Methylation analysis of HBEC cells exposed to cigarette smoke condensate (CSC) over a period of 15 months

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. Bisulphite converted DNA from control and CSC treated cells from two biological replicates (rep 1 and rep2) over a period of 15 months. Additionally methylation analysis of 15 month Control and CSC cells from both replicates expressing empty vector (EV) or mutant KRAS (KRASV12) and tumor xenografts obtained from CSC cells with KRASV12 from both replicates. DNA was hybridised to the Illumina Infinium 450k Human Methylation Beadchip