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At least 793 records · Page 44Linked to original sources
PubMed1997

Sodium butyrate inhibits the expression of the human lecithin: cholesterol acyltransferase gene in HepG2 cells by a post-transcriptional mechanism.

We have previously demonstrated that LCAT is downregulated by TGF-beta and that the regulation is post-transcriptional and involves an increased rate of RNA degradation. Sodium butyrate affects the expression of several liver-specific genes including some whose levels are altered during an acute-phase response. We have investigated the effect of sodium butyrate on LCAT activity and mRNA levels in HepG2 cells. Both the LCAT mRNA level and activity were reduced in a dose- and time-dependent manner. The reduction of LCAT mRNA levels was not, however, due to an increased degradation of processed mRNA. The transcriptional activity of the LCAT gene as seen in run-on experiments was not affected by sodium butyrate, whereas the total level of LCAT transcripts was reduced. Thus, LCAT activity and mRNA level in HepG2 cells are decreased by sodium butyrate treatment by a post-transcriptional mechanism, most likely involving increased degradation of pre-mRNA.

Butyrates↗
PubMed1993

Chronic pouchitis after ileal pouch-anal anastomosis: responses to butyrate and glutamine suppositories in a pilot study.

Nonspecific, idiopathic inflammation of ileal pouch mucosa ("pouchitis") after ileal pouch-anal anastomosis is a common complication of this surgical approach. The epithelium of the pouch is ileal, but variable degrees of colonic metaplasia are natural sequelae of construction of such a pouch. One hypothesis is that pouchitis is caused by a deficiency of epithelial nutrition. Thus, a lack of butyric acid (the principal metabolic fuel of colonocytes) or of glutamine (the main fuel of enterocytes) may develop. In this study, our aims were to determine the concentration of total short-chain fatty acids in random stool samples obtained from patients with an ileal pouch-anal anastomosis with and without pouchitis and to test the therapeutic effects of butyrate and glutamine suppositories on pouchitis. During the study, all conventional therapy for pouchitis was discontinued. For 21 days, 9 patients participated in a butyrate trial, and 10 patients were treated with glutamine. Total concentrations of fecal short-chain fatty acids were significantly less in patients with pouchitis than in those without pouchitis. During treatment, 6 of the 10 patients who received glutamine had no recurrence of symptoms, but only 3 of the 9 patients who received butyrate responded similarly. Hence, further studies of glutamine in the treatment of pouchitis seem warranted.

Adolescent↗
PubMed1997

Adrenergic differentiation potential in PC12 cells: influence of sodium butyrate and dexamethasone.

The ability of sodium butyrate and dexamethasone to promote adrenergic differentiation in PC12 cells was examined using the gene encoding the epinephrine biosynthetic enzyme, phenylethanolamine N-methyltransferase (PNMT), as a marker. Sodium butyrate and dexamethasone independently stimulated expression of PNMT mRNA in PC12 cells, and the combined action of these drugs led to synergistic activation of the PNMT gene. Despite the induction of the PNMT gene, epinephrine is not produced in these cells, in part due to the absence of a corresponding induction in PNMT enzymatic activity. Another contributing factor appears to be a reduction in the precursor catecholamines, norepinephrine and dopamine, in the presence of sodium butyrate. Thus, while sodium butyrate and dexamethasone can induce PNMT gene expression, treatment of PC12 cells with these drugs appears insufficient for full acquisition of the adrenergic phenotype.

Adrenal Glands↗
PubMed1983

Rearrangements of chromatin structure in newly repaired regions of deoxyribonucleic acid in human cells treated with sodium butyrate or hydroxyurea.

