Alkaline phosphatase content and the effects of prednisolone on mammalian cells in culture

Enzyme-Instructed Self-Assembly for Spatiotemporal Profiling of the Activities of Alkaline Phosphatases on Live Cells

Alkaline phosphatase (ALP), an ectoenzyme, plays important roles in biology. But there is no activity probes for imaging ALPs in live cell environment due to the diffusion and cytotoxicity of current probes. Here we report the profiling of the activities of ALPs on live cells by enzyme-instructed self-assembly (EISA) of a D-peptidic derivative that forms fluorescent, non-diffusive nanofibrils. Our study reveals the significantly higher activities of ALP on cancer cells than on stromal cells in their co-culture and shows an inherent and dynamic difference in ALP activities between drug sensitive and resistant cancer cells or between cancer cells with and without hormonal stimulation. Being complementary to genomic profiling of cells, EISA, as a reaction-diffusion controlled process, achieves high spatiotemporal resolution for profiling activities of ALPs of live cells at single cell level. The activity probes of ALP contribute to understanding the reversible phosphorylation/dephosphorylation in the extracellular domains that is an emerging frontier in biomedicine.

Investigation and verification of a bioluminescent biosensor for the quantitation of ara-CTP generation: a biomarker for cytosine arabinoside sensitivity in acute myeloid leukaemia

A novel whole cell bacterial biosensor, which emits light in response to the active metabolite of cytosine arabinoside (ara-C, cytarabine), ara-CTP, has been investigated and verified. The biosensor has been formulated as an ex vivo assay, designed for peripheral blood or bone marrow cells, which can produce a clinical result within a working day. The nucleoside analogue ara-C is a key agent for treatment of acute myeloid leukaemia (AML); treatment decisions are made rapidly with AML, patients often receiving same-day commencement of chemotherapy. Currently no rapid predictive test is available to select appropriate therapy for patients prior to treatment. Experiments were designed to determine optimal assay conditions using leukaemic cell lines. We observed a significant increase (~15 fold) in bioluminescence signal compared to control after 8-h incubation of the biosensor with ara-C. This corresponded to a >2-log increase in light output per bacterial cell. Interestingly, bioluminescence conferred a survival advantage to the bacteria following ara-C treatment. The assay is sensitive (lower limit of quantitation of 0.05 µM), selective, accurate (≤ 15% RE) and precise (≤ 15% coefficient of variation) over a linear concentration range of ara-CTP (0.05-0.5 µM), and detection is independent of reaction volume. Recovery of added standard was tested using ex vivo patient leukaemic cells (n=5). Stability studies on lyophilized bacterial biosensor were performed to ensure maintenance of performance over 12 months. The biosensor assay could be invaluable to the clinician, assisting with treatment selection, and potentially mitigating the risks of resistance and toxicity observed with this drug.

Alkaline phosphatase activity in human colostrum as a valuable predictive biomarker for lactational mastitis in nursing mothers

AIMS

Biochemical investigations have shown that an indigenous milk enzyme - alkaline phosphatase (ALP) - which is detectable in the lactocytes, plays a very important diagnostic role in clinical medicine, since its activity varies in different tissues and serves as a specific indicator of disease states. The purpose of this study was to evaluate ALP activity in human colostrum as a possible early predictive biomarker for lactational mastitis in nursing mothers.

PATIENTS & METHODS

During a period from May to July 2010, a total of 60 healthy nursing mothers were recruited for this study.

RESULTS

The mean level of colostrum ALP activity from the affected breasts was significantly higher when compared with ALP activity from the contralateral asymptomatic as well as 'healthy' breasts (p < 0.01).

CONCLUSION

Determining ALP activity in colostrum could be a valuable biochemical marker for an early prediction of mastitis in nursing mothers.

