New discovery aids development of cancer treatments

The imaging agent has helped to easily identify four-stranded DNA structures within the nucleus of cells, known as quadruplexes. Researchers had suggested the existence of quadruplexes for some time, but until this breakthrough there had not been an easy way to detect them in living cells.

Researchers are interested in quadruplex DNA for several reasons. Previous studies have suggested that certain cancer-causing genes may be switched on by a shift from a four-stranded structure to the more familiar two-strand double helix. Some researchers have even suggested that this may be a common mechanism for controlling many genes. Until now, scientists have hotly debated how often these quadruplexes occur in living cells.

This new imaging agent will allow researchers to see these structures in cells and investigate their frequency and their roles.

At present, luminescent stains can mark DNA and enable it to be viewed by fluorescent microscopy, but many of these imaging agents are highly toxic and subject to background interferences. This new agent is safer for the cells and acts as a structure-sensitive DNA probe which emits light at a different frequency when bound to four-stranded DNA structures, making them easily identifiable. It also acts as a unique imaging agent for electron microscopy allowing the researchers to study details of the cell nucleus with this technique too.

Dr Jim Thomas, from the University of Sheffield´s Department of Chemistry , who led the study said: "For the first time the luminescent stain provides an easy method to follow DNA structural changes of this kind occurring within living cells. We hope our discovery can help further research into the development of pioneering treatments for a range of diseases."