A study of adenosine 3':5'-cyclic monophosphate, sodium butyrate and cortisol as inducers of HeLa alkaline phosphatase

Nuclear translocation of the unliganded glucocorticoid receptor is influenced by membrane fluidity, but not A2AR agonism

Epidemiological evidence suggests that chronic consumption of caffeine, a non-selective antagonist of adenosine A_2AR receptors (A_2AR), can be neuroprotective in a number of age-related neurodegenerative disorders including Alzheimer's disease. A growing body of work shows that this neuroprotection may act via a synergistic interaction with the glucocorticoid receptor (GR) and its associated genetic response elements. Therefore, we hypothesized that A_2AR signaling may directly stimulate glucocorticoid receptor translocation via downstream signaling elements within the cell. Surprisingly, we found no effect of A_2AR agonism on GR translocation in the absence of steroid. As expected, membrane-bound dexamethasone was capable of stimulating full GR translocation, albeit at a slower rate. This non-liganded translocation was unaffected by A_2AR ligands, providing strong evidence that GR translocation occurs independently of activation of A_2ARs. To identify other potential mechanisms of translocation, membrane fluidity was increased significantly by benzyl alcohol, which also induced full nuclear translocation of the GR, but unlike the membrane-bound dexamethasone, benzyl alcohol did result in transcriptional upregulation of GR-dependent genes. Taken together, our data shows that the unliganded GR is sensitive to changes in membrane state and can be transcriptionally active.

An Activatable AIEgen Probe for High-Fidelity Monitoring of Overexpressed Tumor Enzyme Activity and Its Application to Surgical Tumor Excision

Monitoring fluctuations in enzyme overexpression facilitates early tumor detection and excision. An AIEgen probe (DQM-ALP) for the imaging of alkaline phosphatase (ALP) activity was synthesized. The probe consists of a quinoline-malononitrile (QM) core decorated with hydrophilic phosphate groups as ALP-recognition units. The rapid liberation of DQM-OH aggregates in the presence of ALP resulted in aggregation-induced fluorescence. The up-regulation of ALP expression in tumor cells was imaged using DQM-ALP. The probe permeated into 3D cervical and liver tumor spheroids for imaging spatially heterogeneous ALP activity with high spatial resolution on a two-photon microscopy platform, providing the fluorescence-guided recognition of sub-millimeter tumorigenesis. DQM-ALP enabled differentiation between tumor and normal tissue ex vivo and in vivo, suggesting that the probe may serve as a powerful tool to assist surgeons during tumor resection.

Modulation of lipid synthesis, apolipoprotein biogenesis, and lipoprotein assembly by butyrate

Short-chain fatty acids (SCFAs) are potent modulators of the growth, function, and differentiation of intestinal epithelia. In addition, high-fiber diets may protect against the development of atherosclerosis because of their cholesterol-lowering effects due, in large part, to SCFA production, liver sterol metabolism, and bile acid excretion. Although the small gut plays a major role in dietary fat transport and contributes substantially to plasma cholesterol and lipoprotein homeostasis, the impact of SCFAs on intestinal lipid handling remains unknown. In the present study, the modulation of lipid synthesis, apolipoprotein biogenesis, and lipoprotein secretion by butyrate was investigated in Caco-2 cells plated on permeable polycarbonate filters, which permit separate access to the upper and lower compartments of the monolayers. Highly differentiated and polarized cells (20 days of culture) were incubated for 20 h with 20 mM butyrate in the apical medium. In the presence of [14C]oleic acid, butyrate led to a significant reduction of secreted, labeled triglycerides (27%; P < 0.01) and phospholipids (25%; P < 0.05). Similarly, butyrate significantly decreased the incorporation of [14C]acetate into exported cholesteryl ester (49%; P < 0.005). As expected from these results, with [14C]oleic acid as a precursor, butyrate significantly (P < 0.05) diminished the delivery of radiolabeled chylomicrons and very low-density lipoproteins. In parallel, [35S]methionine pulse labeling of Caco-2 cells revealed the concomitant inhibitory effect of butyrate on the synthesis of apolipoproteins B-48 (28%; P < 0.05) and A-I (32%; P < 0.01). Collectively, our data indicate that butyrate may influence lipid metabolism in Caco-2 cells, thus suggesting a potential regulation of intestinal fat absorption and circulating lipoprotein concentrations.

Effect of sodium butyrate on the expression of genes transduced by retroviral vectors

We have studied the effects of sodium butyrate (NaBu) on the expression of genes transduced by retroviral vectors and stably expressed in two salivary gland-derived cell lines, A5-DAP and A5-BAG, established earlier. These cell lines were obtained by infecting A5 cells with the retroviral vectors DAP and BAG, respectively, and by selecting neomycin-resistant transduced cells. A5-DAP cells express human placental alkaline phosphatase (PLAP) and A5-BAG cells bacterial beta-galactosidase, both under the control of the viral long terminal repeat (LTR) enhancer-promoter. NaBu in the concentration of 2-8 mM inhibited the growth of A5-DAP cells, and induced the expression of heat-stable PLAP. These effects of NaBu were dose-dependent. Induction of PLAP in clones of A5-DAP cells that express different basal levels of the enzyme was not correlated with the relative inducibilty by NaBu. Exposure to 4 mM NaBu for 48 h increased the PLAP mRNA level by 31%. A5-DAP cells released, in a time-dependent manner, PLAP into the culture medium. Cells treated with NaBu released more PLAP than untreated cells in proportion to their elevated level of the enzyme. The parent A5 cells also express a low level of tissue non-specific type alkaline phosphatase, which was also induced by NaBu. NaBu inhibited the growth of A5-BAG cells also, and increased the beta-galactosidase level. These data indicate the genes transduced by retroviral vectors can be induced by NaBu, which most likely interacts with the viral LTR.

