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17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
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How Free Radicals Abet a Cancer rascal
14 March 1997 (All day)
When a waiter suggests the salad bar, there is a good reason to load up on the greens: They're full of antioxidants thought to sop up free radicals, corrosive molecules that already had a bad reputation because they can damage DNA and perhaps lead to cancer. Now researchers report in today's issue of Science* that one kind of free radical also helps a protein called Ras transmit a signal that stimulates normal cell growth and--when it goes haywire--sparks the uncontrolled cell division leading to cancer.
Ras sends its growth-stimulating message to the nucleus through superoxide, as well as through the MAP kinases (MAPK and MAPKK).
A team led by Pascal Goldschmidt-Clermont, a cardiologist at Ohio State University in Columbus, measured the levels of superoxide--a free radical made of an oxygen molecule with an extra electron--in cultured mouse cells. Team members found that cells with a mutated ras gene--one that causes the cell-division pathway to get stuck in the "on" position--produce more superoxide than do cells with the normal ras gene. Chemically blocking the pathway sharply reduced superoxide concentrations. When the team treated cells to produce less superoxide in response to Ras, the DNA replication during cell division abated, suggesting that superoxide stimulates DNA synthesis.
Other experts are intrigued by the finding. Roger Davis, a cell biologist at the University of Massachusetts Medical Center in Worcester, predicts that linking oxygen free radicals to Ras-activated growth "will cause a lot of people to rethink the mechanisms of growth control." What's more, says cell biologist Marc Symons of Onyx Pharmaceuticals in Richmond, California, because the Ras pathway can spur tumor growth, "the elements in [this] pathway are all good [anticancer] drug targets."