Relationship of EGFR DNA methylation with the severity of non-small cell lung cancer

The aim of this study was to study the relationship of EGFR DNA methylation with the severity of non-small-cell lung cancer (NSCLC). We enrolled 54 patients with NSCLC between March 2013 and June 2014 from Department of Cardiothoracic Surgery in our hospital. The methylation levels in the promoter region of the EGFR gene in cancerous and pericarcinomatous tissue were tested by pyrosequencing. EGFR mRNA expression levels were detected by real-time reverse-transcription polymerase chain reaction. The SPSS software was used for data analysis. We found that EGFR gene methylation levels showed no significant differences among patients of different gender, age, or smoking status. EGFR DNA methylation levels significantly increased (P < 0.05) following NSCLC malignancy upgrading, and showed negative correlation with mRNA expression (P = 0.041). DNA methylation levels of cancerous tissues were significantly higher compared to the corresponding pericarcinomatous tissues (P < 0.05) at stages I, II, and IIIA. The methylation levels at loci 3, 6, 9 among the detected CpG islands were higher in the cancer tissues at each stage (P < 0.05). In summary, our results suggest that the DNA methylation levels of EGFR can be used as an important indicator for the stage of cancer tissue malignancy.