Gene insertions common in cancer

Rearrangement of the genome is common in cancer – for example, deletions, rearrangements and inversions. However, little is known about insertions into the genome and the role they play in cancer.

To address this, the EU-funded CANCER INSERTOME (The landscape and functional impact of tumour-specific genomic insertions of 1,000 cancer genomes) initiative studied massive quantities of cancer genome data.

Insertions in the DNA arise from either transposable elements, DNA that can move around the genome, or viruses that insert themselves at random. This process is known as retrotransposition, and this is what researchers searched for.

CANCER INSERTOME found that retrotransposition occurs at least once in about half of all cancers, and more commonly in lung and colorectal cancers. For these cancers, the rates are 93 % and 75 %, respectively.

Researchers also identified a mutation process in cancer cells called L1-mediated 3' transduction, which made up about a quarter of all retrotranspositions studied. Of these, over 2 % involved relocation of entire genes or gene regions.

This project has helped to highlight the importance of retrotransposition in cancer genomics. The understanding generated by this project will help cancer biologists fight the disease in the long term.