Induction of heat labile alkaline phosphatase by butyrate in differentiating endometrial cells

The addition of 2 mM sodium butyrate to monolayers enhances differentiation of Ishikawa endometrial cells. Cells from this cell line have been shown to enlarge and lift off the dish into dome structures over a period of 24-48 h in response to a factor in fetal bovine serum (FBS) [Fleming, 1995 J Cell Biochem in press]. When butyrate is added to monolayers, together with FBS, three- to fourfold higher numbers of differentiated structures, domes and predomes, can be counted. It had previously been shown [Holinka et al., 1986b] that estradiol induces heat stable placental alkaline phosphatase in Ishikawa cells. The addition of butyrate, on the other hand, results in a significant increase in levels of a heat labile alkaline phosphatase isozyme. The heat labile isozyme is also increased to some extent in cells stimulated to differentiate in response to FBS in the absence of butyrate. Differential inhibition by homoarginine and phenylalanine indicates that butyrate is inducing the liver-bone kidney isozyme that is found in endometrial glands in vivo.

Biology of human alkaline phosphatases with special reference to cancer

The current information on the cloning and sequencing of four alkaline phosphatase genes (PLAP, GCAP, IAP, TNAP) has been reviewed. It has provided insights into their evolutionary history and the mechanisms of catalysis and of uncompetitive inhibition. The oncodevelopmental biology of the germ cell and its excessive GCAP eutopic expression in neoplasia are noted, and there is reason to suggest that the enzyme may serve to guide migratory cells and to transport specific molecules such as fat and immunoglobulins across membranes. The hyperexpression of all four genes has been observed in various human tumors and in their cell lines, particularly cancers of the testis and ovary. The membrane APs have been investigated as targets for immunolocalization and immunotherapy.

Factors affecting nucleosome structure in transcriptionally active chromatin. Histone acetylation, nascent RNA and inhibitors of RNA synthesis

The nucleosomes of transcriptionally active genes can be separated from those of inactive genes by affinity chromatography on organomercury-agarose (Hg-agarose) columns. The basis for this separation is the difference in accessibility of the sulfhydryl groups of histone H3 and certain non-histone proteins in active and inactive chromatin. A new procedure distinguishing between different modes of binding of transcriptionally active nucleosomes to the Hg-agarose column has been applied to study several factors which might influence the binding reaction. Nucleosomes that bind to the column because of salt-labile associations with SH-reactive non-histone proteins, such as the high-mobility-group proteins, HMG-1 and HMG-2, were released by adding 0.5 M NaCl to the eluting buffer. The remaining nucleosomes, in which reactive histone H3 thiol groups can bind covalently to the organomercury, were then displaced from the column by 10 mM dithiothreitol. Both Hg-agarose-bound fractions contain the transcriptionally active DNA sequences of the cell, but inactive nucleosomes, such as those containing alpha-globin DNA, pass through the column. The histones of both Hg-agarose-bound fractions have significantly higher levels of acetylation than do histones of the unbound fraction, but the content of tri- and tetra-acetylated H3 and H4 is significantly higher in the nucleosomes with reactive H3 thiols. The rate of turnover of histone N-acetyl groups is also far greater in the Hg-agarose-bound nucleosomes than in the unbound nucleosomes. Although the overall levels of histone acetylation can be increased significantly by incubating HeLa cells in the presence of the deacetylase inhibitor, 5 mM sodium butyrate, this treatment has little if any effect on the total number of nucleosomes retained on the Hg-agarose column. However, the ability of Hg-agarose chromatography to detect localized changes in chromatin structure is evidenced by an 11-fold increase in the Hg-agarose binding of nucleosomes containing the DNA of the butyrate-inducible alkaline phosphatase gene, compared to the Hg-agarose-bound nucleosomes of control cells. Although nascent RNA chains are present in the Hg-agarose-bound nucleosomes released by dithiothreitol, binding of the SH-reactive nucleosomes to the Hg-agarose column is not dependent on the presence of proteins associated with nascent RNA chains, since binding does not decrease following removal of the nascent transcripts by ribonuclease treatment.(ABSTRACT TRUNCATED AT 400 WORDS)

Enhancement by theophylline of the butyrate-mediated induction of choriogonadotropin alpha-subunit in HeLa cells. I. Lack of correlation with cAMP

The glycoprotein hormone common alpha-subunit can be induced in HeLa and other nontrophoblastic tumor cell lines by sodium butyrate. This report demonstrates that production of alpha-subunit can be further modulated by theophylline, especially in conjunction with butyrate. This synergism was not observed with other phosphodiesterase inhibitors such as xanthine, caffeine, theobromine, or methylisobutylxanthine. Induction by a combination of the short chain fatty acid plus the methylxanthine results from a decrease in the lag time after effector addition as well as a change in the rate of subunit accumulation. The increase in alpha-subunit is correlated with an increase in the levels of alpha-subunit mRNA, suggesting that induction is manifest at a pretranslational stage. The production of alpha-subunit was only marginally affected in cultures treated with 8-Br-cAMP or forskolin. Intracellular levels of cAMP were increased approximately threefold by methylisobutylxanthine, twofold by theophylline, fourfold by forskolin, and about 50% by butyrate, yet significant induction was achieved only by butyrate and theophylline. Taken together, these data suggest that the synergism between butyrate and theophylline is not mediated by cAMP.