The rate and extent of redistribution of repair-incorporated nucleotides within chromatin during very early times (10-45 min) after ultraviolet irradiation were examined in normal human fibroblasts treated with 20 mM sodium butyrate, or 2-10 mM hydroxyurea, and compared to results for untreated cells. Under these conditions, DNA replicative synthesis is reduced to very low levels in each case. However, DNA repair synthesis is stimulated by sodium butyrate and partially inhibited by hydroxyurea. Furthermore, in the sodium butyrate treated cells, the core histones are maximally hyperacetylated. Using methods previously described by us, it was found that treatment with sodium butyrate had little or no effect on either the rate or the extent of redistribution of repair-incorporated nucleotides during this early time interval. On the other hand, there was a 1.7-2.5-fold decrease in the rate of redistribution of these nucleotides in cells treated with hydroxyurea; the extent of redistribution was unchanged in these cells. Since hydroxyurea has been shown to decrease the rate of completion of "repair patches" in mammalian cells, these results indicate that nucleosome rearrangement in newly repaired regions of DNA does not occur until after the final stages of the excision repair process are completed. Furthermore, hyperacetylation of the core histones in a large fraction of the total chromatin prior to DNA damage and repair synthesis does not appear to alter the rate or extent of nucleosome core formation in newly repaired regions of DNA.

Butyrates↗
PubMed1998

Sodium butyrate-induced liver-type alkaline phosphatase activity in a small intestinal epithelial cell line, IEC6.

Sodium butyrate is a well-recognized differentiating agent inducing alkaline phosphatase activity, one of the epithelial differentiation markers. When IEC6 cells, a nontransformed, small intestinal epithelial cell line, were cultured with butyrate, this substrate induced alkaline phosphate activity in a time- and dose-dependent fashion. However, the type of isoenzyme involved was a liver-type, not an intestinal-type. Electron microscopy revealed that the induced activity was strictly localized in the cytosol and not on the plasma membrane. However, disaccharidase activities, another kind of differentiation marker, were also enhanced by sodium butyrate. In addition, the positive cells demonstrating the presence of alkaline phosphatase activity were preferentially observed in tubular structures. These data show that butyrate-induced alkaline phosphatase activity is closely associated with differentiation-like phenomena in IEC6 cells, although the type of isoenzyme and cellular localization of the activity are different from those observed in mucosa.

Alkaline Phosphatase↗
PubMed1998

Transforming growth factor beta 1 and sodium butyrate differentially modulate urokinase plasminogen activator and plasminogen activator inhibitor-1 in human breast normal and cancer cells.

The effects of transforming growth factor beta 1 (TGF-beta1) and sodium butyrate on cell proliferation and the urokinase plasminogen activator (uPA) system were examined in normal human breast epithelial cells (HBECs) and in a breast cancer cell line, MDA-MB-231. In HBECs, TGF-beta1 inhibited cell proliferation and uPA activity, while it augmented plasminogen activator inhibitor-1 (PAI-1) antigen level. Sodium butyrate inhibited both cell proliferation and uPA activity but did not affect the level of PAI-1. In MDA-MB-231, TGF-beta1 had no effect on cell proliferation but increased uPA activity and PAI-1 antigen level; sodium butyrate inhibited both cell proliferation and uPA activity but had no effect on PAI-1 level. Moreover, in the presence of plasminogen, cell detachment could be modulated by the level of cell-associated uPA. Our results indicate (1) that the effects of TGF-beta1 on cell growth can be dissociated from its effects on the uPA/PAI system; (2) that, while TGF-beta1 is a potent inhibitor of cell proliferation and uPA activity in normal cells, it may promote invasion and metastasis of tumour cells by increasing uPA activity and PAI-1 levels; and (3) that sodium butyrate offers a potential approach to preventing tumour development by inhibiting both cell proliferation and invasion.

Breast↗
PubMed1985

Butyrate formation from glucose by the rumen protozoon Dasytricha ruminantium.

