Down-regulation of protein kinase CKII activity by sodium butyrate

An organic extract from ascidian Ciona robusta induces cytotoxic autophagy in human malignant cell lines

The last decades have seen an increase in the isolation and characterization of anticancer compounds derived from marine organisms, especially invertebrates, and their use in clinical trials. In this regard, ascidians, which are included in the subphylum Tunicata, represent successful examples with two drugs, Aplidine© and Yondelis© that reached the market as orphan drugs against several malignancies. Here, we report that an organic extract prepared from homogenized tissues of the Mediterranean ascidian Ciona robusta inhibited cell proliferation in HT-29, HepG2, and U2OS human cells with the former being the most sensitive to the extract (EC50 = 250 μg/mL). We demonstrated that the ascidian organic extract was not cytotoxic on HT-29 cells that were induced to differentiate with sodium butyrate, suggesting a preference for the mixture for the malignant phenotype. Finally, we report that cell death induced by the organic extract was mediated by the activation of a process of cytotoxic autophagy as a result of the increased expression of the LC3-II marker and number of autophagic vacuoles, which almost doubled in the treated HT-29 cells. In summary, although the detailed chemical composition of the Ciona robusta extract is still undetermined, our data suggest the presence of bioactive compounds possessing anticancer activity.

Antiproliferative and antioxidant effect of polar hemp extracts (Cannabis sativa L., Fedora cv.) in human colorectal cell lines

Total phenolic content and antioxidant activity of polar extracts of edible resources from Fedora hemp cultivar (Cannabis sativa L.), namely seed, flour and oil, were evaluated. The main components in the polar extracts were identified using HPLC-DAD and HPLC-ESI-MS/MS. As expected, the molecular profile of components from seeds and flour was strictly similar, dominated by N-trans-caffeoyltyramine. The profile of oil polar extracts contained hydroxycinnamic acid derivatives and cannabinoids at lower extent. While the extracts from hemp seed and flour did not interfere with growth of Caco-2 and HT-29 cell, the one from oil (150 µg/mL) significantly reduced cell viability after 24 h of treatment. This effect was associated with the activation of apoptotic cell death and was independent from the antioxidant capacity of the oil polar extract. Notably, HT-29 cells differentiated with sodium butyrate were not sensitive to the cytotoxic effect of the oil extract.

Increasing histone acetylation of cloned embryos, but not donor cells, by sodium butyrate improves their in vitro development in pigs

Previous studies have demonstrated that increased histone acetylation in donor cells or cloned embryos, by applying a histone deacetylase inhibitor (HDACi) such as trichostatin A (TSA), significantly enhances their developmental competence. However, its effect may vary with the type of HDACi and the target species, with some research showing nonsignificant or detrimental effects of TSA on in vitro and in vivo development of embryos. In this study, we show that sodium salt of butyric acid, a short-chain fatty acid produced naturally in the body by bacterial degradation of dietary fibers in the colon and rectum, increases histone acetylation in pig fibroblast and embryos at a concentration of 1.0 and 5.0 mM, respectively. However, treatment of donor cells with NaBu did not affect the rate of blastocyst formation or embryo quality in terms of histone acetylation and total nuclei per blastocyst (p > 0.05). On the contrary, treatment of cloned pig embryos with NaBu for 4 h significantly enhanced (p < 0.01) the rate of blastocyst formation (18.3 +/- 2.1 vs. 11.2 +/- 3.0%), although the total nuclei number per blastocyst did not differ. More importantly, blastocysts generated from NaBu-treated cloned embryos had increased levels of histone acetylation that was comparable to those of in vitro fertilized (IVF) embryos (36.7 +/- 3.6 vs. 45.9 +/- 2.5). In conclusion, our data suggest that histone hyperacetylation by NaBu treatment of cloned embryos, but not donor cell, enhances their in vitro development up to blastocyst stage.