The involvement of hypophyseal-gonadal and hypophyseal-adrenal axes in arsenic-mediated ovarian and uterine toxicity: modulation by hCG

This study evaluated the involvement of hypophyseal-gonadal and hypophyseal-adrenal axes as a possible mechanism of sodium arsenite toxicity in ovary and uterus by the coadministration of hCG. Subchronic treatment of 0.4 ppm of sodium arsenite/(100 g body weight day) via drinking water for seven estrous cycles significantly suppressed the plasma levels of leutinizing hormone, follicle-stimulating hormone, and estradiol along with sluggish ovarian activities of Delta(5),3beta-hydroxysteroid dehydrogenase and 17beta-hydroxysteroid dehydrogenase followed by a reduction in gonadal tissue peroxidase activities in mature female rats at diestrous phase. Noticeable weight loss of the ovary and uterus along with prolonged diestrous phase and increased deposition of arsenic in the plasma and in these reproductive organs were also demonstrated following the ingestion of arsenic. Follicular atresia and thinning of the uterine luminal diameter were evident after sodium arsenite treatment. Effective protection of gonadal weight loss, suppressed ovarian steroidogenesis, and altered ovarian and uterine peroxidase activities were noticed when 1.0 IU hCG/(100 g body weight day) is given in arsenic-intoxicated rats. Normal estrous cyclicity was restored toward the control level after hCG coadministration, though the elimination of elementary arsenic from the plasma and gonadal tissues was impossible. A significant recovery in the restoration of ovarian and uterine histoarchitecture was prominent after hCG treatment. Adrenal hypertrophy and steroidogenic arrest of the adrenal gland along with altered level of brain monoamines in the midbrain and diencephalons following arsenic intoxication were also ameliorated after hCG coadministration.

Heritability and control of differentiated function in cultured cells

An established tissue culture cell line which retains a differentiated function in vitro is described. The cell line is of connective tissue origin, and its characteristic property is the synthesis and secretion of acid mucopolysaccharides, mainly hyaluronic acid. This differentiated cell function, the activity of which depends on continuous gene action, was found to be possessed by each of eleven clonal substrains, and is therefore a genetically heritable cell character. Rate of acid mucopolysaccharide biosynthesis falls sharply under the influence of the environmental conditions existing in crowded cultures, and this rate also declines if protein synthesis is directly inhibited with puromycin. Environmental modification of a differentiated product of gene action is thus illustrated in this study.

METABOLIC CONTROLS IN CULTURED MAMMALIAN CELLS

A number of apparently unrelated factors are known to have a profound effect on the metabolism of cultured mammalian cells; and some of these may be operative as metabolic controls in the whole animal as well. The more complete exploration of (i) homotypic and heterotypic cellular interactions, (ii) the spontaneous transformations sometimes observed in cultured cells, (iii) the mode of action of cytotoxic agents, (iv) the multiple metabolic effects of viral infection, and (v) the conditions necessary for the maintenance of specialized function in cultured cells, can be expected to throw light on the basic mechanisms underlying such complex processes as differentiation, senescence, and cancer.

Chlorpromazine and other psychoactive drug induced alterations of a membrane bound enzyme in rat brain

Psychoactive drugs like chlorpromazine (CPZ), imipramine, lithium and amphetamine in one way or another affect behaviour. The drug responses are presumably mediated by inducing a change in the activity of membrane bound enzymes. CPZ is very potent in inhibiting the alkaline phosphatase activity in rat brain. The combined effect of CPZ with other drugs shows that CPZ and imipramine together inhibit the enzyme activity significantly greater than the individual inhibition either by CPZ or by imipramine alone. Effective inhibition of the alkaline phosphatase activity with a single drug or combined drugs may lead to a change in neuronal permeability through glucocorticoids thereby affecting mood.

Characterization of glucocorticoid inhibition of antigen-induced inositolphosphate formation by rat basophilic leukemia cells: possible involvement of phosphatases