Production of butyrate by the holotrich protozoon Dasytricha ruminantium involves the enzymes of glycolysis, pyruvate:ferredoxin oxidoreductase, acetyl-CoA:acetyl-CoA C-acetyltransferase, 3-hydroxybutyryl-CoA dehydrogenase, 3-hydroxyacyl-CoA hydro-lyase, 3-hydroxyacyl-CoA reductase, phosphate butyryltransferase and butyrate kinase. Subcellular fractionation by differential and density-gradient centrifugation on sucrose gradients indicated that all those enzymes except pyruvate:ferredoxin oxidoreductase were non-sedimentable at 6 X 10(6) g-min. Butyrate kinase and phosphate butyryltransferase were associated with the large- and small-granule fractions. Thus, although metabolic reactions necessary for butyrate production proceed predominantly in the cytosol, hydrogenosomes play a key role in the conversion of pyruvate into acetyl-CoA.

Animals↗
PubMed1990

Induction of carcinoembryonic-antigen-gene expression in human colorectal carcinoma by sodium butyrate.

The effect of sodium butyrate on the expression of the carcinoembryonic-antigen (CEA) gene was studied in two poorly differentiated colorectal-carcinoma cell lines (Clone-A and MIP-101) and in one well-differentiated cell line (LS-174T); A.T.C.C. no. CCL 188). Northern-blot and dot-blot analyses indicated a steady increase in CEA mRNA from day 4 to a maximal level by day 14 after these cells were exposed to 2 mM-sodium butyrate. Studies using nuclear run-off assays followed by dot-blot hybridization to a partial CEA cDNA clone demonstrated that specific increases in gene transcription rates (3-fold in MIP-101, 4-fold in LS-174T and 6-fold in Clone-A) are not sufficient to account for the observed increases in CEA mRNA abundance. Further studies showed that CEA-specific transcripts have a half-life of about 60-80 min, and treatment with sodium butyrate increased the stability of CEA-specific transcripts to about 340 min in LS-174T cells and to about 500 min in Clone-A cells. We conclude that the induction of the CEA-gene expression by sodium butyrate in colorectal-cancer cells is mediated by both transcriptional and post-transcriptional mechanisms, with CEA mRNA stability as one of the major check-points.

Butyrates↗
PubMed1997

P52PAI-1 gene expression in butyrate-induced flat revertants of v-ras-transformed rat kidney cells: mechanism of induction and involvement in the morphological response.

Sodium n-butyrate-induced flat reversion in v-K-ras oncogene-transformed rat kidney (KNRK) cells is associated with transcriptional activation of the p52PAI-1 gene (which encodes the type-1 inhibitor of plasminogen activator). Butyrate-initiated expression of p52PAI-1 mRNA and protein correlated with induced cell spreading and preceded development of cell-to-substrate focal adhesions. Such undersurface matrix contact structures, which are absent from parental KNRK cells, require proximal PAI-1 deposition for their stabilization. Stimulated p52PAI-1 expression by flat revertants (approximating 25-fold that of control cells) and the accompanying cytoarchitectural reorganization appeared to be programmed responses to butyrate as both events required de novo RNA and protein synthesis, metabolic characteristics consistent with a secondary pathway of gene regulation. To assess the relevance of p52PAI-1 induction to the process of flat reversion more critically, a molecular genetic approach was designed to maintain high-level constitutive p52PAI-1 synthesis in the absence of butyrate. KNRK cells transfected with a Rc/CMVPAI plasmid construct, in which expression of a p52PAI-1 cDNA insert was driven by enhancer-promoter sequences from the immediate-early gene of human cytomegalovirus, formed colonies comprised of flat-revertant-like cells with a greater frequency than did cells transfected with the Rc/CMV vector alone (24.8% and 1.7% respectively). Comparative analysis of randomly selected Rc/ CMVPAI clones indicated that a 10-fold increase in immunoreactive p52PAI-1 protein, relative to Rc/CMV isolates, correlated with generation of the flat phenotype. These data suggest that induced p52PAI-1 expression probably functions in the development of morphological revertants in the KNRK cell system.

Animals↗
PubMed1996

Butyrate enhances major histocompatibility complex class I, HLA-DR and ICAM-1 antigen expression on differentiated human intestinal epithelial cells.

