DNA Methylation: An Epigenetic mechanism in oral squamous cell carcinoma

Abstract

Oral squamous cell carcinoma (OSCC) is one of the most common malignan-cies worldwide, despite the fact that during the last decade numerous ad-vancements have been made in its detection, prevention and treatment. Screening and early detection are assumed to decrease the morbidity and mortality associated with OSCC. Accurate diagnosis of precancerous reactive or inflammatory lesions via conventional visual and tactile examination is still problematic. Although many efforts have been made to define the molecular signatures that identify the clinical outcome of OSCC, still there is lack of a reliable prognostic molecular marker. The transformation from normal epi-thelium to pre-malignancy, and finally to oral carcinoma is a multistep pro-cess accompanied by accumulation of genetic and epigenetic alterations. Unlike genetic alterations, epigenetic changes are heritable and potentially reversible. In recent years, epigenetic inactivation of genes by promoter DNA hypermethylation has been recognized as an important and alternative mechanism of OSCC initiation and progression. DNA methylation of promot-er region occurs not only in OSCC but it has also been found in precancerous lesions. The aim of the present review is to assess the current state of knowledge on the epigenetic alterations observed in the pathogenesis of OSCC; focusing mainly on DNA methylation changes.