Study Reveals Smoking's Link to Breast Cancer

Carcinogens weaken cells' ability to repair DNA, researchers say

FRIDAY, Aug. 25, 2006 (HealthDay News) -- Smoking causes normal breast cells to become cancerous by impairing their ability to repair their damaged DNA, U.S. researchers report.

In laboratory tests, researchers at the University of Florida (UF) exposed breast epithelial cells to cigarette smoke condensate -- a tar gathered from a machine that that artificially "smokes" a cigarette.

When exposed to this tar -- which contains all 4,000 chemicals found in cigarette smoke -- the breast cells developed mutations characteristic of malignant cells.

DNA repair in the breast cells appears to be blocked when chemical components of the smoke activate a particular gene. This gene activity, in turn, interferes with an enzyme that plays a critical role in repairing damage to a cell's DNA, the study said.

If cells with damaged DNA survive long enough to divide and multiply, they can pass along their mutations to new cells, which can then become cancerous.

"Some of these cells that survive are really acquiring true mutagenic characteristics," researcher Satya Narayan, associate professor of anatomy and cell biology at UF's College of Medicine, said in a prepared statement.

"A defect in only one cell is important for growth of a full-blown tumor. You don't need 1,000 or one million cells to be affected. Only a single cell which may have genomic instability due to compromised DNA repair capacity of the cell can be sufficient for a tumor to develop," Narayan said.

The next step for the researchers is to attempt to find ways to manipulate cellular DNA repair and to prevent tumor formation.

The study is published in the current issue of Oncogene.

More information

The U.S. National Cancer Institute has more about smoking and cancer.

SOURCE: University of Florida, news release, August 2006
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