DNA and Histone Methylation in Brain Cancer

Abstract

Brain tumors are not rare solid cancer. Among them, gliomas are the most frequently occurring primary brain tumors in adults. Although they exist in different malignant stages, including histologically benign forms and highly aggressive states, most gliomas are clinically challenging for neuro-oncologists because of their infiltrative growth patterns and inherent relapse tendency with increased malignancy and dismal prognosis. Extensive genetic analyses of glioma have revealed a variety of deregulated genetic pathways involved in DNA repair, apoptosis, cell migration/adhesion, and cell cycle. Recently, it has become evident that epigenetic alterations may also be an important factor for glioma genesis. Epigenetic events can be defined as mitotically heritable changes in gene expression that are not due to changes in the primary DNA sequence. Epigenetic mechanisms, including those involving enzymatic modifications to DNA or histone proteins, thereby regulating gene expression, are increasingly recognized as a source of phenotypic variability in biology. Of epigenetic marks, DNA and histone methylation is a key mark that regulates gene expression and thus modulates a wide range of oncogenic processes. In this review, I discuss the neuro-oncological significance of DNA and histone methylation in patients with brain cancer while briefly overviewing the biological roles of histone modifications.