Vaping and gene expression are now firmly linked in the scientific evidence base. A landmark study published in Frontiers in Oncology in June 2026 found that regular vapers show altered activity across 3,124 genes. That is a striking number. But the bigger story is what drives those changes.

It is not simply how much or how often someone vapes. The type of flavours and devices used matters far more than many people realise.

How Vaping and Gene Expression Were Studied

Researchers at the Keck School of Medicine at the University of Southern California recruited 83 participants: 35 vapers, 24 cigarette smokers and 24 non-users. They collected cells from the inner cheek of each participant. Using RNA sequencing, the team examined gene activity across the entire genome at once.

Researchers adjusted all findings for age and sex. Vapers showed changes across 3,124 genes. The activity of 71.6% of those genes fell below normal, while 28.4% rose above it. Smokers showed changes across 2,180 genes. Both groups shared some disrupted pathways. But 60.1% of the gene changes in vapers did not appear in smokers at all. Vaping appears to trigger its own distinct biological effects, separate from those tobacco combustion causes.

Flavours and Devices Drive Vaping and Gene Expression Changes

This is where the research gets particularly important. When the team examined vaping dose, only 27.6% of the altered genes showed a consistent response across all dose measures. Product characteristics told a different story. Device type and e-liquid flavour together explained 66.6% of the gene changes researchers recorded.

The flavour breakdown was striking:

Fruit flavours correlated with changes in 31% of affected genes. Multiple flavours together correlated with changes in 64.3% of affected genes. Sweet flavours accounted for 2.9%. Mint and menthol accounted for just 0.9%.

Device generation mattered too. Users of third-generation devices, commonly called mods, showed the strongest and most consistent changes. So did vapers who combined multiple device types. Earlier devices produced fewer detectable effects, though smaller sample sizes in those groups may have limited the analysis.

Senior author Professor Ahmad Besaratinia was direct: each flavour has unique chemical attributes that produce different biological effects. Regulators, he said, need to weigh this carefully when assessing the health risks of individual flavoured products.

Cancer Pathways and Gene Regulation in E-Cigarette Users

The team ran a detailed functional analysis on the altered gene lists. Cancer ranked as the top disease category in both groups. Among vapers, 90.8% of the identified genes with a known function connected to cancer pathways. Among smokers, the figure was 92.8%.

The RHO GTPase cycle was the most disrupted pathway in both vapers and smokers. This pathway controls cell migration, division and adhesion, all processes central to how cancer invades and spreads. The study also found shared disruptions to DNA replication, cell cycle checkpoints and chromosome segregation. These point to cells trying to slow down and protect genomic stability after exposure.

E-cigarette use and gene regulation linked to ciliogenesis also emerged as a concern unique to vapers. Cilia are tiny structures that line the airways and help clear inhaled particles. When ciliogenesis goes wrong, it can mark an early step toward cancer. Cancer regulators p53 and KRAS appeared as likely upstream drivers of the gene changes in both groups.

Vaping and Gene Expression: Why the Science Matters

Chronic diseases take decades to develop. Scientists therefore look to early molecular signals as the clearest window into future risk. Vaping and gene expression research fills exactly that role. The mouth is the first tissue to contact inhaled aerosol. That makes oral cells a sensitive and biologically relevant place to detect early harm.

This study is among the first to test how vaping dose, device type and flavour each contribute to biological changes independently. The evidence shows that dose alone does not explain what researchers observed. Product design and chemical composition both add their own layer of harm. You cannot fully characterise e-cigarette exposure without accounting for all three.

The research has a direct message for regulators. Professor Besaratinia noted that regulators must weigh the benefits of e-cigarettes for adult smokers against the risks they pose. This study shows that flavoured products produce disease-related molecular changes regardless of the user’s age.

What Researchers Are Doing Next on Vaping and Gene Expression

The USC team now focuses on the specific chemicals in vaping liquids to find which compounds drive the gene expression changes. Once researchers identify those compounds, policymakers can direct manufacturers to remove or reduce them. The raw RNA sequencing data sits in the public Gene Expression Omnibus repository under accession number GSE330022. It is open to the broader scientific community to build on.

Source: dbrecoveryresources