Deleting cancer genes

Scientists are constantly on the lookout for genes that cause cancer, the killer disease of our times that is estimated to affect one in three people. Research conducted at the Wellcome Trust Sanger Institute in Cambridge has revealed a new twist to the story of how cancer develops. Instead of focusing on which genes are implicated, the question seems to rather be where the genes are located.

The current study was led by Professor Michael Stratton, the co-leader of the Cancer Genome Project. In fact, it was only last December that the Stratton group was in headlines previously, with the report that they had managed to crack the ‘entire genetic code’ of the two most common types of cancer. Our current understanding of how cancers develop involves the deletion or mutation of genes, so that cells cannot maintain normal functions. Stratton’s group have found that in skin and lung cancers, in fact a whopping 20-30 000 genes are mutated.

The most recent study, published just two weeks ago, aimed to investigate “unexplained” gene deletions that have been observed in cancers. It was found that these genes are located in inherently weak regions of DNA. The DNA molecule consists of an intertwined double helix which is itself looped around proteins called histones. Because of all the twisting and turning going on, it’s easy to see how the molecule might get a bit worn out in some bends. In fact, in ‘weak’ locations, breakages of the DNA molecule can occur, and now researchers suggest that this is the reason why there are so many different genes implicated in cancer.

The problem is that such ‘weak’ bits of DNA, is where we often find genes that protect the cell from becoming cancerous. When these regions with protective genes are broken, the cell tries to ‘tidy up’ the damaged DNA by snipping out these essential regions, and the disease develops.

The researchers also found that cancer cells are much more resilient than we thought, compared to healthy cells. Deletion of a whole 11 percent of its genes went unnoticed by the cancer cells, while in healthy cells, anything over 2 percent results in cell death. The fact that cancer cells are so resistant to gene deletion contributes to the difficulty in designing treatments that target and kill these cells.

By focusing future cancer genomics research into such vulnerable regions of DNA, we can gain invaluable insights into how cancer develops.

This article was published in Student Direct on the 1st of March 2010, and can be viewed at www.student-direct.co.uk here.