Isoform-specific up-regulation of plasma membrane Ca2+ATPase expression during colon and gastric cancer cell differentiation

In this work we demonstrate a differentiation-induced up-regulation of the expression of plasma membrane Ca2+ATPase (PMCA) isoforms being present in various gastric/colon cancer cell types. We found PMCA1b as the major isoform in non-differentiated cancer cell lines, whereas the expression level of PMCA4b was significantly lower. Cell differentiation initiated with short chain fatty acids (SCFAs) and trichostatin A, or spontaneous differentiation of post-confluent cell cultures resulted in a marked induction of PMCA4b expression, while only moderately increased PMCA1b levels. Up-regulation of PMCA4b expression was demonstrated both at the protein and mRNA levels, and closely correlated with the induction of established differentiation markers. In contrast, the expression level of the Na+/K+-ATPase or that of the sarco/endoplasmic reticulum Ca2+ATPase 2 protein did not change significantly under these conditions. In membrane vesicles obtained from SCFA-treated gastric/colon cancer cells a marked increase in the PMCA-dependent Ca2+ transport activity was observed, indicating a general increase of PMCA function during the differentiation of these cancer cells. Because various PMCA isoforms display distinct functional characteristics, we suggest that up-regulated PMCA expression, together with a major switch in PMCA isoform pattern may significantly contribute to the differentiation of gastric/colon cancer cells. The analysis of PMCA expression may provide a new diagnostic tool for monitoring the tumor phenotype.

Effects of histone deacetylase inhibitors on p55CDC/Cdc20 expression in HT29 cell line

In a previous work, taking advantage of the gene-array screening technology, we analysed the effects of histone deacetylase (HDAC) inhibitor sodium butyrate (NaBt), on gene transcription in HT29 human adenocarcinoma cell line. In this study, we focused our attention on p55CDC/Cdc20 gene, whose expression was dramatically reduced by NaBt treatment. Mammalian p55CDC/Cdc20 interacts with the anaphase promoting complex/cyclosome (APC/C), and is involved in regulating anaphase onset and late mitotic events. Using NaBt and trichostatin A (TSA), a member of the HDAC inhibitor family, we showed that both HDAC inhibitors totally downregulated p55CDC/Cdc20 transcription and expression. Cell cycle analysis demonstrated that NaBt arrested HT29 cells in G0/G1 phase, while TSA caused a double block in G0/G1 and G2/M phases. Moreover, p55CDC/Cdc20 showed maximal expression in S and G2/M phases of HT29 cell division cycle. Based on this evidence, and by means of specific cell cycle modulators, such as nocodazole and hydroxyurea, we demonstrated that both TSA and NaBt were responsible for loss of p55CDC/Cdc20 expression, but with different mechanisms of action. Taken together, these results suggest that targeting molecules involved in spindle mitotic checkpoint, such as p55CDC/Cdc20, might account for the high cytotoxicity of HDAC inhibitors versus malignant cells.

Intraruminal infusion of n-butyric acid induces an increase of ruminal papillae size independent of IGF-1 system in castrated bulls

