The circles of DNA that cause cancer
By 
Rachel Brazil2025-03-24T10:37:00
Ring-shaped extrachromosomal DNA is implicated in many cancers. Rachel Brazil talks to the scientists trying to uncover their secrets
It was back in 1962 that DNA circles were first spotted in cancer cells. The ‘bunch of dots’ of DNA they saw in the microscope, separated from the chromosomes, but still within the cell nucleus, were often in pairs (now we know because they were replicating). Interest faded in what is now called extrachromosomal circle DNA (ecDNA), until the last decade. Armed with modern molecular biology and genomics tools, researchers have started to realise their importance. These circles might explain why some cancers are more lethal than others.