Abstract 1465: Studying Basal Cell Adaptation in the Airways in Response to Chronic Tobacco Exposure

Abstract Premalignant lesions in the airways are preceded by the accumulation of cells with a high mutational load, many of which carry driver mutations. Our previous work suggests this is a dynamic process: tobacco smoking increases the size of mutated clones, which contain shorter telomeres and higher Ki67, while smoking cessation appears to be associated with the expansion of clones with near-normal mutational burden and an overall reduction in Ki-67 expression. To understand how these long-term changes take place, we have performed ex vivo functional assays to quantify the competitive advantage imparted by smoke. We have then explored the transcriptomic landscape of these cultures to determine how differential smoke exposure modulates epithelial cell dynamics before and after smoking cessation. Primary basal cells from bronchial explants were co-cultured following different regimes of exposure to cigarette smoke extract (CSE). We find that, upon acute exposure, pre-exposed cells have a ~20% higher chance of proliferating per week than smoke-naïve cells. To test this in a more physiological model, long-term epithelioid cultures were established with chronic exposure to low-dose CSE for months. As before, we observe that over time, pre-exposed cells outcompete the smoke-naïve, suggesting that smoke imparts a beneficial adaptation on re-exposed cells even at low doses. To elucidate this mechanism, we performed RNA sequencing of 48 different combinations of acute and chronic exposure to CSE. Genes were classified into distinct modules according to their regulation following exposure, re-exposure and cessation. Differential expression analysis and gene set enrichment analysis showed that metabolic pathways, including both nutrient and detoxification pathways, are predominantly enriched in these modules. In particular, following cessation, cells with the highest cumulative exposure to CSE displayed senescent-like features which are suppressed with chronic re-exposure. Further analysis and in vivo validation of these results will help elucidate how these changes affect the likelihood of premalignancy and may provide valuable targets for cancer prevention. Citation Format: David Osuna de la Peña, Zornitsa Stoichkova, Moritz Jakob Przybilla, Charlotte Percival, Sarah E. Clarke, Kate H. Gowers, Peter J. Campbell, Sam M. Janes. Studying basal cell adaptation in the airways in response to chronic tobacco exposure [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1465.