Chip-seq analysis of H3K4me3, H3K27me3, DNMT1 and EZH2 binding to chromatin following acute (10 days) and chronic (10 months) treatment of human bronchial epithelial cells (HBEC3KT) cells with 10 µg/ml cigarette smoke condensate (CSC).. Homo sapiens

We define how chronic cigarette smoke-induced time-dependent epigenetic alterations can sensitize human bronchial epithelial cells (HBEC) for transformation by a single oncogene. The smoke-induced, chromatin changes include initial repressive polycomb marking of genes later manifesting abnormal DNA methylation by 10 months. At this time, cells manifest epithelial to mesenchymal changes, anchorage-independent growth and upregulated RAS/MAPK signaling with silencing of hyper-methylated genes normally inhibiting these pathways and which are associated with smoking related NSCLC. These cells, in the absence of any driver gene mutations, now transform by introducing a single KRAS mutation and form adeno-squamous lung carcinomas in mice. Thus, epigenetic abnormalities may prime for changing oncogene senescence to addiction for a single key oncogene involved in lung cancer initiation. Overall design: HBEC cells treated with 10 µg/ml CSC for 10 months. Control (DMSO treated) and CSC treated cells were harvested at 10 days (acute exposure) and 10 months (chronic exposure) and processed for ChIP to examine genome wide enrichment of H3K4me3, H3k27me3 and binding of DNMT1 and EZH2. ChIPed DNA was analyzed by ChIP-seq.