E-Cigarette vaping regulates genes involved in DNA damage and cancer: a pilot study in humans

There is a paucity of data on how human vaping behaviors modifies E-Cigarette (E-cig) exposures, making it difficult to assess the associated risk. This pilot study aimed to investigate the toxicity of e-cigs to humans by investigating changes in DNA damage-response genes in buccal and blood samples. Samples from three subjects (2 Males and 1 Female) were evaluated using RT-qPCR. Each subject made three visits to the lab (nTOT=9 visits); buccal and blood samples were collected before and after scripted vaping 20 puffs (nTOT=18 samples); vaping topography data were collected in each session. Subjects used their own e-cig containing 50:50 Propylene Glycol (PG): Vegetable Glycerine (VG)+(3-6) mg/ml nicotine. After exposure, the tumor suppressor TP53 was significantly (p<0.05) upregulated in buccal samples which was accompanied by changes in other DNA damage and repair genes. TP53 expression was puff volume and flow rate dependent in both tissues. In blood, the significant downregulation of N-methylpurine DNA glycosylase (MPG), a base excision repair gene, was consistent across all subjects. Ingenuity Pathway Analysis (IPA) showed that DNA repair and cell cycle pathways were the most enriched pathways after e-cig exposure in buccal swab samples. In blood, DNA repair and cancer were the most dominant pathways. This is the first study to demonstrate that vaping 20 puffs significantly alters expression of TP53 along with several other DNA damage genes in human tissues; vaping behavior is an important modifier of this response. A larger study is needed to confirm these relationships.