Synergistic actions of tetradecylthioacetic acid (TTA) and dexamethasone on induction of the peroxisomal beta-oxidation and on growth inhibition of Morris hepatoma cells. Both effects are counteracted by insulin

(1) The relation between the effects of the sulfur-substituted fatty acid analogue, tetradecylthioacetic acid (TTA), dexamethasone and insulin on enzyme induction and growth rate was studied in Morris hepatoma 7800 C1 cells in culture. (2) The activities of the cynanide-insensitive palmitoyl-CoA oxidase and palmitoyl-CoA hydrolase were induced about 2-fold by 50 microM TTA after 72 h of treatment. Catalase was less induced and NADPH-cytochrome-c2 reductase, glucose-6-phosphate dehydrogenase and lactate dehydrogenase were unaffected by the fatty acid analogue. (3) Dexamethasone (250 nM) induced the same enzymes as did TTA, but was a less efficient than 50 microM TTA. However, in combination their effects were more than additive, resulting in 4-7-fold increases. (4) Insulin (400 nM) counteracted the inductive effects of both TTA and dexamethasone on all enzymes except for lactate dehydrogenase, which was induced by the combination of all three compounds. (5) TTA inhibited the growth rate of the cells, and this effect was potentiated by dexamethasone and counteracted by insulin. (6) The enzyme inductions were similar in exponential and plateau phases of growth, indicating that these processes were independently affected by the three compounds.

Placental alkaline phosphatase-like isoenzymes produced by human gastric cancer cells

The human gastric cancer cell lines, MKN1 and SCH, were biochemically and biologically characterized according to the monophenotypic expression of placental alkaline phosphatase (PLAP)-like enzymes. The MKN1 cell line, derived from adenosquamous carcinoma, showed the same enzyme properties as the Regan isoenzyme, whereas the SCH cell line, derived from primary gastric choriocarcinoma, had properties identical with the Nagao isoenzyme. Regan isoenzyme activity expressed by MKN1 cells was stimulated by glucocorticoid and suppressed by retinoic acid. Both agents had no significant effect on SCH cells. On the other hand, Nagao isoenzyme activity expressed by SCH cells was stimulated by sodium butyrate, which had no stimulatory effect on MKN1 cells. Moreover, the PLAP-like activity of MKN1 cells showed no observable relationship to human chorionic gonadotropin (hCG)-producibility. Whereas expression of the Nagao isoenzyme by the SCH cell line is presumably a result of functional differentiation in the trophoblastic direction, that of the Regan isoenzyme by the MKN1 cell line is probably not. Perhaps the Regan isoenzyme is related to carcinogenesis.

Modulation of glycoprotein hormone alpha-subunit levels, alkaline phosphatase activity, and DNA replication by antimetabolites in HeLa cultures

Synthesis of the glycoprotein hormone common alpha-subunit and alkaline phosphatase (placental isozyme) has been examined in HeLa S3 cells. A variety of compounds that inhibit DNA synthesis lead to the increased production of both proteins. Experiments presented in this communication were undertaken to determine whether protein induction and DNA synthesis inhibition are coordinated. In general, nucleoside analogs and compounds that alter deoxynucleotide metabolism were good inducers of these ectopic products, whereas agents that altered DNA by intercalation, crosslinking, and covalent modification were poor inducers. The former class of effectors includes 5-bromo-2'-deoxyuridine, 5-fluoro-2'-deoxyuridine, 2'-deoxythymidine, 1-beta-D-arabinofuranosylcytosine, methotrexate, hydroxyurea, N-phosphonoacetyl-L-aspartic acid, and sodium butyrate; and the latter class of compounds includes ethidium bromide, acridine, bleomycin, mitomycin C, cesalin, macromomycin, and cis-diamminedichloroplatinum(II). A direct correlation between protein induction and DNA synthesis inhibition is unlikely based on the following observations: (i) for some effectors, the concentrations required to induce alpha-subunit and PAP were significantly different from those necessary to inhibit DNA synthesis; (ii) several agents inhibit DNA replication but do not enhance hormone or enzyme production; (iii) the kinetics of ectopic protein induction were similar for a number of inducers whereas the kinetics of DNA synthesis inhibition elicited by the same compounds were quite different. It is difficult from the data obtained, however, to rule out the possibility that inhibition of DNA synthesis may be required but is not sufficient for protein induction.

Two mechanisms of spermidine/spermine N1-acetyltransferase-induction

The changes in activity of spermidine/spermine N1-acetyltransferase (SAT), a rate-limiting enzyme in polyamine degradation, were investigated to understand the mechanism of the induction of this enzyme in bovine lymphocytes. The activity of SAT was induced by stimulation with phytohemagglutinin (PHA), calcium ionophore A23187, sodium n-butyrate, or methylglyoxal bis(guanylhydrazone) (MGBG). When the cells were treated with a combination of PHA with either MGBG or butyrate, the increase in SAT was synergistic. However, the treatment of cells with both PHA and A23187 did not cause more induction of the enzyme activity than the stimulatory effects of each agent alone. The elevation in SAT caused by PHA or A23187 was inhibited by the simultaneous addition of 25 microM H-7, a protein kinase C inhibitor; the induction of the enzyme activity by MGBG or butyrate was slightly enhanced in the presence of H-7. In cells treated with a high concentration of O-tetradecanoylphorbol 13-acetate, which results in the breakdown of protein kinase C, PHA and A23187 did not give the maximum response, and MGBG slightly enhanced the enzyme activity. Dibutyryl cyclic AMP inhibited PHA-induced enzyme activity, but it stimulated MGBG- or butyrate-induced activity. Exposure to PHA or A23187 but not to MGBG or butyrate significantly increased the ornithine decarboxylase activity and DNA synthesis. These results showed that there were two different mechanisms of SAT induction. One is dependent on protein kinase C. The other one is independent of protein kinase C and is enhanced by cyclic AMP.

