Riteshkumar B Jadav, J G Ray, Antanu S Patsu, Naveen Kumar, Jayashree Paul, Shubhashish Pradhan
Department of Oral Pathology, Dr. R. Ahmed Dental College and Hospital, Kolkata, West Bengal, India
Background: Epigenetic changes include DNA methylation, histone modifications and aberrant mi-RNA expression. Inactivation of tumor suppressor genes by promoter hypermethylation and activation of oncogenes by hypomethylation at the gene promoters were commonly observed in various cancers including oral squamous cell carcinoma (OSCC). DNA repair gene O-6-methylguanine-DNA methyltransferase (MGMT) is crucial for genome stability. Inactivation of MGMT was observed in oral potentially malignant disorders (OPMDs) and OSCC patients. Aim: The aim of this study is to determine the CpG island methylation at the promoter of MGMT in OPMDs and OSCC patients and compare it with the adjacent normal tissues of the same patients. MGMT promoter methylation may be used as a biomarker for patient stratification and may help to develop appropriate therapy for OPMDs and OSCC patients. Materials and Methods: To achieve the aim, 10 OPMDs and 10 OSCC patients were recruited with written consent. Tissues from the lesion and adjacent normal sites were collected. Clinical observations were confirmed by histopathological evaluation. DNA was isolated from the tissues followed by bisulfite conversion. Methylation-specific polymerase chain reaction (PCR) was performed to determine the methylation status of the MGMT promoter. Results and Conclusion: Sixty percent of the OPMD patients showed hypermethylation, while one patient showed hypomethylation in lesions compared to the adjacent normal. However, in case of OSCC, only 30% showed hypermethylation in lesions compared to the adjacent normal. Remaining seven patients showed methylation both in the lesion and adjacent normal tissues. This data suggests that MGMT promoter methylation can be used as a biomarker in oral cancer progression.
Key words : Epigenetics, methylation, MGMT, oral cancer