The suppressive effect of glucocorticoids (GC) upon antigen-induced phosphatidylinositol phospholipase C (PI-PLC) activity and inositol phosphate formation by rat basophilic leukemia cells (RBL-2H3) has been characterized. Addition of antigen for a period of 1-30 min enhanced production of [3H]inositol monophosphate (IP1), inositol 1,4-bisphosphate (IP2) and inositol 1,4,5-trisphosphate (IP3) by about 5-10-fold. Pretreatment with hydrocortisone (HC) reduced formation of the various inositol phosphates (IPs) and degradation of phosphatidylinositol 4,5-bisphosphate (PIP2) by an average of 50%. Maximal inhibition of hydrolysis of PIP2 and reduction in stimulation of IP3 formation was reached after 4 h of preincubation with 2.10(-6) M of HC. Cycloheximide and RU486, a GC receptor antagonist, completely prevented the inhibitory effect of HC on IP formation. Other GC, dexamethasone (DEX) and triamcinolone (each at 2.10(-7) M) markedly suppressed antigen induced IP3 production, while aldosterone and sex steroids such as estradiol and progesterone (each at 2.10(-6) M) were virtually inactive. Antigen-stimulated phosphorylation of a 18 kDa and other proteins was inhibited by about 60% following pretreatment with the GC. This inhibition was in turn prevented by cycloheximide. DEX also doubled the activity of cellular acid phosphatase activity. The results suggest that the inhibitory effect of GC is specific, receptor-mediated, dependent on protein synthesis and possibly mediated by protein phosphatase activity.

Modulation of alkaline phosphatase activity in alveolar type II like cells

Alveolar type II like cells (ALT II) represent a small subpopulation of alveolar type II cells, which is able to proliferate, can be passaged and possess many characteristics of differentiated adult type II cells. A correlation was found between the growth and development of ALT II cells in culture and their alkaline phosphatase activity. Unlike alveolar type II cells, which lose the activity in culture, ALT II cells regain the activity and maintain it for a long culture period. Quantitative histochemical analysis of the stained cells indicate that 80% of the cells at days 15-20 in culture are alkaline phosphatase positive. Inhibition studies indicate that alkaline phosphatase from ALT II cells and freshly isolated type II cells were similar. The inhibition of ALT II alkaline phosphatase by L-levamisole and its heat stability are similar to that of the bone enzyme and differ from the intestinal enzyme. Alkaline phosphatase expression is considered part of the differentiated phenotype of these cells. Therefore, the presence of this enzyme in ALT II cells adds support to the notion that these cells maintain many aspects of mature alveolar type II 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.

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.

'Superactivation' of alkaline phosphatase activity by cycloheximide in rat hepatoma cell cultures

We have found that rat hepatoma cells (R-Y121B) retain alkaline phosphatase activity, and that this enzyme activity is increased by cycloheximide. Actinomycin D also increased the enzyme activity. This increase due to actinomycin D was partially inhibited by cycloheximide. The characteristics of alkaline phosphatase of the cells treated or untreated with cycloheximide or actinomycin D were similar to each other; they were heat labile and the enzyme reaction was strongly inhibited by L-homoarginine, but weakly by L-phenylalanine. The increase in alkaline phosphatase activity with cycloheximide has been termed a 'superactivation' of alkaline phosphatase.

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.

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.

Unbalanced growth and cell death in HeLa S3 cultures treated with DNA synthesis inhibitors

Flow cytometry indicated that significant amounts of dsRNA were accumulated in HeLa S3 cells blocked at or near G1/S boundary by hydroxyurea (HU) or excess thymidine (TdR). The dsRNA/DNA ratio increased in these cells in a manner characteristic of unbalanced cell growth. In HU-treated cells, dsRNA content was maximal 16 hours after addition of the drug and did not change significantly during the next 24 hours. The DNA content in blocked cells increased by 10%. Cell viability assessed by colony formation in soft agar decreased exponentially in HU-treated cultures after 16 hours of incubation. Correlation between loss of cell viability and rate of cell proliferation after removal of HU was observed, as determined by cell count and analysis of cell cycle progression. In TdR-treated cultures cells slowly progressed into mid S-phase during 40 hours and dsRNA accumulation continued during this period. Cell viability was not significantly affected by treatment with excess TdR, indicating that unbalanced growth per se, as measured by dsRNA accumulation, is not lethal for the cells. After reversal of DNA synthesis inhibition by removal of the drug, cells treated with HU for 16 hours of TdR for 16--24 hours promptly progressed through the cell cycle. This progression was accompanied by accumulation of significant amounts of dsRNA. As a result, cells in G2 phase had a very high dsRNA content leading to retention of the unbalanced condition (increased dsRNA/DNA ratio) in the daughter cells. It is suggested that dsRNA accumulation in the cell is controlled to a certain degree by cell progression through the S phase. This type of control, evidently, was reflected in limited dsRNA accumulation in the cells blocked at or near G1/S border, in continuous dsRNA accumulation in the cells slowly progressing through S phase, and in accumulation of large amounts of dsRNA after renewal of progression through the S phase.

