Figure 1 from Cigarette Smoking and E-cigarette Use Induce Shared DNA Methylation Changes Linked to Carcinogenesis

General overview of the study and identification of cell type–specific smoking-dependent epigenetic changes. A, Overview of the study. We aimed to identify cell- and tissue-specific epigenetic alterations and used a discovery set of buccal, cervical, and immune cells (all female). Findings were then validated in several independent sets to confirm the association with current and former smoking and explore association of cell-specific effects across smoking alternatives (e-cigarette use, moist tobacco use), lung cancer tissue and progression, and possibility to predict lung cancers in smokers using noninvasive samples. A detailed workflow of the analysis is shown in Supplementary Fig. S1. B, Scatterplots of methylation beta values in three CpGs located in the AHRR gene or intergenic region versus immune cell proportion (buccal and cervical samples) or lymphoid proportion (blood) indicate methylation differences may be derived from distinct cell types. C, Visualization of delta-beta values across four groups of CpGs identified in Supplementary Fig. S5A. A matrix of inferred delta-beta values across all tissues for all significant CpGs (i.e., significant in at least one tissue in the EWAS) was clustered using UMAP and the following clusters identified: epithelial hypomethylation (epithelial hypoM), immune hypomethylation (immune hypoM), distal epithelial hypermethylation (distal epithelial hyperM; effects in distal epithelium but not directly exposed epithelium), and proximal epithelial hypermethylation (proximal epithelial hypoM; effects in buccal/directly exposed samples only). (A, Created with BioRender.com.)