Some of them are only temporarily turned on or off, while other changes are permanent.
Smoking temporarily and permanently activates and deactivates certain genes including ones for fighting lung cancer and DNA repair, according to researchers from the BC Cancer Agency.
The team took samples from the lungs of 24 current and former smokers as well as from people who have never smoked. Using serial analysis of gene expression, they created libraries to identify patterns of gene activity.
The researchers found changes that were irreversible and some changes that were reversed by stopping smoking. They report that the reversible genes were particularly involved in xenobiotic functions, nucleotide metabolism, and mucus secretion. Also, some DNA repair genes are irreversibly damaged, and smoking also switched off genes that help combat lung cancer development, according to the scientists.
The investigators say that they identified a number of genes not previously associated with smoking that are switched on in active smokers. An example is CABYR, a gene involved in helping sperm to swim and associated with brain tumors, which may have a ciliary function.
The team also further investigated changes in genes involved in airway repair and regeneration. Within this group, they identified genes that fell into three categories following cessation of smoking: reversible (TFF3, encoding a structural component of mucus; CABYR, in it’s newly discovered bronchial role), partially reversible (MUC5AC, a mucin gene), and irreversible (GSK3B, involved in COX2 regulation). These findings were tested against a second cohort of current and former smokers and nonsmokers.
The study was published on August 29 in BMC Genomics.