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Query: UMLS:C0699790 (colon cancer)
 28,837 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The role of histone hyperacetylation in regard to growth, differentiation, and apoptosis in colon cancer cells was assessed in an in vitro model system. HT-29 cells were grown in +/-10% fetal bovine serum with either 5 mM sodium butyrate or 0.3 microM trichostatin A [single dose (T) or 3 doses 8 h apart (TR)] for 24 h. Serum-starved HT-29 cells were further treated with epidermal growth factor or insulin-like growth factor I for an additional 24 h. Apoptosis was quantified with propidium iodide and characterized by electron microscopy. Northern blot analyses were performed with cDNA probes specific for intestinal alkaline phosphatase, Na-K-2Cl cotransporter, the cell cycle inhibitor p21, and the actin control. Flow cytometric analysis revealed a time-dependent growth suppression along with early induction of p21 mRNA in the butyrate, T, and TR groups. Histone hyperacetylation, assessed by acid-urea-triton gel electrophoresis, was transient in the T group but persisted for up to 24 h in the butyrate and TR groups. Induction of apoptosis, growth factor unresponsiveness, and differentiation occurred in the butyrate- and TR-treated cells but not those treated with a single dose of trichostatin A. Thus transient hyperacetylation of histones is sufficient to induce p21 expression and produce cellular growth arrest, but prolonged histone hyperacetylation is required for induction of the programs of differentiation, apoptosis, and growth factor unresponsiveness.
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PMID:Transient vs. prolonged histone hyperacetylation: effects on colon cancer cell growth, differentiation, and apoptosis. 1117 32

Histone deacetylases (HDACs) represent an expanding family of protein modifying-enzymes that play important roles in cell proliferation, chromosome remodeling, and gene transcription. We have previously shown that recombinant human HDAC8 can be expressed in bacteria and retain its catalytic activity. To further explore the catalytic activity of HDACs, we expressed two additional human class I HDACs, HDAC1 and HDAC3, in baculovirus. Recombinant HDAC1 and HDAC3 fusion proteins remained soluble and catalytically active and were purified to near homogeneity. Interestingly, trichostatin (TSA) was found to be a potent inhibitor for all three HDACs (IC50 value of approximately 0.1-0.3 microM), whereas another HDAC inhibitor MS-27-275 (N-(2-aminophenyl)-4-[N-(pyridin-3-methyloxycarbonyl)-aminomethyl]benzamide) preferentially inhibited HDAC1 (IC50 value of approximately 0.3 microM) versus HDAC3 (IC50 value of approximately 8 microM) and had no inhibitory activity toward HDAC8 (IC50 value >100 microM). MS-27-275 as well as TSA increased histone H4 acetylation, induced apoptosis in the human colon cancer cell line SW620, and activated the simian virus 40 early promoter. HDAC1 protein was more abundantly expressed in SW620 cells compared with that of HDAC3 and HDAC8. Using purified recombinant HDAC proteins, we identified several novel HDAC inhibitors that preferentially inhibit HDAC1 or HDAC8. These inhibitors displayed distinct properties in inducing histone acetylation and reporter gene expression. These results suggest selective HDAC inhibitors could be identified using recombinantly expressed HDACs and that HDAC1 may be a promising therapeutic target for designing HDAC inhibitors for proliferative diseases such as cancer.
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PMID:Identification of novel isoform-selective inhibitors within class I histone deacetylases. 1297 86