The objective of this study was to explore morphological alterations of rumen papillae induced by n-butyric acid in relation to the insulin-like growth factor (IGF) system in adult castrated bulls. Three animals fitted with rumen cannula were fed twice daily at a low and high nutritional level (LL and HL), i.e., at 1.1 x maintenance (M) and 1.6 x M, respectively. Diets contained artificial dried grass and concentrate (74:26 and 52:48). Bulls received no (B0) or daily intraruminal infusions of 500 g n-butyric acid (B500) over 14 d. The infusion started 1 h after the morning feeding (9:00) and lasted for 3.5 h. Thus, four treatments (BOLL, B500LL, BOHL, and B500HL) were compared. Blood and rumen mucosa samples from the atrium ruminis were taken at the last day of each period. Length, width and surface of rumen papillae were greater (p < 0.001) in BOHL than in BOLL. Treatment with n-butyric acid resulted in an increase of the papillae surface of 20-40% (p = 0.047) for both nutritional levels as compared to periods without n-butyric acid treatments. The higher nutritional level and intraruminal n-butyric acid infusion induced epithelial cell death. The percentage of proliferative cells was doubled by n-butyric acid treatment. The mRNA of IGF-1 and IGF type 1 receptor (IGF-1R), as well as IGF-1R binding capacity were unaffected by butyric acid treatments. The abundance of IGF-1 mRNA tended to be lower (p = 0.1) and IGF-1R abundance was lower (p = 0.03) in response to the HL. The plasma IGF-1 concentration was lower with butyric acid treatment (p < 0.01), but was unaffected by the nutritional level. In conclusion, under described experimental preconditions of daily short-time intraruminal n-butyric acid infusion alterations of rumen papillae morphology is not mediated by ruminal IGF type 1 receptor and by local IGF-1 expression in papillae in castrated bulls.

Biochemical and functional characterization of protein kinase CK2 in ascidian Ciona intestinalis oocytes at fertilization. Cloning and sequence analysis of cDNA for alpha and beta subunits

The ubiquitous and pleiotropic dual specificity protein kinase CK2 has been studied and characterized in many organisms, from yeast to mammals. Generally, the enzyme is composed of two catalytic (alpha and/or alpha') and two regulatory (beta) subunits, forming a differently assembled tetramer. Although prone to controversial interpretation, the function of CK2 has been associated with fundamental biological processes such as signal transduction, cell cycle progression, cell growth, apoptosis, and transcription. Less known is the role of CK2 during meiosis and the early phase of embryogenesis. In this work, we studied CK2 activity during oocyte activation, a process occurring at the end of oocyte maturation and triggered by fertilization. In ascidian Ciona intestinalis, an organism whose complete genome has been published recently, CK2 was constitutively active in unfertilized and fertilized oocytes. The enzymatic activity oscillated through meiosis showing three major peaks: soon after fertilization (metaphase I exit), before metaphase II, and at the exit from metaphase II. Biochemical analysis of CK2 subunit composition in activated oocytes indicated that CK2-alpha was catalytically active as a monomer, independently from its regulatory subunit beta; however, CK2-beta was only detectable in unfertilized oocytes where it was associated with a bona fide identified ascidian mitogen-activated protein kinase. After fertilization, CK2-beta was undetectable, suggesting its rapid degradation. Protein sequence analysis of CK2-alpha and -beta cDNA indicated a high identity compared with vertebrate homologs. In addition, the absence of putative phosphorylation sites for Cdc2 kinase on both alpha and beta subunits suggested an important role for CK2 in regulating meiotic cell cycle in C. intestinalis oocytes.

Transcriptional response of a human colon adenocarcinoma cell line to sodium butyrate

Taking advantage of the DNA array screening technology, we analysed the effect of sodium butyrate on mRNA transcription in human HT29 colon adenocarcinoma cells. Out of 588 mRNA species analysed, only 119 resulted expressed. Among these, 60 exhibited a variable degree of modulation after butyrate treatment. Genes linked to the cell growth, apoptosis and oxidative metabolism appeared the most significantly affected. Furthermore, many of the differentially expressed genes are transcription factors and this may account for the variability of the biological effects of butyrate. The pattern of butyrate-affected genes may represent a reference in further analyses of gene expression of intestinal cells and tissues.

