Genes Linked To Melanoma Growth

Vermont State Trooper Joshua Lemieux conducts search on Plains Road in Jericho, Vt., Thursday, Oct. 12, 2006, looking for any clues related to the disappearance of University of Vermont student Michelle Gardner-Quinn. Gardner-Quinn, 21, of Arlington, Va., was last seen Saturday at 2:34 a.m. walking back to the University of Vermont campus on Main Street in Burlington after a night out downtown with friends. (AP Photo/Burlington Free Press, Alison Redlich) AP/Burlington Free Press, A Redlich

Working independently, two research teams have linked groups of genes to the rapid spread of melanoma, the deadliest form of skin cancer. It is one of the first apparent breakthroughs resulting from the mapping of the human genome.

Their work could eventually help doctors quickly diagnose melanoma and treat individual patients based on their genetic makeup.

The same principle may apply to other cancers as well.

The studies were conducted at the National Human Genome Research Institute in Bethesda, Md., and at the Massachusetts Institute of Technology.

In both studies, researchers identified a set of genes that is active in highly invasive growths. Some genes were common to both studies.

"For 100 years we've looked at melanomas through the lens of a microscope, and wondered how tumors that looked so similar can act so different. Now we've used the lens of genetics," said Jeffrey Trent, a senior researcher at the National Human Genome Research Institute.

Both groups used a technique called gene expression profiling, in which glass slides holding thousands of bits of DNA are exposed to genetic material from tumor cells, and byproducts of the cells' genes stick to the DNA on the slide.

The technique tells which genes are "switched on," or active, in the tumor cells, and how active they are.

Trent's team found up to 200 genes associated with highly invasive melanoma cells.

The second study group, led by scientists at the Massachusetts Institute of Technology, narrowed down their invasive set of genes to just 32.

They went on to test one of them, known as RhoC, in mice to see if it can make melanomas more invasive. They found that the most benign melanomas became 50 times more invasive with the active gene, MIT cell biologist Richard Hynes said. Highly invasive growths became 80 percent less so when the gene was blocked.

The findings will be published this week in the journal Nature.

Hynes said the work will help lead to genetic tests that could identify which patients are most at risk, and help researchers identify new targets for therapies focusing on the most malignant tumors.

Melanoma is now the most deadly form of cancer in young people between the ages of 25 and 29. Excessive exposure to the sun's harmful UVA and UBV rays can damage DNA in the skin and increase the risk of developing the disease.

"We've known for decades that melanoma is less aggressive in some patients and more aggressive in others, but we haven't known why," Trent, of the Maryland institute, said in a statement.



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