Scientists discover human DNA that act as a traitor to body's defences

Cancer Research UKApr 28 2010

'Traitor' human DNA helps viruses cause cancer

Cancer Research UK-funded scientists have discovered that stretches of human DNA act as a traitor to the body's defences by helping viruses infect people and trigger cancer-causing diseases, according to a study published in Nature Cell Biology today.

The researchers discovered that viruses can exploit the body's DNA - dampening its antiviral immune response and allowing infection to take hold more easily.

Scientists funded by Cancer Research UK and the Medical Research Council at the UCL Cancer Institute showed this happened with the Kaposi sarcoma herpesvirus which causes the cancer Kaposi Sarcoma and also with the herpes simplex virus which causes cold sores.

Our immune system uses multiple ways to prevent or clear infection. In parallel, viruses have also evolved highly sophisticated counter measures to escape from the human immune defence. The team has discovered that viruses exploit tiny molecules derived from human DNA called microRNAs, to make cells more susceptible to viral infection. MicroRNAs are mostly found in parts of the human genome which do not generate proteins - initially thought to be 'junk DNA'.

Lead author, Cancer Research UK's professor of cancer medicine at UCL, Chris Boshoff, said: "We are investigating microRNAs as future therapeutic targets, and targeting cellular microRNAs could be a potential way to prevent or treat cancer-causing infection from viruses."

Dr Dimitris Lagos, study author, based at the Cancer Research UK Viral Oncology Laboratory at UCL's Cancer Institute, said: "The viruses we tested have evolved with humans for millions of years and use a variety of biological tricks to establish life-long and mostly harmless infections. We discovered that it is likely that other viruses - which can cause diseases including cancer exploit the tiny molecules present in everyone's DNA - called microRNA - to turn cells into a viral 'hotel' which they can check into, to cause infection and spread."

Dr Lesley Walker, director of cancer information, said: "This is intriguing research which unravels an ancient molecular mystery - and provides a hot new therapeutic target to prevent cancer-causing infection from viruses.

"Infectious viruses and human DNA have been around for so long that a relationship has developed and viruses can cheekily use the bits of our DNA that we often think of as rubbish for their own benefit. Now we know how they are using our DNA we can research ways to put the brakes on it."