Cancer cells mutate quickly, enabling them to outsmart medicines and survive inhospitable conditions in the body. Scientists have generally thought that the rapid cell division in tumors is to blame, with the changes resulting from errors that cells copy their DNA. But it now appears that the colon cancer cells, at least in a petri dish, have a different way to stimulate their mutation rate, they can simply move in response to unfavorable conditions. The mechanism behind the dramatic increase, reported in tomorrow's issue of Science *, is a mystery.
Mark Meuth, a molecular geneticist at the University of Utah, Salt Lake City, was intrigued by an exception to the rule of rapid change in cancer cells: a cell line cancer human colon that when grown in a dish transferred to the same low rate as noncancerous cells. This was particularly surprising because the cell line, called 2774, has a defective DNA repair mechanisms; other cells with this defect quickly accumulate mutations.
mutation rate rose, however, when Burt Richards, a scientist in the laboratory Meuth, accidentally left a dish of tumor cells to invade. When the cells left boxes team crowded for 2 weeks, they found that a mutated gene, called HPRT , had transferred 700 times faster than in cells grown at low density, even if the cells are not crowded division. Another cell line, also colon cancer and called SK-UT-1, has strengthened its HPRT mutation rates 34 times after reaching a high concentration of cells.
Meuth said he does not know why the overcrowded cells mutate so easily, but he suspects that an unfavorable environment around the cells, such as lack of nutrients or oxygen in cramped conditions, password somehow a mutation mechanism. Lawrence Loeb, a pathologist at the University of Washington, Seattle, said that if researchers can discover the mutation rate mechanism has increased, it could provide a new avenue of treatment for any cancer cell that uses it. "If the increase is due to something simple like oxygen free radicals, antioxidants we could give," he said.
* For details, Science Online subscribers can link to the full report.
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