New York, Jan 2 (IANS): A small molecule that resets the 'biological clock' of cancer cells can help shrink tumour growth and lead to potential new therapy to treat cancer, says a research.

The molecule called 6-thio-2'-deoxyguanosine (6-thiodG) can stop the growth of cancer cells, the findings showed.

"We observed broad efficacy against a range of cancer cell lines with very low concentrations of 6-thiodG," said Jerry Shay, professor at University of Texas Southwestern Medical Centre in the US.

The researchers did not observe serious side effects in the blood, liver and kidneys of the mice that were treated with 6-thiodG.

The molecule acts by targeting a unique mechanism that is thought to regulate how long cells can stay alive, a type of ageing clock.

This biological clock is defined by DNA structures known as telomeres, which cap the ends of the cell's chromosomes to protect them from damage and which become shorter every time the cell divides.

Once telomeres have shortened to a critical length, the cell can no longer divide and dies though a process known as apoptosis.

However, cancer cells are normally protected from this death by an RNA protein complex called telomerase, which ensures that telomeres do not shorten with every division.

But 6-thiodG can be used to disrupt the normal way cells maintain telomere length.

"Since telomerase is expressed in almost all human cancers, this work represents a potentially innovative approach to targeting telomerase-expressing cancer cells with minimal side effects on normal cells," Shay pointed out.