Epigenetic silencing is now recognized as a 'third pathway' in Knudson's model of tumor-suppressor gene inactivation in cancer and can affect gene function without genetic changes. DNA methylation within gene promoters and alterations in histone modifications appear to be primary mediators of epigenetic inheritance in cancer cells. For selected genes, epigenetic changes are tightly related to neoplastic transformation in colorectal cancers (CRCs). In the colon, aberrant DNA methylation arises very early, initially in normal appearing mucosa, and may be part of the age-related field defect observed in sporadic CRCs. Aberrant methylation also contributes to later stages of colon cancer formation and progression through a hypermethylator phenotype termed CpG Island Methylator Phenotype (CIMP), which appears to be a defining event in about half of all sporadic tumors. CIMP+ CRCs are distinctly characterized by pathology, clinical and molecular genetic features. Histone modifications, recently recognized as a 'histone code' that affects chromatin structure and gene expression also play an important role in the establishment of gene silencing during tumorigenesis. DNA methylation and histone H3 lysine 9 hypoacetylation and methylation appear to form a mutually reinforcing silencing loop that contributes to tumor-suppressor gene inactivation in CRCs. Understanding epigenetic alterations as a driving force in neoplasia opens new fields of research in epidemiology, risk assessment, and treatment in CRCs.
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PMID:Epigenetic changes in colorectal cancer. 1500 Jan 47

Intake of fibre has beneficial properties on gut health. Butyrate, a product of bacterial gut fermentation, is thought to contribute to positive effects by retarding growth and enhancing apoptosis of tumour cells. One mechanism is seen in its capacity to modulate histone acetylation and thereby transcriptional activity of genes. Next to butyrate, propionate and acetate are also major products of gut fermentation and together they may exert different potencies of cellular effects than butyrate alone. Since virtually nothing is known on combination effects by SCFA mixtures, here we had the aim to assess how physiological relevant concentrations and mixtures of SCFA modulate histone acetylation in human colon cells. HT29 colon cancer cells were incubated with mixtures of butyrate, acetate and propionate and with the individual compounds as controls. Histone acetylation was determined with acid-urea gel electrophoresis and immunoblotting. Acetylated histones slowly increased over 24 h and persisted up to 72 h in butyrate-treated HT29 cells. Butyrate (5-40 mM) and propionate (20-40 mM) enhanced histone acetylation significantly after 24 h incubation, whereas acetate (2.5-80 mM) was ineffective. Mixtures of these SCFA also modulated histone acetylation, mainly due to additive effects of butyrate and propionate, but not due to acetate. In conclusion, physiological concentrations of propionate together with butyrate could have more profound biological activities than generally assumed. Together, these SCFA could possibly mediate important processes related to an altered transcriptional gene activation and thus contribute to biological effects possibly related to cancer progression or prevention.
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PMID:Mixtures of SCFA, composed according to physiologically available concentrations in the gut lumen, modulate histone acetylation in human HT29 colon cancer cells. 1709 67

Epigenetic chromatin modification is a major regulator of eukaryotic gene expression, and aberrant epigenetic silencing of gene expression contributes to tumorigenesis. Histone modifications include acetylation, phosphorylation, and methylation, resulting in a combination of histone marks known collectively as the histone code. The chromatin marks at a given promoter determine, in part, whether specific promoters are in an open/active conformation or closed/repressed conformation. Dimethyl-lysine 4 histone H3 (H3K4me2) is a transcription-activating chromatin mark at gene promoters, and demethylation of this mark by the lysine-specific demethylase 1 (LSD1), a homologue of polyamine oxidases, may broadly repress gene expression. We now report that novel biguanide and bisguanidine polyamine analogues are potent inhibitors of LSD1. These analogues inhibit LSD1 in human colon carcinoma cells and affect a reexpression of multiple, aberrantly silenced genes important in the development of colon cancer, including members of the secreted frizzle-related proteins (SFRPs) and the GATA family of transcription factors. Furthermore, we demonstrate by chromatin immunoprecipitation analysis that the reexpression is concurrent with increased H3K4me2 and acetyl-H3K9 marks, decreased H3K9me1 and H3K9me2 repressive marks. We thus define important new agents for reversing aberrant repression of gene transcription.
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PMID:Inhibition of lysine-specific demethylase 1 by polyamine analogues results in reexpression of aberrantly silenced genes. 1746 86

