Gene Patterns Remain Skewed After Quitting Smoking
Date: 22-Jun-04
Country: USA
Dr. Avrum Spira from Boston University School of Medicine and colleagues identified genes normally expressed in airway cells, and then looked at how gene expression changed with cigarette smoking and whether changes were reversible when smoking was discontinued.
In people who were currently smokers, 97 genes were expressed differently than in people who had never smoked, according to the results reported in the Proceedings of the National Academy of Sciences.
People who had stopped smoking at least two years before the study tended to have gene patterns that resembled those seen in people who had never smoked, and more recent quitters tended to resemble current smokers.
Thirteen genes did not return to normal levels in former smokers even after 20 to 30 years of smoking cessation, the investigators found.
Among these genes were a number of potential tumor suppressor genes that were permanently decreased, and several cancer-related "oncogenes" that were permanently increased.
The persistently abnormal gene expression may provide growth advantages to certain cells, allowing for "perpetuation of these cells years after smoking had been discontinued," the authors suggest. "These permanent changes might explain the persistent risk of lung cancer in former smokers."
Also, the team points out, the findings "raise the possibility that the airway gene expression profile in smokers may serve as a biomarker for lung cancer." In other words, genetic testing of airway cells might show who is likely to develop cancer.
SOURCE: PNAS, June 21 Early Edition, 2004.