Besides its metabolic role, butyrate, a by-product of colonic fermentation, can modulate colonocyte proliferation and the expression of various molecules. In inflammatory bowel diseases, epithelial cells express HLA class II molecules and may behave as antigen-presenting cells. This study was performed to characterize the effect of butyrate on major histocompatibility complex expression by human colonocytes in comparison with interferon-gamma. Five cell lines displaying different differentiation features were analysed for antigen expression by flow cytofluorimetry. All lines expressed class I antigens, whereas only SW 1116 cells express HLA-DR. On these cells, butyrate and interferon-gamma strongly enhanced HLA-DR and ICAM-1 expression, whereas a mild increase in class I antigens was noted. Moreover, an increase in class I antigens was observed on two other differentiated cell lines, and it was synergistic with interferon-gamma. Butyrate, by its modulation of HLA-DR, ICAM-1 and HLA class I expression, may act on antigen presentation and, thus, influence some inflammatory processes.

Acetates↗
PubMed1997

Differentiation of BCS-TC2 human colon adenocarcinoma cells by sodium butyrate: increase in 5'-nucleotidase activity.

We have analysed the major effects of sodium butyrate on the morphology, protein content and induction of epithelial differentiation markers in human colon adenocarcinoma BCS-TC2 cells. Sodium butyrate alters the cell morphology, inducing a larger cellular size, flattening and vacuolization. The protein content per cell increases, whereas the proliferation rate is reduced. Moreover, cell death by apoptosis is also observed. Butyrate-treated cells show higher levels of alkaline phosphatase activity and carcinoembryonic antigen, suggesting that this agent induces the in vitro differentiation of BCS-TC2 cells. These effects are reversible and time and dose dependent. In addition, we have observed that the ectoenzyme 5'-nucleotidase activity also increases during this treatment, suggesting that it could be considered as a new differentiation marker for this type of carcinoma cells. These results contribute to the understanding of the action of sodium butyrate as a potential cancer chemotherapeutic agent.

5'-Nucleotidase↗
PubMed1997

Diet and carcinogen alter luminal butyrate concentration and intracellular pH in isolated rat colonocytes.

A 2 x 2 factorial experiment was conducted to examine the effects of two different dietary fibers and carcinogen treatment on colonic luminal short-chain fatty acid (SCFA) concentrations and intracellular pH (pHi) in rats. Twenty-four male Sprague-Dawley rats were divided into four groups, injected with a carcinogen [azoxymethane (AOM)] or normal saline (Sal), and fed one of two diets differing only in the type of dietary fiber [cellulose (Cell) or pectin (Pect)]. After 38 weeks of consuming these diets, the rats were euthanized, luminal contents were collected for analysis of SCFA concentrations, and colonocytes were isolated from the proximal and distal colon for subsequent determination of pHi. Changes in pHi after the addition of exogenous sodium butyrate to the culture medium were also tested. The highest concentrations of SCFAs were produced by the control rats (saline injected) consuming the pectin diet. Luminal butyrate concentrations were reduced in three of four colonic segments of carcinogen-injected groups [proximal and distal cellulose (Prox Cell and Dist Cell) and distal pectin (Dist Pect)] compared with saline controls. The pHi was consistently higher in colonocytes isolated from carcinogen-injected rats (Prox Cell/AOM = 6.95 vs. Prox Cell/Sal = 6.65, Prox Pect/AOM = 6.75 vs. Prox Pect/Sal = 6.65, Dist Cell/AOM = 6.94 vs. Dist Cell/AOM = 6.85, Dist Pect/AOM = 6.92 vs. Dist Pect/Sal = 6.79) than in cells from saline-injected rats. Furthermore, in the majority of rats, pHi was lower in the proximal than in the distal colon. Addition of butyrate to cultured colonocytes consistently lowered pHi, but the effect was more pronounced in the carcinogen-injected animals. These data identify changes that occur intraluminally and intracellularly in colons of rats injected with AOM and suggest that, during tumorigenesis, alterations in butyrate production and basic colonocyte physiology may play an important role in the process.