Release characteristics of a short-chain fatty acid, n-butyric acid, from its beta-cyclodextrin ester conjugate in rat biological media

6(A)-O-(n-Butanoyl)-beta-cyclodextrin was prepared and its hydrolysis behavior in aqueous solutions and in rat intestinal fluids was investigated. Furthermore, the enzymatic hydrolyses of the n-butyric acid-beta-cyclodextrin conjugate using alpha-amylase and esterase were studied to gain insight into the release behavior of n-butyric acid from the conjugate. The hydrolysis of the conjugate proceeded according to a first-order kinetics in aqueous solution, and gave a V-shaped pH profile, indicating a specific acid-base-catalyzed hydrolysis at acidic and neutral-alkaline regions, respectively. The half-lives (t(1/2)) of the conjugate at pH 4.4, 6.8, and 7.4 at 37 degrees C were approximately 580, 43, and 6 days, respectively, indicating that the conjugate is stable in aqueous solution. No appreciable release of n-butyric acid from the conjugate was observed in the stomach and small intestinal contents of rats, or in the small and large intestinal homogenates of rats. On the other hand, a fast disappearance of the conjugate and an appearance of n-butyric acid were observed in the cecal and colonic contents of rats. The t(1/2) values of the disappearance were approximately 4, 1, and 6 h in 10 and 15% cecal contents and 10% colonic contents, respectively, and the appearance of n-butyric acid after 6 h was approximately 10% in the 15% cecal contents. Aspergillus oryzae alpha-amylase hydrolyzed the conjugate to small saccharide conjugates, such as the triose and maltose conjugates, but there was no appreciable release of n-butyric acid. The conjugate was less susceptible to carboxylic esterase (from porcine live), thus releasing no appreciable amounts of n-butyric acid. On the other hand, a fast release of n-butyric acid was observed when the esterase was employed after amylase hydrolysis, suggesting that two types of enzymes, sugar-degrading and ester-hydrolyzing enzymes, are necessary for the release of n-butyric acid from the conjugate in large intestinal contents.

Butyrate increases apical membrane CFTR but reduces chloride secretion in MDCK cells

Sodium butyrate and its derivatives are useful therapeutic agents for the treatment of genetic diseases including urea cycle disorders, sickle cell disease, thalassemias, and possibly cystic fibrosis (CF). Butyrate partially restores cAMP-activated Cl(-) secretion in CF epithelial cells by stimulating DeltaF508 cystic fibrosis transmembrane conductance regulator (DeltaF508-CFTR) gene expression and increasing the amount of DeltaF508-CFTR in the plasma membrane. Because the effect of butyrate on Cl(-) secretion by renal epithelial cells has not been reported, we examined the effects of chronic butyrate treatment (15-18 h) on the function, expression, and localization of CFTR fused to the green fluorescent protein (GFP-CFTR) in stably transfected MDCK cells. We report that sodium butyrate reduced Cl(-) secretion across MDCK cells, yet increased apical membrane GFP-CFTR expression 25-fold and increased apical membrane Cl(-) currents 30-fold. Although butyrate also increased Na-K-ATPase protein expression twofold, the drug reduced the activity of the Na-K-ATPase by 55%. Our findings suggest that butyrate inhibits cAMP-stimulated Cl(-) secretion across MDCK cells in part by reducing the activity of the Na-K-ATPase.

Butyrate augments interferon-alpha-induced S phase accumulation and persistent tyrosine phosphorylation of cdc2 in K562 cells

Interferon-alpha (IFN-alpha) is a clinically useful cytokine for treatment of a variety of cancers, including chronic myelocytic leukaemia (CML). Most CML cells are sensitive to IFN-alpha; however, its biological effects on leukaemic cells are incompletely characterized. Here, we provide evidence that IFN-alpha induces a significant increase in the S phase population in human CML leukaemic cell line, K562, and that the S phase accumulation was augmented by sodium butyrate. In contrast, neither sodium butyrate alone, nor sodium butyrate plus IFN-gamma, affected the cell cycle in K562 cells. These data suggest that the effect of sodium butyrate depended upon IFN-alpha-mediated signalling. The ability of leukaemic cells to exhibit the S phase accumulation after stimulation by IFN-alpha plus sodium butyrate correlated well with persistent tyrosine phosphorylation of cdc2, whereas treatment with IFN-gamma plus sodium butyrate did not affect its phosphorylation levels. Considering that dephosphorylation of cdc2 leads to entry to the M phase, the persistent tyrosine phosphorylation of cdc2 may be associated with the S phase accumulation induced by IFN-alpha and sodium butyrate. In addition, another human CML leukaemic cell line, MEG-01, also showed the S phase accumulation after stimulation with IFN-alpha plus sodium butyrate. Taken together, our studies reveal a novel effect of sodium butyrate on the S phase accumulation and suggest its clinical application for a combination therapy with IFN-alpha, leading to a great improvement of clinical effects of IFN-alpha against CML cells.

