Analysis of DNA methylation of E‐cadherin and p16(ink4a) in oral lichen planus/oral lichenoid lesions

OBJECTIVES: Epigenetic phenomena are changes in gene expression not involving the DNA sequence. DNA methylation is a major occurrence underlying epigenetic changes in human cells. Although aberrant DNA methylation is well documented in malignant lesions, limited information has been shown on the involvement of DNA methylation in oral lichen planus and oral lichenoid lesions (OLP). The present study aimed to investigate DNA methylation of E‐cadherin and p16 in OLP, and compare the findings with those in non‐inflamed gingiva (Non), radicular cyst (RC), and oral squamous cell carcinoma (SCC). MATERIALS AND METHODS: Paraffin‐embedded surgical biopsy specimens were sliced, DNA was extracted, bisulfite treatment was applied, and methylation‐specific polymerase chain reaction was performed. Immunohistochemistry was performed to observe the relative expression patterns of these genes. RESULTS: E‐cadherin was hypermethylated in OLP (p < 0.01), SCC (p < 0.01), and RC (p < 0.05), when compared with Non; DNA hypermethylation was confirmed in OLP and SCC when compared to Non and RC. Hypermethylation of p16(ink4a) was observed only in SCC (p < 0.01). CONCLUSION: DNA methylation levels of E‐cadherin and p16(ink4a) were significantly higher in OLP than in normal tissues, and may be associated with the pathogenesis and progression of the disease.