More cancer genes lurking beneath

There is growing evidence to show more genes may be responsible in causing cancer growth than previously anticipated. In a recent study by the scientists of the Cancer Genome Project at the Wellcome Trust Sanger Institute in Cambridge, England, the genetic patterns associated with cancer had been investigated. The results were published in the recent issue of Nature.

P. Andrew Futreal, Ph.D, co-leader of the project said scientists knew for long the role played by genetic predisposition in cancer but they were quite surprised to note the abundant number of rogue genes implicated.

Cancers result from accumulated mutations in the 30,000 genes in the human genome. These mutations cause a cell to multiply uncontrollably to form a tumor that could then spread to other parts of the body.

So far, scientists had identified about 350 genes that could lead to development of different cancers, but there was no clear knowledge on the number of mutations in these genes that were directly involved in triggering cancer.

Futreal and his team screened the DNA from 210 human cancers and from healthy human tissue. At the core of the study was the evaluation of 518 genes that make a type of protein linked to various cancers.

The results were quite interesting. The team found no mutations in 73 out of the 210 cancers and the others showed significantly high number of mutations; as high as more than 1000 gene mutations.

Out of the above many do not affect cancer development and such mutations are ‘passenger mutations’.

But, there were also an estimated 158 driver mutations that increase cancer risk. Of the 518 genes, nearly 120 had driver mutations. Thus, the composition of driver mutations in the cancer genes is naturally very high.

Futreal said a large number of mutations in cancers are passengers but the driver mutations are significant in terms of proportion and therefore, more genes could be responsible for cancer development than previously believed.

The study has paved the way for development of specifically targeted treatment. Mark Wallport of the Wellcome Trust said the understanding of cancer mutations in genes would be crucial in developing accurately targeted treatments. Knowledge of the gene mutations would help in developing new drugs that would attack the specific genetic errors. For example, the drug Glivec that is used to treat chronic myeloid leukemia, has been developed to target an aberrant form of a protein called tyrosine kinase. Glivec blocks uncontrolled cell proliferation and prevents the further growth of cancer.