ABSTRACT
Cancer is a genetic and epigenetic disease [1-5]. Cancer cells are characterized by epigenetic dysregulation, including global genome hypomethylation, regional hypo-and hypermethylation, altered histone modifications, and disturbed genomic imprinting [6-11]. Histones have four basic subunits, and in the native state they exist as an octamer. DNA winds around this octamer. Acidic histones neutralize DNA charge and maintain chromatin stability. The octamer histone binding is independent of surrounding DNA sequence and the N-terminal region of histones is subject to phosphorylation, acetylation, and other modifications. Multiple histone modifications can take place within a short stretch of amino acids of histone tails [12-14]. These modifications regulate transcription, DNA replication, and DNA repair, and thus are part of the transformation process. Modification of histones may occur in large regions of chromatin, including coding and
nonpromoter sequences, termed global histone modifications. Global histone modifications have been suggested to play a role in cancer recurrence [13,15-18].
