Team observes super-fast process

A team of researchers combining chemistry and bioscience have observed how a light-activated compound alters the structure of DNA, which could lead to new cancer treatments.

Photo-dynamic therapy, a form of treatment for conditions including several cancers and psoriasis, uses light to activate a drug in a specific area of the body and can reduce the side effects observed in conventional anti-cancer treatments. Now, scientists working in Reading and Dublin have identified a new way of finding out how such compounds work. It is difficult to observe such fast processes in living cells but the much simpler environment of a DNA crystal has enabled the team to watch the process in great detail. The crystals contain a ruthenium compound which is bound to a short piece of DNA. This class of compound is used in DNA-sensing and is of interest to the pharmaceutical industry for cancer treatment.

The researchers found that by using infrared radiation, they could get a snapshot of the process – which occurs in half a billionth of a second – that takes place when light is shone on the crystals. This activates the compound, making it cause damage to DNA. This research was carried out using two UK central research facilities: the laser facilities in the Central Laser laboratory of the Science and Technology Facilities Council (STFC) and Diamond Light Source, the UK national synchrotron facility.

Dr Susan Quinn, from the School of Chemistry at University College Dublin, the lead author of the study, said: “These results are very exciting as they demonstrate the ability to follow the flow of electrons from DNA to a molecule whose exact position is known and this is an enormous advantage in the study of the early events that lead to DNA damage.” Professor Christine Cardin, from the University of Reading, a nucleic acid crystallographer, led the UK team, which has received major funding from the Biotechnology and Biological Sciences Research Council to support the work, which included co-author Dr James Hal Prof Cardin said: “Among other things, the insights from this study will feed into the development of new drugs that target cancerous tissue, without damaging healthy tissue around it.”A key element of the funding for the collaboration has been provided by the Royal Irish Academy-Royal Society exchange programme, running since 2008 between Trinity College Dublin and the University of Reading.