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At least 415 records · Page 23Linked to original sources
PubMed2005

Position of STAT-1 alpha in cycloheximide-dependent apoptosis triggered by TNF-alpha in human colorectal COLO 205 cancer cell line; role of polyphenolic compounds.

"Immune escape" is a crucial instrument used by carcinoma cells to overcome numerous strategies of immune system to delete transformed cells. Cellular factors that make cancer cells immune to defence mechanisms are incompletely understood while some remain ambiguous. Up to date evidence points to some proteins and/or signaling molecules that might be a basis for unusual behavior of cancer cells. In particular STAT kinases are currently in the main focus of attention since they were both shown to accelerate and/or to inhibit apoptosis. In our studies we observed that human colorectal COLO 205 cancer cells were resistant to TNF-alpha- or cycloheximide-induced cytotoxicity. However, when TNF-alpha (10 ng/ml) has been given along with cycloheximide (5 micro g/ml, CHX) COLO 205 cells died extensively from apoptosis. Apparently, cycloheximide sensitized cells to TNF-alpha-induced programmed cell death. To investigate the role of STAT-1 alpha in CHX-mediated TNF-alpha-induced COLO 205 cell death certain polyphenolic compounds were studied if they modulate STAT-1 alpha phosphorylation status and STAT-1 alpha-protein interaction at the level of TNF-alpha signalosome in the 6(th), 12(th), and 24(th) hour of experiment. Neither of phenolic compound, namely PI-3K inhibitor (LY294002, 20 microM) nor MEK inhibitor (PD98059, 50 microM), nor flavonol quercetin or kaempferol (10, 100 microM) in contrast to apigenin (20 microM) influenced COLO 205 cell viability during individual or combined treatment with TNF-alpha and CHX. We conclude, that some antiapoptotic proteins were involved but not STAT-1 alpha kinase to resist TNF-alpha-dependent cell death promoting activity. Summing up, except apigenin, the above-mentioned polyphenolic compounds were unable to modulate survival signal in COLO 205 cells initially believed to be suppressed by STAT-1 alpha.

Apigenin↗
PubMed2005

[Experimental study on induction of the normal human melanocytes apoptosis in vitro by cycloheximide and TNF-alpha].

OBJECTIVE: To investigate the effects of cycloheximide and TNF-alpha on melanocyte (MC). METHODS: Melanocyte apoptosis was studied with MTT, transmitting electron microscopy and fluorescence labeling of alive cells. RESULTS: We added TNF-alpha and cycloheximide in melanocytes, and the typical apoptosis appeared 24 hours later, with chromatin condensation, nuclear pyknosis and apoptotic bodies formation. The results of cytometry showed the typical apoptotic peak. CONCLUSION: TNF-alpha and cycloheximide together could inhibit MC proliferation and induce MC apoptosis.

Adolescent↗
PubMed1992

Reduction of levels of nuclear-associated protein in heated cells by cycloheximide, D2O, and thermotolerance.

Hyperthermia increases levels of nuclear-associated proteins in a manner that correlates with cell killing. If the increase in nuclear-associated proteins represents a lethal lesion then treatments that protect against killing by heat should reduce and/or facilitate the recovery of levels of the proteins in heated cells. This hypothesis was tested using three heat protection treatments: cycloheximide, D2O, and thermotolerance. All three treatments reduced levels of the proteins measured immediately following hyperthermia at 43.0 or 45.5 degrees C, with the greatest reduction occurring at 43.0 degrees C. In addition to reducing the proteins, thermotolerance facilitated the recovery of the proteins to control levels following hyperthermia. Thus thermotolerance may protect cells by both reducing the initial heat damage and facilitating recovery from that damage. Cycloheximide and D2O did not facilitate recovery of nuclear-associated proteins, suggesting that their protection against cytotoxicity related to the proteins resulted solely from their reduction of increases in levels of the proteins. All three treatments have been shown to stabilize cellular proteins against thermal denaturation. The results of this study suggest that the increase in nuclear-associated proteins may result from thermally denatured proteins adhering to the nucleus and that it is the ability of cycloheximide, D2O, and thermotolerance to thermostabilize proteins that reduces the increase in levels of the proteins within heated cells.

Adaptation, Physiological↗
PubMed1990

[The effect of oligomycin and cycloheximide on the ultrastructure of the segregation apparatus and on protein synthesis in the erythrocytes of the common frog].

The incubation of frog erythrocytes in the Ringer solution with novocaine (4.6 x 10(-3) M) during 24 hours at 10 degrees C provoked vacuole formation (segregation zones). Changes of the novocaine solution for a fresh Ringer solution and the following 48 hour incubation was accompanied by a decrease in the number of vacuoles both electron-translucent and containing membranous material. Simultaneously, the number of vacuoles with amorphous material only and with amorphous and membranous substances was seen to increase. Under the action of cycloheximide (1.10(-2) M) or oligomycin (2.5 x 10(-6) M) on erythrocytes with preformed vacuoles for 48 hours the total number of vacuoles and their dimensions decreased, with numerous amorphous inclusions appearing. Vacuoles with amorphous and membranous material increased in size. Similar ultrastructural changes in the segregation zones under the influence of both the inhibitors were observed showing the appearance of thick threads and a decreased share of electron-translucent vacuoles. A specific effect of cycloheximide, compared to that of oligomycin, involved the expansion of smooth endoplasmic reticulum cisternae. Under the influence of novocaine, 3H-leucin incorporation in proteins of frog erythrocytes was intensified. However, this incorporation was considerably inhibited by cycloheximide. Erythrocytes with segregation zones were more inhibitor susceptible than erythrocytes without vacuoles. The inhibitory effect was stronger early after their administration to the incubation medium, compared to the later periods.