Induction of alkaline phosphatase activity by synergistic action of dibutyryl cyclic adenosine monophosphate, prednisolone, butyrate and sodium chloride in cultured cells

Human urinary bladder carcinoma cells (JTC-32) retain a low alkaline phosphatase activity. Prednisolone or a hypertonic concentration of NaCl caused a moderate increase in the activity (10- to 15-fold of control), but dibutyryl cAMP or butyrate did not. Examination of the combined effect of these four agents revealed that they acted synergistically in any combination. When the cells were incubated with the four agents together, the enzyme activity increased 60- to 250-fold. Serum also contributed to this synergistic increase. These agents slightly inhibited cell growth and protein synthesis. The enzyme induction was completely inhibited by cycloheximide or actinomycin D. The synergistic effect of the four agents on the enzyme activity was also observed in other strains of carcinoma cells, human urinary bladder carcinoma cells (JTC-30) and monkey hepatocarcinoma cells (NCLP-6E). Thus, it is concluded that the coexistence of the four agents provides general and superior conditions for the induction of alkaline phosphatase in cultured carcinoma cells.

Differential regulation by butyrate and dibutyryl cyclic AMP of delta-opioid, alpha 2-adrenergic, and muscarinic cholinergic receptors in NCB-20 cells

Long-term treatment of NCB-20 cells with sodium butyrate resulted in a marked increase in the specific binding of [3H]D-Ala2,D-Leu5 enkephalin. This increase was concentration and time dependent, with an EC50 of about 480 microM and a maximal effect detected after 3-day treatment. At saturating concentration of butyrate (1 mM) the increase was three- to fourfold of the untreated control. Scatchard analysis revealed that the butyrate effect was due to an increase in the density of the opioid receptor binding sites. Butyrate also induced a smaller (about twofold) increase in the density of muscarinic cholinergic receptor binding assessed by using [3H]quinuclidinyl benzilate, whereas alpha 2-adrenergic receptor binding assessed by using [3H]clonidine was not significantly affected. The butyrate-induced opioid receptor binding could be totally abolished by the presence of cycloheximide, suggesting that the butyrate effect involves synthesis of the receptor protein. Butyrate treatment did not affect basal and prostaglandin E1-stimulated cyclic AMP levels but caused a three- to fourfold decrease in the IC50 of D-Ala2,D-Leu5 enkephalin for attenuating these cyclic AMP levels and approximately 25% increase in the maximal extent of attenuation. In contrast to the butyrate effect, long-term treatment of NCB-20 cells with 1 mM dibutyryl cyclic AMP induced an 80% decrease in the opioid and alpha 2-adrenergic receptor bindings and a 57% loss of muscarinic cholinergic receptor binding. This down-regulation of muscarinic cholinergic receptor binding sites was associated with a 35% decrease of carbachol-induced phosphoinositide breakdown, whereas the receptor up-regulation induced by butyrate was found to increase the carbachol response by about threefold. The differential regulation by butyrate and dibutyryl cyclic AMP suggests that the butyrate effect is mediated by a mechanism independent of intracellular cyclic AMP. The induction by butyrate of opioid-receptors and muscarinic cholinergic receptors in NCB-20 cells may provide a useful system for studying the regulation of gene expression of these receptor proteins.

Infantile hypophosphatasia: enzymatic defect explored with alkaline phosphatase-deficient skin fibroblasts in culture

Evidence that infantile hypophosphatasia may result from defective regulation of an intact structural gene for the tissue nonspecific (bone/liver/kidney) isoenzyme of alkaline phosphatase (TNSALP) was explored by studying physicochemical properties of ALP in sonicates of monolayers of cultured dermal fibroblasts from 7 patients (PT) and 5 age- and sex-matched control (CT) subjects. Both groups had low levels of ALP activity when assayed with 4-methylumbelliferyl phosphate substrate. The mean specific activity of ALP in the PT fibroblasts was markedly subnormal (Vmax less than 1% of CT), but apparently not from extracellular loss of enzyme, since defined medium had less ALP activity when conditioned by PT compared to CT cells. Although the mean Km for the sonicate ALP was similar for both groups at pH 10.1, pH optimum, thermal stability and response to several inhibitors appeared to be different. Nevertheless, it seemed that some TNSALP-like enzyme was present in the PT group. Exposure of cells in culture to 5-azacytidine and several putative inducers of ALP failed to increase the enzyme activity in either the PT or CT groups. Had the physicochemical properties of the constitutive (or inducible) ALP been the same in the PT and CT cell groups, the findings would have provided evidence for the generality of our previous observations in one patient which indicated that defective regulation of an intact structural gene for TNSALP could account for hypophosphatasia.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of differing concentrations of sodium butyrate on 1,2-dimethylhydrazine-induced rat intestinal neoplasia

The incidence, distribution, size, and histopathology of small and large bowel tumors induced by parenteral administration of 1,2-dimethylhydrazine were examined in rats given 1% or 2% sodium butyrate dissolved in drinking water. Although previous in vitro reports on colon cancer cell lines have suggested that sodium butyrate might have a role to play as a chemotherapeutic "differentiating agent," the results of this in vivo study indicate that sodium butyrate treatment enhanced the development of colonic neoplasia and was associated with increased fecal butyric acid concentrations. In contrast, no changes were seen in the incidence of small bowel tumors, luminal butyric acid concentrations, mucosal morphology, or brush-border enzyme activities (i.e., sucrase, alkaline phosphatase). This study suggests that dietary butyrate has an important, possibly indirect, regulatory role in carcinogenesis associated with an experimental animal model of colonic neoplasia.