Glucocorticoid receptors and inhibition of neonatal mouse dermal fibroblast growth in primary culture

Primary cultures of dermal fibroblasts from neonatal mice were used to investigate some of the anti-inflammatory effects of glucocorticoids in vitro as influenced by the genetic background of two different strains of mice (A/J and C47 Bl/6J). Fibroblasts were cultured in the absence or presence of various glucocorticoids for 2-7 days. After 4-7 days in the presence of steroid, DNA synthesis was reduced by 50-85% while protein synthesis was inhibited by 50-60%. Corticosterone produced a dose-dependent inhibition of DNA synthesis in these cells with a 50% reduction occurring at 10 nM. Specific, high affinity, low capacity binding proteins for [3H]dexamethasone or [3H]triamcinolone acetonide were identified in the cytoplasm of neonatal dermal fibroblasts which had an apparent Kd of 9 nM and approximately 5,200-6,400 binding sites/cell. Sedimentation analysis of the [3H]triamcinolone acetonide-receptor complexes on low salt glycerol gradients exhibited binding in the 7 to 8 S region of the gradients. These studies demonstrate that inhibition of growth of primary cultures of mouse neonatal dermal fibroblasts by glucocorticoids is probably mediated by a receptor-mediated pathway, and that this primary culture system might be useful in delineating other anti-inflammatory effects of glucocorticoids in vitro.

Induction of alkaline phosphatase activity in HeLa cells by sodium butyrate

The induction of HeLa cell alkaline phosphatase activity by sodium butyrate could be inhibited by the coadministration of caffeine or theophylline. The inhibitions were dose dependent, and at any given concentration the potency was theophylline greater than caffeine. Although the induction by sodium butyrate was more sensitive to the inhibition by the xanthines than was that produced by 5-iodo-2'-deoxyuridine, the magnitudes of the increases in cyclic AMP concentrations after treatment with the xanthines were similar in the inhibition of both types of induction. The induction of alkaline phosphatase activity by sodium butyrate also produced a shift in the thermostability pattern of the enzyme, with a proportionately greater increase in the heat-labile, rather than heat-stable, form of the activity.

A rationale for the loss of growth control during experimental bladder carcinogenesis

A rationale is presented which provides an explanation for the loss of growth control which is associated with the early phase of experimentally-induced bladder cancer. Two early events which occur in the urothelium following exposure to carcinogen, the focal loss of alkaline phosphatase activity and the initiation of cell proliferation, are both proposed to be the result of a defect in the interaction between glucocorticoid hormone and urothelium. The possible causes for this defect are discussed in terms of a defect in, or an interference with, the glucocorticoid-receptor mechanism.

The inhibition by xanthine phosphodiesterase inhibitors of the induction of alkaline phosphatase activity in HeLa cells: relationship of enzyme activity to cyclic AMP concentrations

The three xanthine derivatives, caffeine, theophylline and 3-isobutyl-1-methyl-xanthine (IBMX) produced dose-dependent increases in cyclic AMP concentrations in HeLa cells after long term treatment. Only IBMX produced increases over the first 60 minutes, with a peak of approximately 5-fold control values five to 10 minutes after the addition of the drug. About four hours after the addition of either 0.67 or 1.0 mM IBMX there was a second peak in the concentration of cyclic AMP which was at least as large and usually larger than the peak observed at five to ten minutes. Neither caffeine nor theophylline increased cyclic AMP concentrations above control values until one hour after addition of the compounds, and there was no indication of a peak in the concentration at four hours. Between 24 and 72 hours, all three compounds produced elevations in cyclic AMP levels that were steadily maintained. At any given concentration, the order of potency was IBMX greater than theophylline greater than caffeine. If the xanthine derivatives were removed from the medium after 24 hours of treatment, the cyclic AMP concentrations fell to control levels within one hour. Treatment with 5-iodo-2'-deoxyuridine (IdUrd) or hydrocortisone alone did not change the levels of cyclic AMP, nor did the presence of these inducers of alkaline phosphatase activity alter the effects of the xanthine derivations on cyclic AMP concentrations. The data showed a significant correlation between the magnitude of the increase in cycli AMP concentrations over the period from 24 to 72 hours and the degree of inhibition by the xanthine derivatives of the induction of alkaline phosphatase activity.

