Researchers discover genes involved in colorectal cancer

A jumping gene with the fairy tale name "Sleeping Beauty" has helped to unlock vital clues for researchers investigating the genetics of colorectal cancer.

A study published today used the Sleeping Beauty transposon system to profile the repertoire of genes that can drive colorectal cancer, identifying many more than previously thought. Around one third of these genes are mutated in human cancer, which provides strong evidence that they are driver mutations in human tumours.

The collaborative project funded by Cancer Research UK and the Wellcome Trust was led by Dr David Adams from the Wellcome Trust Sanger Institute, and Dr Douglas Winton, of the Cancer Research-UK Cambridge Research Institute.

"These findings, when combined with mutation data from human colon cancers, will drive forward our understanding of the processes that lead to colorectal cancer," says Dr Adams, senior author from the Sanger Institute. "They demonstrate how many genes can contribute to this cancer and how these genes work together in the development of this disease".

The Sleeping Beauty transposon system induces genetic mutations at random, identifying and tagging candidate cancer genes, the drivers that cause colorectal cancer. This system has become critical in uncovering the genetic pathways that cause cancer, and, in this study, the team identify more than 200 genes that can be disrupted in human colorectal cancers.

Colorectal (bowel) cancer is the third most common cancer in the UK, and the second most common cause of cancer deaths after lung cancer; just under 40,000 people were diagnosed with bowel cancer in the UK in 2008 – around 110 people every day – a figure which has shown little improvement over the last decade.

Case Western Reserve University School of Medicine researchers published a study identifying the hereditary components of colorectal cancer (CRC.) It is the first large linkage study of families with CRC and colon polyps in the country.

Because only five percent of CRC cases are due to known gene defects, this study is designed to identify the remaining CRC-related susceptibility genes. The team built on a previous study which identified a specific region on chromosome 9q that harbors a CRC susceptibility gene. Upon review of a whole genome scan of all chromosome pairs in 194 families, the researchers were able to identify additional CRC gene regions on chromosomes 1p, 15q, and 17p.

While the overall Case Western Reserve University School of Medicine study looked at families with colon cancer and colon polyps, the study also analyzed families with different clusters of cancer, such as CRC with multiple polyps and CRC with breast cancer. These different phenotypes appeared to link to different chromosomal regions, which the study teams says supports the idea of multiple susceptibility genes causing different types of cancers. These links will be further investigated in the next phase of the study.