Requirement of GATA-1 and p45 NF-E2 expression in butyric acid-induced erythroid differentiation

Butyric acid (BA) is known to induce overexpression of fetal hemoglobin and then erythroid differentiation. Therefore, BA is currently under clinical investigation as a potential therapy for the treatment of sickle cell disease and cancer. Nevertheless, the molecular mechanisms involved in BA-induced differentiation remain largely unknown. Previous reports have shown that BA-induced overexpression of erythroid genes occurred at the transcriptional level, suggesting the involvement of erythroid transcription factors. Here, we intend to demonstrate the requirement of GATA-1 and NF-E2 transcription factors in the BA-induced erythroid differentiation of human leukemic K562 cells. Time-course experiments showed that nuclear levels of GATA-1 and p45 NF-E2 proteins increased during BA treatment. Moreover, antisense oligodeoxynucleotides targeting either GATA-1 or p45 NF-E2 proteins inhibited both protein expression and BA-induced differentiation. In contrast, BA-induced cell growth inhibition was not affected. These results provide the first direct evidence for the requirement of GATA-1 and NF-E2 in BA-induced differentiation process.

Sodium butyrate stimulates PKC activation and induces differential expression of certain PKC isoforms during erythroid differentiation

Sodium butyrate (NaB) is an differentiation inducer currently under clinical investigation as a potential therapy for the treatment of sickle cell disease and prostate cancer. Though the biologic effects of this agent is well documented, its mechanism of action remains largely known. The mechanisms by which it transduces its signal to the nucleus is the subject of intense investigation in our laboratory. In this report, we demonstrate that NaB stimulates PKC activation by 3-fold and induces differential expression of several PKC isoforms. Notably, it upregulates PKC epsilon and downregulates PKC beta during erythroid differentiation. These findings suggest that certain PKC isoforms may play important roles in the signal transduction mechanisms of this agent leading to regulation of erythroid proliferation and differentiation.

Volatile fatty acid, metabolic by-product of periodontopathic bacteria, induces apoptosis in WEHI 231 and RAJI B lymphoma cells and splenic B cells

The ability of butyric acid, an extracellular metabolite from periodontopathic bacteria, to induce apoptosis in murine WEHI 231 cells, splenic B cells, and human RAJI cells was examined. The culture filtrate of Porphyromonas gingivalis, Prevotella loescheii, and Fusobacterium nucleatum, which contains high a percentage of butyric acid, induced DNA fragmentation in WEHI 231 cells. Volatile fatty acid, especially butyric acid, significantly suppressed B-cell viability in a concentration-dependent fashion. The DNA fragmentation assay indicated that butyric acid rapidly induced apoptosis in WEHI 231 cells (with 1.25 mM butyric acid and 6 h after treatment), splenic B cells (with 1.25 mM butyric acid), and RAJI cells (with 2.5 mM butyric acid). Incubation of WEHI 231 cells with butyric acid for 16 h resulted in the typical ladder pattern of DNA fragmentation and the apoptoic change such as chromatin condensation and hypodiploid nuclei. Cell cycle analysis implied that butyric acid arrested the cells at the G1 phase. The inhibitory assay suggested that butyric acid-induced apoptosis of WEHI 231 and splenic B cells was inhibited by W-7, a calmodulin inhibitor. These results suggest that calmodulin-dependent regulation is involved in the signal transduction pathway of butyric acid.