== Global histone modifications and HDAC2 expression in human colon moderate to well differentiated cancers. stage of the disease were analyzed. HDAC2 nuclear expression was detected at high levels in 81.9%, 62.1%, and 53.1% of CRC, adenomas, and normal tissue, respectively (P= 0.002). The corresponding nuclear global expression levels in moderate to well differentiated tumors for H4K12 and H3K18 acetylation were increased while these levels were decreased in poorly differentiated tumors (P= 0.02). HDAC2 expression was correlated significantly with progression of adenoma to carcinoma (P= 0.002), with a discriminative power of 0.74, AG-1288 when comparing cancer and non-cancer cases. These results suggest HDAC2 expression is significantly associated with CRC progression. Keywords:Global histone acetylation, HDAC2, Colon cancer == Introduction == Colorectal carcinoma is the most common gastrointestinal malignancy. Overall mortality from colorectal cancer has declined since the 1980s. However, this decrease is primarily due to reduced mortality in Caucasians [1-3]. The death rate in Npy African Americans over this period is relatively unchanged. Both genetic and environmental risk factors play an important role in this disease. The over-whelming majority of cases of colorectal cancer are classified as sporadic. However, there is likely some inherited component to sporadic colorectal cancers, since there is an increased risk of cancer in those with a family history of colorectal cancer. In addition, a family history of colorectal adenomas is also a risk factor for developing colon cancer. Studies over the last two decades have identified factors that may protect against colorectal cancer including environmental and socioeconomical factors, exercise, as well as a nutritional diet including fruits, vegetables (low meat and animal fat diet) and fiber. While it is difficult to determine which of the above factors plays a major role in the observed differences between different ethnic groups, it is becoming clear that both genetic and epigenetic influences are important [4-6]. There is an increasing body of literature evaluating the impact of epigenetic changes on the development of several cancers, including colon cancer [7]. Studies have shown that many colon cancers have global DNA hypomethylation [7,8]. Relatively few studies, however, have specifically attempted to address the overall impact of chromatin modification, including histone modification, for colorectal cancer risk. Histone proteins, around which DNA is wrapped, can be chemically modified in several places by the addition of acetyl, methyl, or other groups. Histone acetylation and deacetylation are essential elements along with phosphorylation and methylation of an intricate histone code that regulates gene transcription [9,10]. The reversible process of histone acetylation is controlled by two classes of enzyme, histone acetyltransferases (HAT) and histone deacetylases (HDAC), which catalyze the addition to and removal of acetyl groups on lysine residues in proteins. Hyperacetylation of AG-1288 histones has been associated AG-1288 with transcriptional activation of genes as chromatin becomes accessible to a number of transcription factors and coactivator complexes [11,12]. Conversely, HDACs induce transcriptional repression by removing these acetyl groups, leading to chromatin condensation [13]. In addition to histones, both HATs and HDACs target non-histone protein substrates, such as transcription factors (e.g., p53) [14,15] and structural proteins (e.g., -tubulin) [16]. Deregulated HAT and HDAC activity plays a role in the development of a range of cancers, and inhibitors are being targeted in the clinic at different HDAC family members (i.e., class I, II, and III inhibitors) [17]. Histone modification can effect the activation and repression of oncogenes and tumor suppressor genes. Studies have shown that H3K18 and H4K12 acetylation can be used as predictive biomarkers for cancer recurrence in the prostate [18], and in non-small-cell lung cancer [19]. Alteration of histones (including hypo- and hyperacetylation) is related to promoter methylation of signature genes in cancer which can result in aberrant protein expression [8,20,21]. Histone.