Genome‐wide DNA methylation profiling of gastric cardia cancer

Background and Aim Aberrant DNA methylation has been found in various cancer types including gastric cancer, yet the genome‐wide DNA methylation profile of gastric cardia cancer (GCC) remains unclear. Therefore, we aimed to profile the DNA methylation pattern of GCC and identify promising diagnostic epigenetic biomarkers. Methods We investigated the genome‐wide DNA methylation pattern in eight pairs of GCC and adjacent normal tissues using Illumina 850K microarrays. Subsequently, bisulfite‐pyrosequencing and quantitative real‐time PCR were performed on eight pairs of GCC‐adjacent normal tissues for validation. Finally, we performed immunohistochemistry to examine ADHFE1 expression on 126 pairs of GCC‐adjacent normal samples. Results DNA methylome analysis showed global hypomethylation and local hypermethylation of promoter cytosine‐phosphate‐guanine (CpG) islands (CGIs) in GCC tissues compared with gastric cardia normal mucosa (P