Butyrate effects on normal and adapted hepatoma cells: morphological response and implications for vectoral cholesterol transport

The cell line 4IC6, adapted for growth in 6 mM sodium butyrate from Hepatoma Tissue Culture cells [R. Chalkley, and A. Shires (1985) J. Biol. Chem. 260, 7698-7704], exhibits a fourfold increase in histone acetate turnover. The 4IC6 cells were about 25 times more resistant to butyrate relative to the parental cell line as measured by cloning efficiency. This line also maintains a flatter and more extended morphology when growing in the presence of 6 mM sodium butyrate relative to the parental line. Both cell lines maintain similar intracellular butyrate levels and incorporate [1-14C]butyrate into lipids to similar extents when incubated in medium containing high levels of the fatty acid. These results show that 4IC6 cells have not attained butyrate resistance through acquiring the ability to metabolize butyrate more efficiently or in a significantly different manner when compared with the parental cell line. The membrane lipid composition was nearly identical between the two cell types. Thus the different morphologies exhibited by each cell line were not a consequence of altered membrane lipid composition. The resistant line, 4IC6, maintains about 10-fold higher cholesterol ester levels and half the level of triglycerides found in the parental line. The butyrate-resistant cells also synthesize cholesterol at about a 1.8-fold higher rate than do the parental cells. This difference in de novo synthesis is reflected by a difference of a similar factor in the amount of radioactive cholesterol the two cell lines accumulate over 12 generations. These results are discussed with respect to models for equilibration of serum lipoprotein-derived and newly synthesized cholesterol.

Regulation of alkaline phosphatase activity in rat hepatoma cells. Effects of serum proteins, cycloheximide, actinomycin D, chloroquine, dinitrophenol and potassium cyanide

Alkaline phosphatase activity in rat hepatoma cells (R-Y121B) cultured in a monolayer at 0.5% serum was enhanced by serum, bovine serum albumin, casein and gamma-globulin, but ovalbumin, polyvinylpyrrolidone, dexamethasone, insulin and dibutyrylcyclic AMP showed little effect on alkaline phosphatase activity. In addition, cycloheximide, actinomycin D, chloroquine, dinitrophenol and potassium cyanide also increased the enzyme activity, although the incorporation of [14C]leucine into cellular proteins was almost completely inhibited in the presence of these cytotoxic substances. When R-Y121B cell homogenates were incubated at 37 degrees C, alkaline phosphatase activity increased in a pH-dependent manner: the maximal increase was observed at pH 7.1. The magnitudes of the increase differed among cell homogenates and a 4- to 10-fold increase was observed. Alkaline phosphatase in R-Y121B cells was apparently heat-stable, but that in the cells obtained from various treatments was heat labile and the latter activity decreased to less than 50% of the initial activity after 15 min of incubation at 56 degrees C. Alkaline phosphatase in the control and also in the treated cells was more sensitive to L-homoarginine than L-phenylalanine. The Lineweaver-Burk plot showed that the increases in the enzyme activity were accompanied by changes not only in V but also in Km for alkaline phosphatase reaction. Finally, it has been suggested that the increases in alkaline phosphatase activity under various conditions are due to the conversion of the molecule with a low enzyme activity to the molecule with a high enzyme activity in R-Y121B cells.

Influence of sodium butyrate on HeLa cell morphology and proliferation

The effect of one-week exposure to sodium butyrate on HeLa S3 cell cultures was studied with special regard to influence on prekeratin synthesis, by comparison to cultures similarly treated with the known proliferation inhibitor hydroxyurea, and not treated. Like hydroxyurea, sodium butyrate inhibited cell proliferation to a considerable degree, but accounted additionally for an increase in membrane-bound alkaline phosphatase activity, cellular prekeratin synthesis, tonofilament number, and filament bundle formation. These phenomena unequivocally indicate that sodium butyrate acted as a specific stimulator of Hela (epithelial) cell differentiation. Similar differentiation phenomena can be observed during early spontaneous keratinization of the stratified horny epithelium.

Synergistic stimulation of alkaline phosphatase activity in bovine aortic endothelial cells grown in the presence of retinoids and glucocorticoids

Low concentrations of retinol (10 nM-10 microM) and dexamethasone (0.1 nM-1.0 microM) elevated activity of alkaline phosphatase (E.C. 3.1.3.1) in bovine endothelial cells in culture. The effect was apparent after 48 hr of growth in the presence of either of the two compounds, prior to any growth stimulatory effects. A synergistic stimulation of alkaline phosphatase was achieved in the presence of both retinol and dexamethasone implying different mechanisms of induction. Retinoic acid and retinyl acetate also elevated alkaline phosphatase but the retinol analogue reduced in the side chain (perhydroretinol) was inactive. The ability of steroids to elevate alkaline phosphatase activity was associated with the structure commonly required for glucocorticoid activity; however, competitors for the steroid receptor binding failed to prevent the elevation by dexamethasone or the synergism in the presence of retinol and dexamethasone.

