Promoter methylation of DAPK1, RAR-β and MGMT in exfoliated cervical cytology and its clinical application

Abstract

To assess the correlation of promoter methylation of DAPK1, RAR-β and MGMT with cervical lesions from cytology to histology, and to reveal the clinical value of DNA methylation in diagnosis of cervical intraepithelial neoplasia (CIN). A total of 103 random-selected cervical samples were collected from residual liquid-based cytology specimens after clinical use in cytopathological diagnosis in outpatient clinic of obstetrics and gynecology, Peking Union Medical Collage Hospital from March 2010 to October 2010. Informed consent was obtained from each woman before the initiation of the study. The methylation sensitive-high resolution melt (MS-HRM) assay was used to evaluate promoter methylation of three genes (DAPK1, RAR-β and MGMT) in 103 biopsy-confirmed liquid-based cervical cytology samples. Methylation levels and high-risk HPV DNA loading (HCII values) were analyzed in relation to both cytological and histological diagnosis. The methylation level of all three genes showed significant difference among the different cytological groups (P = 0.000, 0.011 and 0.002, respectively). The methylation level of DAPK1 and RAR-β showed significant difference among the different histological groups (P = 0.000 and 0.021), while there was no significant difference for MGMT. DAPK1 methylation levels was 1.47% in the CINII/high-grade precancerous lesions group, and 20.98% in the normal/CINI groups (P = 0.000), but there was no significant difference between CINII/high-grade precancerous lesions and normal/CINI groups for RAR-β and MGMT. The combination of DAPK1/HR-HPV loading showed a sensitivity of 0.825 and an area under the receiver operating characteristic curve (ROC) curve (AUC) of 0.695 as diagnostic methods for detecting CINII/high-grade precancerous lesions. DNA methylation such as DAPK1 and RAR-β, in combination with HR-HPV detection, may serve as biomarkers to detect CINII/high-grade precancerous lesions. Detection of methylated DNA from liquid-based cervical cytology specimens is technically feasible with the MS-HRM assay.