Abstract 4470: E-cigarette aerosol exposure increases NF-kB and modulates inflammatory markers in oral epithelial cells

Abstract

Abstract Background: E-cigarette use has skyrocketed among youth, in part because e-cigarettes are perceived as a safer substitute for traditional cigarettes. However, the resulting health effects of e-cigarette use are still unclear. E-cigarette aerosols contain harmful and potentially harmful substances such as flavorings, carbonyl compounds, heavy metals, carcinogens and reactive oxygen species (ROS). A recent in vitro study from our laboratory showed that e-cigarette aerosols can increase cellular ROS and suppress cellular antioxidant capacity. An imbalance between the ROS production and the availability of antioxidants or free radical scavengers, can lead to chronic inflammation. Here we examine the effect of exposure to e-cigarette aerosols on the expression of the inflammatory regulator NF-kB and its downstream inflammatory targets in oral epithelial cells. Methods: Human oral epithelial cancer (UM-SCC-1) cells were exposed, every other day for 2 weeks, to e-cigarette aerosol extracts (18 mg/ml of nicotine; tobacco flavor) prepared from two distinct e-cigarette brands. Standard tobacco extracts were used as a positive control. Whole-cell RNA was isolated and processed for RNA-sequencing. The altered gene expression was further validated by western blotting and ELISA using a human cytokine array. Data were analyzed by Student's t-test. Results: RNA sequencing data showed that a 2-week exposure of oral epithelial cells to e-cigarette aerosol extracts resulted in significant changes in several key cellular signaling pathways, including inflammatory and immune response signals. Exposure to e-cigarette aerosol extracts resulted in a significant increase in the expression of proteins involved in inflammatory pathways, such as TLR3, TGF beta, ERK1/2 and NF-kB. We also observed a significant increase in pro-inflammatory and anti-inflammatory cytokines after exposure to e-cigarette aerosol extracts, including CD54, IL-1a and IL-10. Conclusion: Our data suggest that chronic exposure to e-cigarette aerosol increases the expression of TLR3, TGF beta, and ERK1/2, which possibly contributed to the observed increase in NF-kB and its down-stream targets (e.g., CD54, IL-1a and IL-10). NF-kB is a pleiotropic transcription factor with key roles in multiple biological processes, such as immune homeostasis and development. Chronic NF-kB activation by e-cigarette aerosol exposure could contribute to chronic inflammation and tumorigenesis. Citation Format: Vengatesh Ganapathy, Jimmy Manyanga, Dehra McGuire, Daniel Brobst, Balaji Sadhasivam, Mayilvanan Chinnaiyan, Constantin Georgescu, Jonathan Wren, Lurdes Queimado. E-cigarette aerosol exposure increases NF-kB and modulates inflammatory markers in oral epithelial cells. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4470.