Researchers at the Keck School of Medicine of the University of Southern California (USC) have discovered that molecular changes in DNA observed in smokers are also found in vapers. The study outlining their findings is published in Epigenetics.
Our inherited DNA code is subject to chemical modifications which can impact whether genes are effectively turned "on" or "off". These chemical modifications are known as epigenetic changes. They can often be a part of normal development or they can result from external and environmental factors, such as lifestyle choices.
A variety of eloquent analogies exist to simplify the complex biological phenomenon of epigenetics. A personal favorite is the likening of epigenetics to a musician playing the piano.
The DNA code that we inherit from our parents represents the note sheet for a piece of music. For the music to be played, a pianist is required. No two musicians are the same; each will possess their own unique style and approach for playing the same sheet of music. In biology, the pianist represents the epigenetic processes that effectively "play out" the inherited DNA code.
One such lifestyle choice is the decision to smoke cigarettes. A plethora of studies have demonstrated that smoking can cause epigenetic changes linked to the development of cancer.
Now, a team of scientists from the Keck School of Medicine of USC have demonstrated that vaping, an alternative to smoking often perceived as being "less harmful", can also induce similar epigenetic effects.
Vaping linked with chemical modifications to DNA
The research was led by Ahmad Besaratinia, PhD, associate professor at the Keck School of Medicine of USC and examined the association between vaping and epigenetic changes in a sample of 45 individuals matched for age, gender and race.
The sample were divided into three categories: vapers, smokers and a control group of people who did not vape or smoke.
In order to measure epigenetic changes, the scientists quantified DNA methylation levels in a specific DNA sequence known as Long Interspersed Nucleotide Element 1 (LINE-1), and global DNA hydroxymethylation (5-hmC) levels. These are chemical modifications known to impact gene activity and can occur in both healthy and diseased states.
Blood was taken from each of the participants from the three groups and analyzed to detect these epigenetic changes. The results show that, from the 45 participants, vapers and smokers demonstrate significant reduction in the levels of both chemical tags when compared to the control group.
"That doesn't mean that these people are going to develop cancer," says Besaratinia. "But what we are seeing is that the same changes in chemical tags detectable in tumors from cancer patients are also found in people who vape or smoke, presumably due to exposure to cancer-causing chemicals present in cigarette smoke and, generally at much lower levels, in electronic cigarettes' vapor."
Whilst a growing amount of work is emphasizing the health concerns associated with vaping, this study is the first to show that vapers possess these biologically relevant chemical changes in their blood cells.
"Our new study adds an important piece to that puzzle by demonstrating that epigenetic mechanisms, specifically changes in chemical tags attached to the DNA, may contribute to the abnormal expression of genes in vapers and smokers alike," said Besaratinia.
Besaratinia and colleagues will continue their research, with their next steps being an exploration into the entire genome to identify genes that are targeted by these two chemical changes in vapers.
He concludes: "The epidemic of teen vaping and the recent outbreak of vaping-related severe lung injury and deaths in the U.S. underscore the importance of generating scientific evidence on which future regulations for electronic cigarette manufacturing, marketing, and distribution can be based."
1. Caliri, Caceres, Tommasi and Besaratinia. (2020). Hypomethylation of LINE-1 repeat elements and global loss of DNA hydroxymethylation in vapers and smokers. Epigenetics. DOI: 10.1080/15592294.2020.1724401.