Previously we found that a fruit-derived polyphenol fraction caused an inhibition of proliferation and an induction of differentiation markers in Caco-2 human colon cancer cells. In the present work, we sought to determine if individual polyphenols would exert similar actions. Proliferation was inhibited by several polyphenolic molecules including gallic acid, ellagic acid, quercetin and resveratrol. In Caco-2 cells, growth inhibition was accompanied by increased specific activities of two differentiation markers, alkaline phosphatase and dipeptidyl peptidase, but not of aminopeptidase. Increased enzyme activities were not seen in HT29 and SW1116 colon cancer cells. In Caco-2 cells there were additive effects of butyrate or valproate and polyphenolic molecules. Histone acetylation was not greatly affected by the polyphenols. Cycloheximide inhibited protein synthesis in the 3 cell types examined but paradoxically, in Caco-2 cells it caused increased specific activities of alkaline phosphatase and dipeptidyl peptidase. Several plant polyphenols can inhibit the growth of colon cancer cells but increased specific activity of some differentiation markers seen in Caco-2 cells did not appear to be a general phenomenon in colon cancer cells.
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PMID:Inhibition of growth and induction of differentiation markers by polyphenolic molecules and histone deacetylase inhibitors in colon cancer cells. 2033 34

Histone deacetylases (HDACs) are validated targets for anticancer therapy as attested by the approval of suberoylanilide hydroxamic acid (SAHA) and romidepsin (FK228) for treating cutaneous T cell lymphoma. We recently described the bioassay-guided isolation, structure determination, synthesis, and target identification of largazole, a marine-derived antiproliferative natural product that is a prodrug that releases a potent HDAC inhibitor, largazole thiol. Here, we characterize the anticancer activity of largazole by using in vitro and in vivo cancer models. Screening against the National Cancer Institute's 60 cell lines revealed that largazole is particularly active against several colon cancer cell types. Consequently, we tested largazole, along with several synthetic analogs, for HDAC inhibition in human HCT116 colon cancer cells. Enzyme inhibition strongly correlated with the growth inhibitory effects, and differential activity of largazole analogs was rationalized by molecular docking to an HDAC1 homology model. Comparative genomewide transcript profiling revealed a close overlap of genes that are regulated by largazole, FK228, and SAHA. Several of these genes can be related to largazole's ability to induce cell cycle arrest and apoptosis. Stability studies suggested reasonable bioavailability of the active species, largazole thiol. We established that largazole inhibits HDACs in tumor tissue in vivo by using a human HCT116 xenograft mouse model. Largazole strongly stimulated histone hyperacetylation in the tumor, showed efficacy in inhibiting tumor growth, and induced apoptosis in the tumor. This effect probably is mediated by the modulation of levels of cell cycle regulators, antagonism of the AKT pathway through insulin receptor substrate 1 down-regulation, and reduction of epidermal growth factor receptor levels.
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PMID:Anticolon cancer activity of largazole, a marine-derived tunable histone deacetylase inhibitor. 2073 54

Histone variant macroH2A1 has two splice isoforms, macroH2A1.1 and macroH2A1.2, with tissue- and cell-specific expression patterns. Although macroH2A1.1 is mainly found in differentiated, nonproliferative tissues, macroH2A1.2 is more generally expressed, including in tissues with ongoing cell proliferation. Consistently, studies in breast and lung cancer have demonstrated a strong correlation between macroH2A1.1 levels and proliferation, which is not the case for macroH2A1.2. This is the first study to assess the differential regulation and predictive potential of macroH2A1 isoforms in colon cancer. We found that macroH2A1.1 mRNA was down-regulated in primary colorectal cancer samples compared to matched normal colon tissue, whereas macroH2A1.2 was up-regulated. At the protein level, down-regulation of macroH2A1.1 correlated significantly with patient outcome (P = 0.0012), and loss of macroH2A1.1 was associated with a worse outcome. Over the course of Caco-2 cell differentiation, macroH2A1.1 was up-regulated at both the RNA and protein levels, whereas macroH2A1.2 was slightly down-regulated at the RNA level and stable at the protein level. These changes were accompanied by an antiproliferative phenotype exhibiting features of cellular senescence. Loss of macroH2A1.1 in vitro was characterized by a phenotype associated with cell growth and metastasis. These data demonstrate that macroH2A1 isoforms are differentially regulated in colon cancer, reflecting the degree of cellular differentiation. Notably, macroH2A1.1 expression predicts survival in colon cancer, thus identifying macroH2A1.1 as a novel colon cancer biomarker.
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PMID:Differential regulation and predictive potential of MacroH2A1 isoforms in colon cancer. 2254 94

