Nailing Down Cancer Culprits
Jean Marx
A general sending troops out to battle wants as much intelligence about the enemy and its weaknesses as possible. Researchers fighting cancer hope the complete human genome sequence will help provide such information.
CREDIT: ILLUSTRATION: CAMERON SLAYDEN
The sequence will greatly speed the identification of the genetic underpinnings of cancer. Over the past 15 years or so, researchers have learned that cancers are usually caused by the accumulation of several gene mutations, some of which activate cancer-promoting oncogenes, whereas others inactivate tumor suppressor genes. And though scientists have fingered roughly 100 oncogenes and 30 or so tumor suppressors, that's "only a fraction of the genes that cause cancer," says cancer gene expert Bert Vogelstein of the Johns Hopkins University School of Medicine in Baltimore, Maryland.
In the past, once researchers determined where in the genome a cancer gene resides, they could still spend months, or even years, scouring the region--often a megabase or two long--looking for likely candidate genes to test. Now, Vogelstein says, that can be done "literally with the click of a button. The availability of the sequence enormously simplifies the search for those [missing cancer] genes."
Researchers are also using microarrays and other techniques to measure changes in the expression of thousands of genes at a time--information that provides a very detailed picture of the alterations leading to cancer development and spread. Knowing all the human genes will make this picture more complete. Researchers have already found that tumors that look similar to a pathologist may display different gene expression patterns--and that these differences can reveal potentially lifesaving information about how the cancers will respond to therapy.
