Margaret J. Kovach, PhD

.....Marketed as a safer alternative to tobacco products, the popularity of e-cigarette use is on the rise. However, little is known about the potential health risks associated with their use. Many e-cigarette filling solutions are known to contain significant levels of tobacco alkaloids, including nicotine, anabasine, myosmine and cotinine. Using a panel of lung cell cultures distinguished by differences in sex and disease status, this study addresses the in vitro effects of common tobacco alkaloids found in e-cigarettes on cell proliferation and gene expression. We hypothesize that alkaloid exposure of lung cells is associated with abnormal proliferation and gene expression, and predict that cellular response to the alkaloids will present in a sex-specific manner. Alkaloid exposure on each lung cell line was evaluated at 1 µg/mL, 10 µg/mL, and 100 µg/mL concentrations throughout a 10-day time course. Cellular proliferation was measured daily using the CellTiter-Glo® Luminescent Viability Assay, and RNA isolated after 48 and 96-hour time points for gene expression analysis of 10 cancer biomarkers by qRT-PCR. Findings indicate anabasine and myosmine display a significant (p<0.05) inhibitory effect on cellular proliferation and gene expression, whereas the effect of cotinine and nicotine was minimal. Each cell line had an inherent, characteristic pattern of cellular proliferation in response to alkaloid exposure. Notably, the cancer cell line demonstrated more variability among replicates, which we attribute to the non-clonal nature of this cell line, and the female cell line displayed increased susceptibility to toxicity by the higher alkaloid concentrations. Significant differences in gene expression (p<0.05) were noted for AHR, CEACAM6, CYP1A1, MDM2, TP53, ALDH3A1 and GPX2. Correlation of abnormal patterns of cell proliferation and differential gene expression with risk for disease are discussed.