Monday, December 10, 2007

Scientists discover how BRCA1 gene causes breast cancer

Scientists discover how BRCA1 gene causes cancer

Source: Reuters
Summary: Medical Discoveries
Published: Sunday, December 09, 2007
Study Source: Dr. Ramon Parsons, Columbia University Medical Center, New York

CHICAGO (Reuters) - Mutations in the BRCA1 breast cancer gene appear to be linked with the loss of a protein important for putting the brakes on cell growth, a finding that could lead to new therapies, researchers said on Sunday... Researchers at Columbia, working with at team at Sweden's Lund University, now believe mutations in the BRCA1 gene can leave cells incapable of repairing routine DNA damage. When such damage occurs in a protein called PTEN, which regulates the growth of cells, cell growth is unchecked and tumors form. Women with faulty copies of BRCA1 or BRCA2 have a 50 to 85 percent chance of getting breast cancer. Mutations in these genes account for 5 to 10 percent of breast cancer cases. Most breast tumors are called estrogen-receptor positive, because they are fuelled by the hormone estrogen. About 20 percent are HER2-positive, because a protein called HER2 is involved. A third type is driven by the hormone progesterone.

"When it is mutated, it is no longer present in a cell. If a cut occurs in PTEN, there is no way for this cell to fix it," said Parsons, whose study was published in Nature Genetics. "It is like cutting the brake cable on a car," he said. "If PTEN is broken, you turn on a pathway that tells the cell to grow. It tells the cell to start dividing. It tells the cell, 'don't die."'

Parsons said loss of the protein PTEN is how breast cancer gets started in women who have inherited the BRCA1 gene mutation.

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