The study found that while some cells nonetheless rally and are able to fix their damaged DNA, many others become unable to access their own cellular first aid kit. If they survive long enough to divide and multiply, they pass along their mutations, acquiring malignant properties.
Past research has been controversial. Most studies had focused on just one single chemical component of tobacco. In the UF study, researchers instead used a tar that contains all of the 4,000 chemicals found in cigarette smoke.
“We are now describing how cigarette smoke condensate, which is a surrogate for cigarette smoke, can cause DNA damage and can block the DNA repair of a cell or compromise the DNA repair capacity of a cell. That can be detrimental for the cell and can lead to transformation or carcinogenesis,” said Satya Narayan, Ph.D., an associate professor of anatomy and cell biology at UF's College of Medicine
In their study, the researchers exposed normal breast epithelial cells to cigarette smoke condensate - a tar derived from a machine that literally "smokes" a cigarette in the laboratory - and found the cells acquired mutations characteristic of malignant cells.
The scientists say DNA repair appears to be compromised when chemical components of smoke activate a key gene. That gene interacts with an enzyme that plays a crucial role in repairing damaged DNA, preventing it from doing its job. The cell, despite its mutated form, can then multiply wildly.
A cell with damaged DNA has one of two fates, said Narayan. "Its DNA repair machinery can be enhanced and it can fix the damaged DNA and restore genomic stability, or if the DNA repair machinery becomes compromised within the cell, then it can lead to an accumulation of mutations because the DNA is not fixed before the cell begins to divide. The mutation then becomes a permanent part of the genome and causes genomic instability."
MEDICA.de; Source: University of Florida