Histone deacetylases (HDACs) and acetyltransferases have important roles in the regulation of protein acetylation, chromatin dynamics and the DNA damage response. Here, we show in human colon cancer cells that dietary isothiocyanates (ITCs) inhibit HDAC activity and increase HDAC protein turnover with the potency proportional to alkyl chain length, i.e., AITC < sulforaphane (SFN) < 6-SFN < 9-SFN. Molecular docking studies provided insights into the interactions of ITC metabolites with HDAC3, implicating the allosteric site between HDAC3 and its co-repressor. ITCs induced DNA double-strand breaks and enhanced the phosphorylation of histone H2AX, ataxia telangiectasia and Rad3-related protein (ATR) and checkpoint kinase-2 (CHK2). Depending on the ITC and treatment conditions, phenotypic outcomes included cell growth arrest, autophagy and apoptosis. Coincident with the loss of HDAC3 and HDAC6, as well as SIRT6, ITCs enhanced the acetylation and subsequent degradation of critical repair proteins, such as CtIP, and this was recapitulated in HDAC knockdown experiments. Importantly, colon cancer cells were far more susceptible than non-cancer cells to ITC-induced DNA damage, which persisted in the former case but was scarcely detectable in non-cancer colonic epithelial cells under the same conditions. Future studies will address the mechanistic basis for dietary ITCs preferentially exploiting HDAC turnover mechanisms and faulty DNA repair pathways in colon cancer cells vs. normal cells.
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PMID:HDAC turnover, CtIP acetylation and dysregulated DNA damage signaling in colon cancer cells treated with sulforaphane and related dietary isothiocyanates. 2377 Jun 84

Extensive evidence suggests that dysregulation of histone lysine acetylation is intimately linked with the development of cancer in epigenetic level. Histone acetylation on lysine is regulated mainly by the "pencil"--Histone acetyltransferases (HATs) and the "eraser"--Histone deacetylases HDACs. Dramatic elevation of global histone deacetylation is considered as a biomarker for cancer. Therefore, current antitumor drug design often targets HDACs, inhibiting overexpressed HDAC in tumor cells with natural or synthesized small molecules like largazole. Recently, a novel largazole derivative (largazole-7) was designed and prepared by replacement of Val 1 with tyrosine, and this modification increases selectivity toward human cancer cells over normal cells more than 100-fold. However, it is unclear about the dynamic level of histone acetylation under the treatment of this drug. It is also unclear whether the other modifications are also affected by largazole-7 treatment. Therefore, a global mapping of modifications on the histone proteins of cancer cell line treated by this drug may be of great benefit to elucidating its molecular mechanisms and exploring its potent as an antitumor drug. To realize the goal, we combined stable isotope labeling by amino acids in cell culture (SILAC) and high resolution MS for comprehensive identification and quantitative analysis of histone lysine acetylation and other modifications of Human Colon Cancer Cells (HCT-116) with and without treatment of largazole-7. In this analysis, we identified 68 histone PTMs in 38 sites on core histones, including lysine acetylation, methylation and butyrylation, a novel lysine modification. Further quantitative analysis not only discovered the global increased acetylated lysines, but also observed the changes of abundance of lysine methylation and butyrylation under stimulation of the drug. To our knowledge, it is the first report that regulation of largazole-7 against lysine butyrylation. Our study expands the catalog of histone marks in cancer, and provides an approach for understanding the known and new epigenetic marks under treatment of drugs.
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PMID:Comprehensive analysis for histone acetylation of human colon cancer cells treated with a novel HDAC inhibitor. 2388 55


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