Examination of genome-wide methylation changes in lung cancer cell lines A549 (A) and HTB56 (H) [RRBS-Seq experiments]

Cancer cell phenotypes are partially determined by epigenetic specifications such as DNA methylation. Metastasis development is a late event in cancerogenesis and might be associated with epigenetic alterations. Here, we analyzed genome wide DNA methylation changes that were associated with pro-metastatic phenotypes in non-small cell lung cancer with Reduced Representation Bisulfite Sequencing. DNMT-inhibition by 5-Azacytidine at low concentrations reverted the pro-metastatic phenotype. 5-Azacytidine led to preferential loss of DNA methylation at sites that were DNA hypermethylated during the in vivo selection. Changes in DNA methylation persisted over time. Keywords: Methylation profiling by high throughput sequencing Overall design: We studied genome-wide methylation changes in lung cancer cell lines A549 (A) and HTB56 (H). We generated NSCLC lines with highly increased propensity to form tumor nodules in murine lungs after intravenous injections. In addition to the normal cell lines (0R) we analyzed the methylome of the the cell lines after three rounds of in vivo selection towards a highly metastatic phenotype (3R). Next we studied changes in the methylome of highly metastatic cell lines after DNA Methyltransferase inhibition by 5-Azacytidine treatment at low concentrations (250 nM & 1000 nM) for 6 days. During treatment cells were supplemented with fresh medium every 48 hours. After 6 days of 5-Azacytidine exposure, cells were washed three times with PBS to wash out the drug. The cells were released for additional 7 days in regular medium. We followed up the DNA methylation changes at day 13 of the experiment.