An in vitro cytotoxicity test to predict the ocular irritation potential of detergents and detergent products

Two in vitro cytotoxicity procedures, the measurement of cell-membrane integrity using fluorescein diacetate and ethidium bromide, and the quantitation of the release of a cell-membrane-bound enzyme, alkaline phosphatase, were used to assess the cytotoxicity of a range of cationic, anionic and nonionic detergents. The in vitro results were compared with the in vivo irritancy of these compounds in the rabbit eye. Although in general the decreasing order of potency of cationic, anionic and nonionic detergents was similar in vivo and in vitro, there were some apparent anomalies which may be due to the differing penetration characteristics of the detergents, as indicated by electrical impedance measurements of the isolated cornea. The study was extended to an examination of the cytotoxicity of a range of completely soluble, detergent-based formulations in a suspension culture of mouse fibroblasts. In this case the in vitro results correlated more closely with those from the in vivo tests.

Effect of sodium butyrate on human breast carcinoma (MCF-7) cellular proliferation, morphology, and CEA production

Sodium butyrate is a potent inducer of leukemic cell differentiation. This agent also affects epithelial cell proliferation and gene expression. The present study demonstrates that sodium butyrate slows proliferation and induces morphologic changes in human MCF-7 breast carcinoma cells. The results also demonstrate that butyrate-treated MCF-7 cells have enhanced expression of carcinoembryonic antigen. These effects are related to butyrate concentration and duration of exposure. The present findings may provide a model for studying maturation of human breast cancer cells.

Inducibility of heat shock polypeptides in cells containing hyperacetylated histones

We have examined the effect of sodium butyrate on the levels of histone acetylation, the pattern of protein synthesis and the inducibility of heat shock polypeptides (hsps) in cultured trout fibroblasts. Maximal levels of histone acetylation are achieved upon treatment of these cells with 5 mM butyrate for 24 h. No significant changes in the pattern of protein synthesis, as detected by two-dimensional gel electrophoresis, are apparent under these conditions, although changes in the levels of three polypeptides are seen at shorter times of exposure to butyrate. Heat shock polypeptides are inducible at normal levels in butyrate-treated cells. This is in contrast to the ability of butyrate to inhibit the activation of steroid-inducible genes in some systems.

Effects of sodium butyrate on growth and cell-cycle kinetics of cultured rabbit articular chondrocytes

The sodium salt of n-butyric acid was found to inhibit the growth of asynchronous cultures of rabbit articular chondrocytes. This inhibitory effect was dose-dependent between 1 mM and 5 mM, reversible, and accompanied by volume enhancement and modification of cellular morphology. Flow-cytometric analysis showed that drug exposure led to a slowing-down of the cell-cycle progression; after 1 day's exposure, cells accumulated in G1, and after 2 or 3 days' treatment, in G2, without a blockage in M; the increase of cells in G2 was in fact due to an enhancement of binculeated cells. The treated cells had an increased RNA content. Articular chondrocytes seem to be target cells for sodium butyrate and therefore it represents a valuable biological tool for studying the mechanisms of their growth regulation.

Glucose requirement for induction by sodium butyrate of the glycoprotein hormone alpha subunit in HeLa cells

Butyric acid produces multiple effects on mammalian cells in culture, including alterations in morphology, depression of growth rate, increased histone acetylation, and modified production of various proteins and enzymes. The latter effect is exemplified by the induction in HeLa cells of the glycoprotein hormone alpha subunit by millimolar concentrations of the fatty acid. This report demonstrates that increased subunit accumulation in response to sodium butyrate is strikingly dependent on the presence of glucose (or mannose) in the growth medium. In contrast, basal levels of subunit synthesis are only marginally affected when the culture medium is supplemented with one of a variety of hexoses. An increase in the accumulation of HeLa alpha does not occur in medium containing pyruvate as the energy source, and sustained induction requires the simultaneous and continued presence of both glucose and butyrate. The effects of butyrate on HeLa cell morphology and subunit induction can be separated, since the latter is glucose-dependent while the former is not. Failure of butyrate to induce alpha in medium containing pyruvate does not result from restricted subunit secretion, since the levels of intracellular alpha are not increased disproportionately relative to those in the medium. The hexoses which support induction of HeLa alpha (glucose greater than or equal to mannose greater than galactose greater than fructose) are identical to those which have been shown previously to stimulate the glucosylation of lipid-linked oligosaccharides and enhance the synthesis of certain glycoproteins. Labeling of various glycosylation intermediates with [3H]mannose indicates that in glucose medium there is a decrease in the level of radioactivity associated with both dolicholpyrophosphoryl oligosaccharide and cellular glycoproteins and a concomitant increase in the fraction of label recovered in secreted glycoproteins. Butyrate also causes a decrease in [3H]mannose-labeled cellular glycoproteins and an increase in tritiated extracellular glycoproteins, particularly in glucose medium. Likewise, glucose stimulates the incorporation of [3H]glucosamine into immunoprecipitable alpha subunit relative to the bulk of HeLa-secreted glycoproteins, and this is further enhanced by butyrate. However, as demonstrated by lectin chromatography of conditioned media, a nonglycosylated subunit does not accumulate in pyruvate medium, either in the absence or presence of butyrate.(ABSTRACT TRUNCATED AT 400 WORDS)

Attachment culture of human retinoblastoma cells: long-term culture conditions and effects of dibutyryl cyclic AMP

Cells from the Y-79 human retinoblastoma line were successfully grown as long-term monolayer cultures in serum-supplemented or serum-free, defined medium after pretreatment of the substrate with poly-D-lysine and fibronectin. A significant proportion of the cells differentiated morphologically in serum-free, defined medium as well as in serum-containing medium after treatment with dibutyryl cyclic AMP (dbcAMP). In the defined medium, approximately 30% of the cells showed development of long, ramifying processes, consistent with putative neuronal differentiation. Addition of dbcAMP in the defined medium resulted in an increasing number of differentiating cells (up to 50%); scattered flat cells were observed as well. Treatment of serum-supported cultures with dbcAMP resulted in a larger proportion (10%) of flat cells. Attempts to differentiate the cells with retinoic acid were unsuccessful. These results show that Y-79 cells can grow in attachment culture and differentiate into at least two distinct morphological cell types as well as offering an interesting system for studying the factors controlling growth and differentiation in human tumor cells in vitro.

