Electronic cigarettes induce DNA strand breaks and cell death independently of nicotine in cell lines

Oral Oncol. 2016 Jan:52:58-65. doi: 10.1016/j.oraloncology.2015.10.018. Epub 2015 Nov 4.


Objectives: Evaluate the cytotoxicity and genotoxicity of short- and long-term e-cigarette vapor exposure on a panel of normal epithelial and head and neck squamous cell carcinoma (HNSCC) cell lines.

Materials and methods: HaCaT, UMSCC10B, and HN30 were treated with nicotine-containing and nicotine-free vapor extract from two popular e-cigarette brands for periods ranging from 48 h to 8 weeks. Cytotoxicity was assessed using Annexin V flow cytometric analysis, trypan blue exclusion, and clonogenic assays. Genotoxicity in the form of DNA strand breaks was quantified using the neutral comet assay and γ-H2AX immunostaining.

Results: E-cigarette-exposed cells showed significantly reduced cell viability and clonogenic survival, along with increased rates of apoptosis and necrosis, regardless of e-cigarette vapor nicotine content. They also exhibited significantly increased comet tail length and accumulation of γ-H2AX foci, demonstrating increased DNA strand breaks.

Conclusion: E-cigarette vapor, both with and without nicotine, is cytotoxic to epithelial cell lines and is a DNA strand break-inducing agent. Further assessment of the potential carcinogenic effects of e-cigarette vapor is urgently needed.

Keywords: DNA damage; Electronic cigarettes; Head and neck squamous cell carcinoma (HNSCC); Nicotine; Oral cancer; Smoking; Strand breaks.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Carcinoma, Squamous Cell / metabolism
  • Cell Death / drug effects
  • Cell Line, Tumor / drug effects*
  • DNA Damage / drug effects*
  • Electronic Nicotine Delivery Systems / adverse effects*
  • Epithelial Cells / drug effects*
  • Head and Neck Neoplasms / metabolism
  • Humans
  • Nicotine / pharmacology*
  • Nicotinic Agonists / pharmacology*
  • Volatilization


  • Nicotinic Agonists
  • Nicotine