Involvement of glucocorticoids in the development of the secondary palate

Genetic differences between various inbred strains of mice in the levels of glucocorticoid receptors embryonic in maxillary mesenchyme cells appear to be reflected in the magnitude of the responses to steroids in these cells. High levels of glucocorticoids cause significant growth inhibition in maxillary mesenchyme cells with subsequent alterations in the production of extracellular matrix components. The presence of higher levels of cytoplasmic glucocorticoid receptor proteins may be one factor which could predispose those strains such as A/J to a greater inhibition of craniofacial growth in vivo by glucocorticoids and therefore increase the frequency of cleft palate production. Furthermore, women with infertility treated with glucocorticoids to support pregnancy give birth to infants with a marked decrease in birth weight [98]. Pharmacologic doses of glucocorticoids can also cause a dramatic reduction in the growth of a number of fetal tissues in mice and humans. In fact, there is evidence that glucocorticoids may be a causative factor in the production of cleft palate in primates [52]. The nature of the molecular elements which determine the biochemical and physiologic responses to glucocorticoids in the palate still remains largely unknown. Although in the mouse there is some evidence to suggest that the major histocompatibility locus (H-2) might be involved, the level(s) at which this control is exerted is unknown. It is possible that this locus may regulate in some manner the level of glucocorticoid receptors and the response to glucocorticoids in the secondary palate. Moreover, there is evidence to suggest that other genes distinct from, but closely linked to the H-2 locus may be important in determining both the strain-dependent differences in susceptibility to glucocorticoid-induced cleft palate and the intracellular levels of cyclic AMP in the secondary palate. It is also apparent that glucocorticoids in conjunction with other hormones or growth factors such as epidermal growth factor and agents which regulate cyclic nucleotide metabolism are essential for the normal development of the secondary palate. Excesses or deficiencies in either the level of these growth regulators and/or in their receptors in specific fetal tissues at defined periods in development are likely to lead to certain fetal malformations. Definition and integration of the genetic, biochemical, and endocrine factors which are involved in the control of cellular growth as influenced by alterations in the composition of cell surface and extracellular matrix components should provide some insights into the events associated with normal palatogenesis.

Familial hyperlysinemia: enzyme studies, diagnostic methods, comments on terminology

Enzyme assays of skin fibroblasts from five children with familial hyperlysinemia from unrelated families are added to the previous report of three children from two unrelated families. In all instances there was a deficiency in lysine-ketoglutarate reductase, saccharopine dehydrogenase, and saccharopine oxidoreductase activities. To complete the studies on the enzymes associated with familial hyperlysinemia, saccharopine oxidoreductase was partially purified from human liver and characterized. The activity did not separate from that of lysine-ketoglutarate reductase or saccharopine dehydrogenase. A simple screening test for familial hyperlysinemia is described based on the evolution of 14CO2 from lysine-14C by skin fibroblasts. The test differentiated, without overlap, seven patients with familial hyperlysinemia from control subjects. The relation of the two genetic entities involving lysine degradation, familial hyperlysinemia and saccharopinuria, is discussed. It is suggested that familial hyperlysinemia, type I, be applied to patients with major defects in lysine-ketoglutarate reductase and saccharopine dehydrogenase, and that familial hyperlysinemia, type II, to be used to designate patients in whom significant amounts of lysine-ketoglutarate reductase are retained. The nomenclature would be consistent with that of an analogous disease, orotic aciduria.

