Identification and Validation of DNA Methylation Markers to Predict Lymph Node Metastasis of Esophageal Squamous Cell Carcinomas

Background The presence of lymph node metastasis in esophageal squamous cell carcinoma (ESCC) patients is a critical factor for decision of treatment strategy. However, there have been no molecular markers to assess lymph node metastasis. In this study, we aimed to identify CpG islands (CGIs) whose DNA methylation statuses are associated with the presence of lymph node metastasis. Materials and Methods A total of 96 ESCCs were divided into a screening set ( n = 48) and a validation set ( n = 48). Genome-wide methylation analysis was performed by methylated DNA immunoprecipitation-CGI microarray analysis. Methylation levels were analyzed by quantitative methylation-specific PCR (qMSP). Results Genome-wide methylation analysis identified 25 CGIs differentially methylated between 8 ESCCs with lymph node metastasis and 4 without. In the screening set, 7 CGIs had significantly different methylation levels ( P