LINE-1 hypomethylation is inversely correlated with UHRF1 overexpression in gastric cancer.

DNA methylation is an important epigenetic modification that alters gene expression; DNA hypomethylation contributes to tumorigenesis through multiple processes. In the present study, the methylation of long interspersed element-1 (LINE-1) in 95 gastric cancer (GC) tissues and matched adjacent normal tissues was investigated by pyrosequencing. LINE-1 methylation was compared with the expression of ubiquitin-like with PHD and ring-finger protein 1 (UHRF1), an essential regulator of DNA methylation, using reverse transcription-quantitative polymerase chain reaction. Significant hypomethylation of LINE-1 and overexpression of UHRF1 were observed in GC tissues compared with the matched controls (P<0.001 and P=0.001, respectively). LINE-1 hypomethylation was inversely correlated with UHRF1 overexpression in GC tissues (r=-0.026, P=0.028). In addition, LINE-1 hypomethylation in GC was significantly associated with Lauren's histological classification, tumor differentiation and background intestinal metaplasia (P=0.014, P=0.042 and P=0.034, respectively). These results suggest that LINE-1 hypomethylation may be a potential biomarker for GC and it is indirectly regulated by UHRF1 overexpression.