DNA methylation biomarkers for the occurrence of lung adenocarcinoma from TCGA data mining.

The development of lung cancer is a combination of multifactor, multistage, and multiple genetic alterations processes. DNA methylation is an important factor. Currently, the study on the genome-scale epigenetic modification for studying the pathogenesis of lung cancer is still lacking. Here, we aimed to identify the epigenetic modifications of lung cancer, thus to provide scientific basis for the personalized medicine, and research of classification screening for lung adenocarcinoma patients. The DNA methylation data, and the corresponding clinical information of lung adenocarcinoma samples were extracted from the Cancer Genome Atlas (TCGA) database. We explored the association of DNA methylation and gene transcription expression of lung adenocarcinoma by identifying the differentially expressed genes, DNA methylated locis, functional gene clusters, and the relevant genes associated with the survival. We identified 17 differentially expressed genes which had differentially methylated locis, 4 functional gene clusters regulated by methylation, and 522 genes, which were relevant to the survival time of patients. Our study suggested that methylation controlled the gene expression in a variety of ways, which had high/low expression and hyper-/hypo-methylation. Genes of different methylation status showed the different survival curve. The genes and methylated locis identified in this study could be potential biomarkers and therapeutic targets for lung adenocarcinoma.