The fundamental and basic unit of cell chromatin is nucleosome which contains the core histone octamer and the associated DNA chain

The fundamental and basic unit of cell chromatin is nucleosome which contains the core histone octamer and the associated DNA chain (1). Chromatin organization plays an important role for many cellular processes, such as recombination, replication transcription, repair, and chromosome segregation. Furthermore, post-translational histone modifications influence chromatin structure and gene transcription (2). Specific amino acids of histone proteins are targets for a number of post-translational histone modifications such as ubiquitination, acetylation, methylation, and phosphorylation (3). Therefore, a special region of histone is the target of several types of post-translational histone modifications. Meanwhile, post-translational histone modifications play basic epigenetic regulatory roles including transcription, elongation, and gene silencing (4). As mentioned, the balance between the activity of HATs and HDACs determine the level of histone acetylation which is responsible for setting patterns of acetylation across the cellular genome (5). The activity of these enzymes determine the fate of the transcriptional activation (3). HDACs transfer an acetyl group from acetyl-CoA molecules to the lysine “-amino groups on the N-terminal tails of histones and are the most important target of histone deacetylase inhibitors (HDACIs) (6). Histone deacetylation is one of the epigenetic events linked to the development of malignancies and pathogenesis. In vitro studies have been demonstrated that a number of HDACIs can induce cancer cells differentiation, cell apoptosis, and cell growth inhibition in a wide variety of transformed cells, including leukemia, melanoma, prostate, ovarian, breast, lung, and colon cancers (7).
HDACI compounds contain several chemical structural classes. HDACIs valproic acid (VPA) is a short chain fatty acid has a history of clinical administration as an