Animals↗
PubMed1994

Retrograde transport from the Golgi complex to the ER of both Shiga toxin and the nontoxic Shiga B-fragment is regulated by butyric acid and cAMP.

Endocytosed Shiga toxin is transported from the Golgi complex to the endoplasmic reticulum in butyric acid-treated A431 cells. We here examine the extent of this retrograde transport and its regulation. The short B fragment of Shiga toxin is sufficient for transport to the ER. The B fragment of cholera toxin, which also binds to glycolipids, is transported to all the Golgi cisterns, but cannot be localized in the ER even after butyric acid treatment. Under all conditions the toxic protein ricin was found predominantly in the trans-Golgi network. There is no transport of endocytosed fluid to the Golgi apparatus or to the ER even after butyric acid treatment and in the presence of Shiga toxin, indicating that transport to the ER, through the trans-Golgi network and the cisterns of the Golgi apparatus, involves several sorting stations. Since Shiga toxin receptors (Gb3) in butyric acid-treated A431 cells seem to have a ceramide moiety with longer fatty acids than in untreated cells, the possibility exists that fatty acid composition of the receptor is important for sorting to the ER. Both retrograde transport and intoxication with Shiga toxin can also be induced by cAMP, supporting the idea that retrograde transport from the Golgi to the ER is required for intoxication. The data suggest that transport to the ER in cells in situ may depend on fatty acid composition and is regulated by physiological signals.

Bacterial Toxins↗
PubMed1993

Effects of sodium butyrate on DNA content, glutathione S-transferase activities, cell morphology and growth characteristics of rat liver nonparenchymal epithelial cells in vitro.

The effects of sodium butyrate, which has been shown to act as a differentiation promoting agent in several different tumor cell lines, were studied in a rat liver nonparenchymal epithelial cell line. Exposure of these cells to 3.75 mM butyrate resulted in an inhibition of cell proliferation and, at the same time, an increase in cell diameter (2- to 6-fold) and size of the nuclei (approximately 2-fold) after 3 days in culture. Binucleated cells arose, comprising approximately 12% of the cells investigated, and the number of cells with an abnormal set of chromosomes was increased. Intercellular communication, measured by dye transfer of Lucifer Yellow, was unchanged. From the various xenobiotic metabolizing enzyme activities measured, only those of glutathione S-transferases were significantly altered (increases of 4- to 9-fold) by butyrate treatment. These increases were mainly due to the predominant rise in the pi class isoenzyme which is a well-known tumour marker in rat hepatocarcinogenesis. Thus, our results cannot be interpreted as being either due to promotion of differentiation or due to transformation. The state and type of cell under study has to be considered and investigations of further differentiation parameters are needed to obtain a deeper insight into the biological activity and the underlying mechanisms of cell state modifying agents like butyrate.

Animals↗
PubMed1988

Expression of carcinoembryonic antigen by adenoma and carcinoma derived epithelial cell lines: possible marker of tumour progression and modulation of expression by sodium butyrate.

We have used an indirect immunofluorescence assay to demonstrate the cell membrane expression of carcinoembryonic antigen (CEA) by a pre-malignant colorectal adenoma derived epithelial cell line (PC/AA) and three colorectal carcinoma cell lines (HT29, PC/JW and PC/JW/FI). The results obtained indicated that CEA may be used as a marker for tumour progression up to the point of malignant transformation, after which the selection for anaplastic variants during continuous in vitro culture may result in the subsequent reduction of cell membrane CEA expression. The percentage of PC/AA cells expressing cell membrane CEA increased from 23.1% of diploid early passage (passage 18) cells to 56.0% of aneuploid late passage (passage 58) cells. Although non-tumorigenic, the proportion of PC/AA cells expressing cell membrane CEA at late passage corresponded to that for the PC/JW carcinoma line (56.2%) and is further evidence for the progression of PC/AA in culture. A 3T3 feeder-independent variant of PC/JW (PC/JW/FI) demonstrated a similar percentage of CEA-positive cells as the parental line for the first 21 passages without feeder support, but by passage 27 without 3T3 feeders only 35.3% of cells stained positive. This could be restored to 62.0% by continuous treatment with sodium butyrate (2 mM). A differential growth response to sodium butyrate was noted for the pre-malignant adenoma cell line PC/AA and the carcinoma lines HT29 and PC/JW/FI. Concentrations of sodium butyrate (2 mM) that killed early passage PC/AA cells allowed the late passage PC/AA cells and the carcinoma lines to proliferate, raising the possibility of sodium butyrate acting as a tumour promotor in the human colorectum.