Effects of sodium butyrate and dimethylsulfoxide on human pancreatic tumor cell lines

The effects of 1 mM sodium butyrate or 2% dimethylsulfoxide (DMSO) on three human pancreatic tumor cell lines were examined. The cell lines tested were MIA PaCa-2, PANC-1 and CAPAN-1. Both butyrate and DMSO inhibited the ability of all three lines to form colonies in soft agar. These results suggest that the use of these agents provides a model system for the study of the molecular changes involved in human pancreatic cancer. In butyrate all the cell lines showed a marked increase in cellular levels of alkaline phosphatase, while growth in DMSO led to a reduction in most cases. DMSO caused a rapid reduction in the attachment of all three cell lines to collagen substrates, while butyrate had no effect. These results illustrate the fact that although both butyrate and DMSO appear to greatly reduce the parameters correlated with tumorigenicity of human pancreatic cancer cells, the mechanisms involved may be very different.

Effects of prednisolone and butyrate on agglutinability of HeLa cells by concanavalin A

Agglutinability by concanavalin A was measured with HeLa65 cells grown with prednisolone or sodium butyrate, 2 compounds that increase the activity of the carcinoplacental form of alkaline phosphatase, an enzyme localized in membranes. Prednisolone enhanced concanavalin A agglutination approximately 3-fold while sodium butyrate had no effect.

Preferential alkaline phosphatase isoenzyme induction by sodium butyrate

SW-620, a continuous cell line derived from a poorly differentiated human colon carcinoma, produces two alkaline phosphatases. Under basal conditions the heat-stable, term-placental is the major isoenzyme and the heat-labile, liver/bone/kidney form represents a minor component. Exposing SW-620 cells to sodium butyrate causes induction of increased levels of activity accompanied by a striking shift in isoenzyme distribution not observed heretofore. The activity increase is accounted for entirely by augmentation of the liver/bone/kidney isoenzyme, with the term-placental form not being affected. Two other known alkaline phosphatase inducers, prednisolone and hyperosmolality, do not influence specific activity and isoenzyme distribution. The preferential induction of the liver/bone/kidney form of alkaline phosphatase in SW-620 cells may reflect a butyrate-elicited expression of a more differentiated state.

Measurement of biosynthetic rates and intracellular transit times for a cell-surface membrane glycoprotein, alkaline phosphatase in HeLa cells

The techniques for measurement of biosynthetic rates and intracellular transit times of an integral membrane protein isoenzyme have now been validated. Thus, induction of placental alkaline phosphatase in cultured HeLa cells by prednisolone and by butyrate is shown to result in its increased biosynthesis as measured by uptake of [35S]methionine into immunoprecipitated cell-surface placental alkaline phosphatase. The cell-surface placental alkaline phosphatase is liberated from the cells by proteolytic cleavage by bromelain, which results in a decrease of the placental alkaline phosphatase subunit mass from 64,000 to 62,000 daltons. The time of transit of new placental alkaline phosphatase molecules from their ribosomal site of synthesis to their terminal cell-surface, bromelain-sensitive site is approximately 55 min. This system may be useful in studies of regulation of intracellular protein processing and transport to the cell surface of proteins destined to become integral membrane proteins.

Effect of media composition on the induction of chorionic gonadotropin by sodium butyrate in HeLa cells

Production of the glycoprotein hormone alpha-subunit by HeLa cells and its induction by sodium butyrate are dependent on the choice of culture medium. Under identical growth conditions it was found that subunit synthesis in the presence of butyrate was highest in RPMI 1640, lowest in Medium 199 (M199), and intermediate in minimum essential medium (MEM) and Waymouth's MB 752/1. Cell growth was similar in all media examined and was retarded in the presence of butyrate. Alkaline phosphatase activity was also lower in M199 than in RPMI 1640, although, in general, the magnitude of this difference was less than that for the hormone subunit. Incorporation of [1-14C]butyrate by HeLa cells was similar in both M199 and RPMI 1640, indicating that uptake and metabolism of the fatty acid were not significantly different under these conditions. In the presence of 3 mM butyrate, mixtures of RPMI 1640 and M199 gave intermediate levels of alpha-subunit and alkaline phosphatase compared to each medium alone. Intracellular levels of alpha-subunit as well as that of the culture medium were reduced in M199 compared to RPMI 1640 indicating that synthesis rather than secretion was altered.

Synergistic induction of alkaline phosphatase in colonic carcinoma cells by sodium butyrate and hyperosmolality

Exposing HT-29 cells to the combination of two inducers of intestinal alkaline phosphatase, sodium butyrate and hyperosmolality, causes a synergistic (over 1000-fold) increase in specific activity. Evidence is presented showing that enzyme induction is reversible; the half-life of the induced activity is approximately 30 h. Preinduction by butyrate or by hyperosmolality does not prime the cells so as to respond synergistically when subsequently exposed to hyperosmolality or butyrate, respectively. This study demonstrates that when applied in combination, the effect on gene expression by one alkaline phosphatase inducer is amplified by the other.

