Differences in the quantity of DNA found in the urine and saliva of smokers versus nonsmokers: implications for the timing of epigenetic events.

TP53 is a tumor-suppressor gene coding for p53, a protein responsible for cell-cycle arrest and DNA repair. Smoking has been demonstrated to lead to the methylation of tumor-suppressor genes in noncancerous lung biopsy tissues of smokers, and in bodily fluids, promoter hypermethylation occurs very early in the progression of cancer. Thus, DNA methylation changes may be initiated long before cells become cancerous. As this association has never been explored in young, healthy individuals, we decided to look at DNA isolated from urine and saliva samples taken from young male and female smoking and nonsmoking participants. While p53 methylation was not found in any of the samples tested, differences in DNA concentration between the two groups may shed light on the timing of epigenetic alterations, as well as better explain why the negative impact of smoking is not often found in young, healthy adults.