Adenoma↗
PubMed1984

RNA polymerase activity and template activity of chromatin after butyrate induced hyperacetylation of histones in Physarum.

We have studied the effect of sodium-n-butyrate on endogenous RNA polymerase in Physarum polycephalum. 1 mM butyrate strongly reduces RNA polymerase activity measured in isolated nuclei or chromatin; both RNA polymerase A as well as the alpha-amanitin sensitive RNA polymerase B are equally affected. Despite a concomitant hyperacetylation of histone H4 the template activity of chromatin, as analyzed by in vitro transcription of the chromatin with exogenous RNA polymerase from E. coli or RNA polymerase II from wheat germ, remains unaltered as compared to untreated control chromatin, indicating that there is no positive correlation between histone acetylation and template activity of chromatin for transcription in this organism. The results further indicate, that butyrate acts primarily as a quick but reversible inhibitor of protein synthesis in Physarum; the fast decrease of endogenous RNA polymerase activity after butyrate treatment is due to inhibition of enzyme synthesis rather than inactivation of other factors necessary for transcription.

Acetylation↗
PubMed1985

N-Butyrate incubation of immature chicken erythrocytes preferentially enhances the solubility of beta A chromatin.

The solubility of adult beta-globin chromatin (beta A chromatin) from immature chicken red blood cells can be controlled by the presence or absence of n-butyrate in a cell incubation medium. In the absence of n-butyrate, only a small percentage (approximately 4%) of the total beta A chromatin is in a soluble chromatin fraction following micrococcal nuclease digestion and centrifugation. This percentage increases to approximately 40-45% of the beta A chromatin if cells are incubated 1 hour in the presence of 10 mM sodium n-butyrate. The highest yield and enrichment of solubilized beta A chromatin is attained when 1-4% of the DNA is rendered acid soluble, and in buffers containing 1.5 - 5 mM MgCl2. The soluble beta A nucleohistone is nucleosome oligomer size (contains DNA 250-600 bases in length) and can be separated from soluble, transcriptionally inert mononucleosomes by agarose A-5m exclusion chromatography. The enhanced solubility appears to be specific for transcriptionally active chromatin. Whereas 40-45% of the beta A chromatin is recovered in the supernatant fraction from n-butyrate incubated immature erythrocytes, nucleohistone containing ovalbumin DNA sequences remains insoluble.

Acetylation↗
PubMed1997

Sodium butyrate decreases histamine-stimulated calcium mobilization in C6 glioma cells.

The aim of this study was to investigate the effect of sodium butyrate on calcium mobilization. Histamine was found to stimulate a dose-dependent increase in intracellular calcium concentrations ([Ca2+]i) through H1 receptors, but this effect was attenuated in C6 cells pretreated with 1-5 mM sodium butyrate. Evidence is provided that release of Ca2+ from intracellular stores is decreased in a dose-dependent manner. Experiments with BAPTA that show lower levels of [Ca2+]i in cells pretreated with higher concentrations of sodium butyrate suggest that sodium butyrate also decreases Ca2+ influx. These results suggest that changes in Ca2+ mobilization are at least partially responsible for sodium butylate-induced C6 cell differentiation.

Animals↗