Abstract 502: Electronic cigarette aerosols increase cellular reactive oxygen species and induce significant oxidative DNA damage
Authors: Ganapathy Vengatesh , Manyanga Jimmy , McGuire Dehra , Brobst Daniel , Wagener Theodore , Rubenstein David , Ramachandran Ilangovan , Queimado Lurdes 
Published: July 2017

Background: E-cigarettes (ECs), also known as electronic nicotine delivery systems (ENDS) are battery-operated devices that deliver nicotine through inhaled aerosols. The health risks associated with EC use are unclear, but ECs have been promoted as a safer alternative to tobacco smoking and a smoking cessation aid. Currently, more than 13% of American high school students and 10% adults report using ECs. EC aerosols contain unique constituents (e.g. silicate beads, tin and flavorants), as well as other toxicants also present in tobacco smoke, including carcinogens and reactive oxygen species (ROS). The potential of EC aerosols to induce DNA damage has not been fully characterized.

Aims: (1) To examine the effects of EC aerosol exposure in the levels of cellular reactive oxygen species (ROS); and (2) To evaluate the potential of EC aerosols to cause oxidative DNA damage.

Methods: EC aerosols and mainstream smoke extracts were generated from distinct brands of ECs containing diverse nicotine concentrations and a reference combustible cigarette, in controlled conditions using a modified smoking apparatus. Human normal epithelial and oral cancer cell lines were exposed up to 2 weeks to diverse doses of EC aerosol extracts equivalent to 1 to 100 EC puffs. Levels of ROS were evaluated using the 2’,7’ -dichlorofluorescin diacetate (DCFDA) cellular ROS detection assay kit (Abcam). Overall DNA damage was quantified using two distinct assays q-PADDA and Comet assay. 8-Oxoguanine, one of the most common DNA lesions resulting from ROS, was quantified using a commercially available ELISA kit. Data were analyzed by Student’s t-test.

Results: Exposure to EC aerosols caused a significant increase in ROS levels. Exposure to EC extracts induce significant DNA damage measurable by q-PADDA and Comet assay. Overall, EC aerosol extracts induced significantly less DNA damage than mainstream smoke extracts. Yet, a significant increase in 8-oxoguanine lesions was observed after acute and long-term exposure to EC extracts compared to the control.

Conclusion: Both short- and long-term exposure to EC aerosols can increase cellular ROS levels and cause significant DNA damage. Moreover, EC aerosols cause oxidative DNA lesions which are highly mutagenic, and can lead to tumor initiation and progression. Our study emphasizes the urgent need to further investigate the potential short- and long-term health effects of EC aerosols.

Grant support: This work was supported by the Oklahoma Tobacco Research Center (LQ). Dr. Queimado holds a Presbyterian Health Foundation Endowed Chair in Otorhinolaryngology.

Citation Format: Vengatesh Ganapathy, Jimmy Manyanga, Dehra McGuire, Daniel Brobst, Theodore Wagener, David Rubenstein, Ilangovan Ramachandran, Lurdes Queimado. Electronic cigarette aerosols increase cellular reactive oxygen species and induce significant oxidative DNA damage [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 502. doi:10.1158/1538-7445.AM2017-502