While we all know that smoking is bad for you, and even your baby, it seems that the effects last longer than you may think. Researchers from Imperial College London investigate and show that while there are epigenomic benefits to giving up smoking, there are also some changes that persist for what seems to be a lifetime.
Previously, several other groups have shown that smoking creates two distinct DNA methylation signatures and that one of the classes can be detected up to a whopping 60 years after quitting.
In this latest study, researchers used the 450K array to capture the dynamics of smoking-induced alterations that revert to non-smoker status following cessation. The group performed their EWAS on blood samples taken from two European female populations (n = 745). Here’s what they found out about the dynamics:
- Confirming previous work, they replicate the observation of two distinct classes of CpGs; some sites remain altered and some sites return to non-smoker status after quitting.
- The sites that remain altered are present even 35 years after quitting.
- The dynamics of the changes after quitting appear to be driven by the “differential and site-specific magnitude” of the alterations.
- Interestingly, these changes don’t correlate with intensity and duration of smoking.
- But the most affected CpGs appear the be the ones that don’t revert after quitting.
- Linking methylation to expression, the group found a general regulatory relationship – that the methylation in this case is repressing gene expression but in remote sites rather than those in expected areas close to the gene.
- Notably, a number of CpGs in LRRN3 are of interest, as it was one of the few genes where methylation and expression were directly associated.
- It was also the only gene that was found to be significantly associated with smoking for both methylation and gene expression levels.
Overall, this study provides an interesting insight into how the epigenome responds to a common and chronic exposure, but also offers up some new biomarkers that could help refine the risk profile associated with smoking and lung cancer.
Learn more about the long-term effects in Human Molecular Genetics, January 2014