, but in most cancers it starts to work again. This allows cancerous cells to divide unchecked, and effectively to achieve immortality by replacing their telomeres so they do not age.

The research, which is published in the journal Nature,should assist greatly the design of telomerase-inhibiting drugs. The team used a gene from a red flour beetle to produce telomerase in large and stable quantities, then used X-ray crystallography to identify the structure of its active region.

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