Alteration of human breast tumor cell membrane functions by chromosome-mediated gene transfer

BOT-2 cells (human breast tumor origin) have an impaired ability to utilize exogenous thymidine. Previous studies revealed this deficiency to be the permeation event rather than phosphorylation, since the cells have active thymidine kinase. Chromosome-mediated gene transfer was used to transfer genetic information in the form of metaphase chromosomes, from HeLa-65 cells to the BOT-2 cells, correcting the permease deficiency. Poly-L-ornithine or lipochromes were used for facilitation of chromosome uptake. After selection on HAT medium, transferant clones were isolated at a frequency of 4 x 10(-5) and 1 x 10(-5), respectively. Transferants MGP-1 and MGL-1 are stable after 18 months and have been characterized on the bases of purine and pyrimidine nucleoside uptake, relative thymidine kinase activities, alkaline phosphatase activities, and hydrocortisone-induced alkaline phosphatase activity. MGP-1 demonstrates positive thymidine uptake and incorporates radiolabeled thymidine into DNA. MGL-1 remains thymidine transport-deficient and surveys on HAT by increasing endogenous dihydrofolate reductase activity. Alkaline phosphatase activity in MGL-1 is similar to HeLa-65, 2% of that in BOT-2, and in addition, is inducible 25-30-fold by 3 micro M hydrocortisone. We have separated, genetically, a thymidine permease function from phosphorylation in cells of human origin and have transferred genetic information for the regulation of alkaline phosphatase.

Regulation of alkaline phosphatase expression in human choriocarcinoma cell lines

The coincident expression of two structurally distinct isoenzymes of human alkaline phosphatase was demonstrated in two independently derived gestational choriocarcinoma cell lines. These proteins were shown to have enzymatic, antigenic, and physical-chemical properties resembling those of isoenzymes from term placenta and adult liver. The regulation of these isoenzymes has been studied during the exposure of both cell lines to 5-bromodeoxyuridine and dibutyryl cyclic AMP. The responses of the alkaline phosphatase isoenzymes to these agents have also been compared with the response of another protein phenotypic to placenta, the alpha subunit of chorionic gonadotropin. The results show that (i) the separate structural genes coding for placental and liver alkaline phosphatases are regulated in a noncoordinate fashion; (ii) both alkaline phosphatase genes respond independently of the alpha subunit; and (iii) the induction of the placental type isoenzyme occurs via at least two independent pathways.

Inhibition of growth in vitro by glucocorticoids in mouse embryonic facial mesenchyme cells

The growth of primary embryonic facial mesenchyme cells established from cleft palate sensitive A/J and resistant C57BL/6J (C57) mice is inhibited by glucocorticoid treatment. A reduction in cell number in both A/J and C57 culture is accompanied by a significant decrease in [3H] thymidine incorporation into both acid soluble and insoluble material. No significant changes in total cellular protein or [14C] leucine incorporation were observed in either cell type. A greater reduction in [3H] thymidine incorporation occurs in cells undergoing exponential growth following steroid exposure than in cells approaching stationary growth. In both A/J and C57 cultures the reduction in cell number exhibits a dose-dependent response to dexamethasone; is specific for glucocorticoids; and is dependent upon the concentration of serum in which the cells are maintained. A/J cells show a greater sensitivity to the inhibitory effect of dexamethasone on cell number and thymidine incorporation than comparably treated C57 cells. Specific, high affinity, saturable cytoplasmic receptors for [3H] dexamethasone are present in the maxillary cytosols from which the primary cultures were established. These receptors exhibit binding specificity for glucocorticoids, and have properties which are similar to glucocorticoid receptors identified in other systems. In both cell types, a correlation exists between the degree of growth inhibition or reduction of [3H] thymidine incorporation and the level of glucocorticoid receptors. These results provide evidence for a receptor-mediated set of responses to glucocorticoids in these cells.

The effects of glucocorticoids on cultured human endothelial cells

The effects of hydrocortisone, dexamethasone and prednisone on the morphology, replication, DNA synthesis, cell protein content and protein synthesis of cultured, human endothelial cells were evaluated. After culturing the cells with these glucocorticoids for 24-48 h, the cells covered a greater portion of the culture surface area. The mean surface area of the individual endothelial cell treated with glucocorticoids was 1.53 times greater than that of the untreated control endothelial cell. When compared with controls, the endothelial cover provided by the cells treated with glucocorticoids was more extensive and in many instances covered the entire culture surface. The change in morphology was associated with an increase in protein synthesis and protein content of the cells without an increase in DNA synthesis or cellular replication. Dexamethasone was approximately 10-fold more effective than hydrocortisone, while prednisone was the least effective. Aldosterone, DOCA, testosterone, progesterone, oestradiol and oestriol were ineffective. These studies indicate that glucocorticoids can alter the morphology and biochemistry of cultured endothelial cells and may have implications for the effects of steroids in the treatment of thrombocytopenic states and vascular disorders in man.