Expression of the alpha subunit of human chorionic gonadotropin is specifically correlated with tumorigenic expression in human cell hybrids

The expression of HeLa parent phenotype protein markers, the alpha subunit of human chorionic gonadotropin and placental alkaline phosphatase isoenzymes, has been evaluated in paired tumorigenic and nontumorigenic HeLa-fibroblast human cell hybrids. Both of these proteins have been used clinically as markers of malignancy. The results showed that both are expressed in the hybrids. Expression of the gonadotropin subunit in the hybrids is specifically correlated with tumorigenicity; the placental alkaline phosphatase isoenzyme showed no such correlation and was expressed in both tumorigenic and nontumorigenic hybrids.

Effects of sodium butyrate, a new pharmacological agent, on cells in culture

Sodium butyrate, at millimolar concentrations, when added to cell cultures produces many morphological and biochemical modifications in a reversible manner. Some of them occur in all cell lines. They concern regulatory mechanisms of gene expression and cell growth: an hyperacetylation of histone resulting from an inhibition of histone deacetylase and an arrest of cell proliferation are almost constantly observed. Some other modifications vary from one cell type to another: induction of proteins, including enzymes, hormones, hemoglobin, inhibition of cell differentiation, reversion of transformed characteristics of cells to normal morphological and biochemical pattern, increase in interferon antiviral efficiency and induction of integrated viruses. Most if not all these effects of butyrate could result from histone hyperacetylation, from changes in chromatin structures as measured by accessibility to DNases and from modifications in cytoskeleton assembly. We do not know at the present time whether butyrate acts on a very specific target site in cell or if it acts on several cell components.

Alkaline phosphatase activity in cultured meningioma cells

The specific activity of alkaline phosphatase in cultured human meningioma cells varies over a relatively wide range. There is no correlation between the levels of activity and the histological type of meningioma from which the cultures were derived. The enzyme is heat-labile and is strongly inhibited by L-homoarginine, levamisole, and 1-bromotetramisole, but unaffected by L-phenylalanine and L-phenylalanyl-glycylglycine. These findings indicate that meningioma cells synthesize the liver/bone/kidney form of alkaline phosphatase. In contrast to cultures derived from pituitary adenomas, glioblastomas, and astrocytomas in which prednisolone and/or sodium butyrate elicit a manifold increase of alkaline phosphatase activity, with meningioma cells the hormone causes only a slight augmentation in specific activity, and the fatty acid is ineffective. As with other cells producing the liver/bone/kidney enzyme form, no increase in activity occurs in meningioma cells growing in hyperosmolar medium.

Placental alkaline phosphatase isoenzyme expression by the non-HeLa DoT cervical-carcinoma cell line

Expression of the oncodevelopmental protein, placental alkaline phosphatase, was observed in DoT cells, an epidermoid cell line derived from cervical carcinoma. Under normal conditions of growth in vitro, biochemical inhibition, cytochemical and immunological studies revealed that these cells express the term-placental (Regan) isoenzyme. Thus alkaline phosphatase activity was observed to be heat-stable and inhibited by L-phenylalanine. These properties, supported by immunoelectrophoretic analysis using antisera specific for liver, intestinal or term-placental isoenzymes, identified the isoenzyme as placental type. DoT cells treated with prednisolone (1 microgram/ml) increased total alkaline phosphatase specific activity. This activity was also identified as term-placental phosphatase isoenzyme. On the other hand, treatment of the same cells with sodium butyrate (1 mM) did not induce increased activity of the term-placental isoenzyme, an unexpected observation. As a result of these studies, DoT cells are proposed as a representative cell line for studies of the regulation of oncodevelopmental gene expression in human tumour cells of cervical origin.

Selective inhibition by sodium butyrate of glucocorticoid-induced tyrosine aminotransferase synthesis in hepatoma tissue-cultured cells

Sodium butyrate in a 5 mM concentration prevents the induction of tyrosine aminotransferase in hepatoma culture cells, without affecting the basal level of the enzyme. This effect is reversible immediately after the removal of butyrate, or after a lag, if butyrate was present for more than 2 h. Neither the amount of cellular RNA nor the rate of total RNA synthesis were affected by sodium butyrate. Furthermore, butyrate does not inhibit protein synthesis: [35S]methionine incorporation into proteins, measured in a reticulocyte lysate system, shows no significant difference between the translation capacity of the RNAs from butyrate-treated cells and from dexamethasone-induced or uninduced cells. Nevertheless, when tyrosine aminotransferase was isolated from the translation products by its specific antiserum and analyzed by gel electrophoresis, we observed that the amount of the enzyme synthetized in the presence of RNAs from dexamethasone/butyrate-treated cells was strongly diminished relative to that synthesized in the presence of RNA from dexamethasone-induced cells. These experiments indicate that the treatment of the cells with butyrate decreases the activity of the specific messenger RNA for tyrosine aminotransferase to a level close to the basal level.

Alkaline phosphatase protein increases in response to prednisolone in HeLa cells

Quantification of term-placental alkaline phosphatase isoenzyme protein in HeLa TCRC-1 cells grown in the presence and absence of prednisolone indicates that there is a net increase in amount of enzyme-specific protein in prednisolone-stimulated cells. In a similar analysis of HeLa D98AH2 cells, prednisolone treatment causes the appearance of term-placental alkaline phosphatase protein and the loss of the intestinal isoenzyme protein. These results support the interpretation that the response of these cells to corticosteroids is the net accumulation of alkaline phosphatase protein rather than the modification of pre-existing enzyme to a more active state.