The study team, led by researchers from the Netherlands Cancer Institute (NKI) and from the Wellcome Trust Sanger Institute, analysed the DNA of more than 500 lymphomas to find the cancer causing mutations. They discovered just over 10,000 mutations overall, which together implicate almost 350 regions in the mouse genome in cancer formation. Fifty of these regions correspond to genes known to be involved in human cancers while the other regions were novel, which may add to our existing knowledge of cancers.

The researchers used a virus, called the murine leukaemia virus, to produce mutations in cancer genes. This virus mainly aims at white blood cells, resulting in lymphoma, a common tumour of the blood system. "Human cancers are generally thought to be formed by the stepwise accumulation of mutations that disrupt genes within a cell, and the virus mimics this process as it inserts itself into the mouse genome. The virus then acts as a 'tag', allowing us to identify where it has integrated and which gene or genes have been disrupted," explained Dr David Adams, senior author on the paper.

"By finding an average of 20 mutations from each of the 500 tumours, not only did we find many new cancer genes, but we can see which genes work together in the same cell to transform it into a lymphoma," said Dr Jaap Kool, one of the authors of the paper. They discovered that the infected mouse lines had mutations in genes called p53 and p19, which are known to suppress the development of cancer and belong to the most commonly mutated genes in human cancers.