High Frequency of DNA Hypermethylation in Lichen Planus

Objectives: Epigenetics is described as changes in the pattern of gene expression not involving the DNA sequence. DNA methylation is a major mechanism of epigenetic alteration in human cells. Although aberrant DNA methylation is well documented in malignant lesions, little information about involvement of DNA methylation has been shown in oral lichen planus. The present study investigated DNA methylation of E-cadherin, beta-catenin, p16 and O(6)-Methylguanine-DNA methyltransferase (MGMT) in oral lichen planus.
Methods: The paraffin-embedded tissue samples obtained from oral lichen planus (OLP), radicular cyst (Rc), squamous cell carcinoma (SCC) and non-inflammation gingiva (Non-I) were used in this study. DNA was extracted and treated with sodium bisulfite using EpiTec Plus FFPE Bisulfite Kits (Qiagen). Quantitative-Methylation Specific PCR(SYBR® Green) was performed using specific primers for E-cadherin, beta-catenin, p16 and MGMT. Data was shown as the ratio of methylation to unmethylation, and was divided into four groups; A<1%, 1%≦B<10%, 10%≦C<50%, 50%≦D. Results were statistically analyzed by chi-squared test.
Results: The chi-square test showed that the frequency of B group of E-cadherin in OLP was 66.7%, which was significantly higher than that in Rc or Non-I. The frequency of C group of beta-catenin in OLP was 56.7%, which was significantly higher than that in Rc or Non-I. The frequency of C group of MGMT in OLP was 56.6%, which was significantly higher than that in Rc or Non-I. No significant differences were observed between OLP and Rc or No-I in the frequency of hypermethylation of p16.
Conclusions: The results indicate that DNA hypermethylation may be involved in pathological changes in OLP. The hypermethylation may be a therapeutic target for OLP.