Rapid cell surface-related stimulation of alkaline phosphatase in HeLa cells by dimethyl DL-2,3-distearoylotypropyl-2'-hydroxyethylammonium acetate (Rosenthal's inhibitor)

Cultures of HeLa cells, strains S3G (HeLa65) and S3K (HeLa71) were grown in plastic dishes until firmly attached and were then treated with sonic dispersions of Rosenthal's phospholipase inhibitor. A rapid increase in alkaline phosphatase activity occurred following this treatment in the S3G strain (low inducible alkaline phosphatase) but not in the S3K strain (high constitutive alkaline phosphatase). The stimulatory effect was dependent on the presence of bovine serum in the medium. No stimulation of alkaline phosphatase was observed in a variety of soluble preparations of this enzyme.

Effects of prednisolone metasulfabenzoate on the induction of DNase II in comparison to alkaline phosphatase and acid phosphatase activities in cultures of HeLa S3 cells

Cultures of HeLa S3 cells were treated with prednisolone metasulfobenzoate (Na), a derivative of prednisolone which is readily soluble in water. The steroid induced an increase in DNase II, a lysosomal enzyme which was not used previously in enzyme induction by steroids. Alkaline phosphatase, a known inducible enzyme by other steroids and acid phosphatase, a known uninducible enzyme by other steroids, were included for comparative reasons.

Cortisol modification of HeLa 65 alkaline phosphatase. Decreased phosphate content of the induced enzyme

Alkaline phosphatase activity of HeLa cells is increased 5-20-fold during growth in medium with cortisol. The increase in enzyme activity is due to an enhanced catalytic efficiency rather than an increase in alkaline phosphatase protein in induced cells. In the present study the chemical composition of control and induced forms of alkaline phosphatase were investigated to determine the enzyme modification that may be responsible for the increased catalytic activity. HeLa alkaline phosphatase is a phosphoprotein and the induced form of the enzyme has approximately one-half of the phosphate residues associated with control enzyme. The decrease in phosphate residues of the enzyme apparently alters its catalytic activity. Other chemical components of purified alkaline phosphatase from control and induced cells are similar; these include sialic acid, hexosamine and sulfhydryl residues.

Regulation of growth and morphological modulation of HeLa65 cells in monolayer culture by dibutyryl cyclic AMP, butyrate and their analogs

N6-O2'-Dibutyryl adenosine-3',5' monophosphate (DBcAMP) markedly altered the morphology of HeLa cells by increasing average cell size with an increase in total cell protein and RNA. Such effects were not caused by adenosine 3',5' monophosphate (cAMP) or related nucleosides and nucleotides. Butyrate, an enzyme catalyzed hydrolysis product of DBcAMP, induced a jagged spindle shape in HeLa cells within 8 hours and then caused them to enlarge and resemble those grown with DBcAMP. These effects were specific for butyrate (C4) and pentanoate (C5) and were not observed with isomers, substituted analogs, or other fatty acid derivatives. These morphological effects were prevented by blocking protein synthesis or by altering the cytoskeleton with Colcemide or cytochalasin B.

Isolation and characterization of alkaline phosphatase-constitutive variants from Chinese hamster ovary cells (CHO-k1)

Pure clones with high alkaline phosphatase (ALP) activity were isolated from Chinese hamster ovary (CHO-K1) cells which showed no detectable ALP activity. ALP-positive cells appeared at the frequency of 10(-4) in the N-methyl-N'-nitrosoguanidine-treated cell population. With respect for cellular morphology, plating efficiency and several other enzymatic activities, no distinct difference was found between the original CHO-K1 cells and its ALP-positive variants, although some alterations in karyotype were found. Levels of ALP activity in these clones was stably maintained during serial cultivation. Some of the enzymological properties of ALP in the isolated clones were similar to those in bone or kidney.