Assessment of DNA methylation for the detection of cervical neoplasia in liquid-based cytology specimens.

OBJECTIVE

DNA methylation is an early event in carcinogenesis. Testing for DNA methylation has potential in cancer screening. The aim of this study was to investigate the feasibility of methylated DNA detection as a screening tool for squamous cell carcinomas (SCC) and squamous intraepithelial lesions (SIL) in cervical scrapings.

METHODS

A multiplex, nested, methylation-specific polymerase chain reaction approach was used to examine promoter methylation of 12 genes (CDH1, DAPK, GSTP1, HIC-1, HIN-1, hMLH1, MGMT, p16, RAR-beta, RASSF1A, SHP-1, and Twist) in biopsy-proven SCC (n=69), high-grade SIL (HSIL, n=67), low-grade SIL (LSIL, n=32), and negative (n=41) liquid-based cytology samples.

RESULTS

The methylation frequency in normal, LSIL, HSIL, and SCC was significantly different (p<0.01) for eight genes (DAPK, HIC-1, HIN-1, MGMT, RAR-beta, RASSF1A, SHP-1, and Twist). There was a trend toward increasing methylation of HIN-1, MGMT, RAR-beta, RASSF1A, and SHP-1 with increasing severity of cervical squamous lesions. The number of methylated genes increased with the severity of cervical squamous lesions (p<0.001). In receiver-operating characteristic analysis, the three-gene combination (RAR-beta/Twist/MGMT) showed the best performance to distinguish HSIL/SCC from LCIS/negative samples. The estimated specificity of this three-gene panel for detecting HSIL/SCC was 82.2%, and its sensitivity was 78.7%.

CONCLUSION

Although aberrant DNA methylation has the potential to function as a molecular biomarker of HSIL and SCC in liquid-based cytology tests, additional genes that are selectively methylated in HSIL and SCC are needed to improve clinical performance.