Animals↗
PubMed1990

[The effect of translation inhibitor cycloheximide on expression of mammalian genes].

The data concerning the cycloheximide influence on individual mRNA content, transcription rate and chromatin structure in mammalian cells are reviewed. The putative mechanism of cycloheximide effect is explained as being due to the existence of short-living regulatory proteins. It is concluded that cycloheximide is a helpful tool in the study of regulation of gene expression in mammalian cells.

Animals↗
PubMedDate not supplied

[The parthenogenetic activation under the action of cycloheximide of mouse oocytes matured in vivo].

Treatment of mouse oocytes matured in vivo by cycloheximide at a concentration 25 micrograms/ml for 2 h induced female pronucleus formation. In all activated oocytes the formation of the female nucleus was completed 5-6 h after the beginning of cycloheximide treatment. When cycloheximide concentration was decreased down to 5 micrograms/ml, its effect was detected 1 h later as compared with that at a concentration of 25 micrograms/ml.

Animals↗
PubMed1989

Protein synthesis inhibition by cycloheximide does not affect the acute release of tissue-type plasminogen activator.

The acute release of tissue-type plasminogen activator (t-PA) was studied in perfused rat hindlegs. Pretreatment of rats with the protein syNthesis inhibitor cycloheximide (2 mg/kg) at 1, 3 or 5 h prior to perfusion of rat hindlegs did not influence the amount of t-PA released by platelet-activating factor (20 nM) or bradykinin (1 microM). The amount of t-PA activity that could be extracted from hindleg skeletal muscle was not decreased by cycloheximide pretreatment though it was decreased in lung extracts. The in vivo release of t-PA was not affected by cycloheximide pretreatment. The data suggest that the acute release of t-PA from vascular endothelial cells does not require ongoing protein synthesis, but that acutely released t-PA is derived from a stable endothelial storage pool.

Animals↗
PubMed1989

[DNA synthesis in the nuclei of stimulated NIH 3T3 cells in heterodikaryons obtained by the fusion of these cells with resting cells treated with cycloheximide].

Serum-deprived (0.2%) resting NIH 3T3 mouse fibroblasts preincubated with cycloheximide (7.5 micrograms/ml) were fused with stimulated cells taken 10 hours after changing the medium to the one containing 10% serum, and DNA synthesis was investigated in nuclei of heterodikaryons, homodikaryons, and monokaryons, using radioautography with double-labeling technique. Preincubation of resting cells with the inhibitor of protein synthesis cycloheximide for 4, 3, 2, but not for 1 or 0.5 hours abolishes their ability to suppress DNA synthesis in stimulated nuclei in heterodikaryons. Three hours after the removal of cycloheximide from the media, the resting cells acquire once again the inhibitory effect towards the entry of stimulated nuclei into the S-period. The data suggest that the resting cells may produce a labile endogenous inhibitor of cell proliferation, and support the idea on the active metabolic processes occurring in the resting cells.

Animals↗
PubMed1986

Interferon-gamma, mitomycin C, and cycloheximide as regulatory agents of MHC class II-associated invariant chain expression.

The murine and human major histocompatibility complex class II-associated invariant chain genes are expressed in mature B cells and in antigen-presenting cells. Several pre-B cell lines and fibroblasts do not naturally contain invariant chain mRNA. Expression is inducible, however, by interferons and other agents interfering with proliferation. Mitomycin C induces the transcription of the gene in pre-B cells, but not in fibroblasts. Interferon-gamma acts in both types of cells. Cycloheximide inhibits the induction of the invariant chain mRNA by interferon-gamma, suggesting that protein synthesis is required. In fact, cycloheximide itself increases the transcriptional rate at the invariant chain gene, suggesting the existence of a labile repressor or an indirect action through cycloheximide arrest of the cell cycle. Lipopolysaccharide (LPS) activation of B lymphocytes causes a rapid decrease of the invariant chain mRNA level and of the amount of invariant chain protein due to rapid turnover. Also class II alpha and beta mRNA expression decreases after LPS treatment. The decrease of invariant chain protein is accompanied by increased surface expression of alpha and beta. The murine invariant chain gene transfected into human fibroblasts is regulated by the same agents and the same dose of agents as is the endogenous gene. The differentiation marker invariant chain thus seems to be transcribed from a gene that is accessible to regulation even in nonlymphoid cells and the expression of which is linked to states of nonproliferation. The sequence responsible for these responses is contained within the cloned genomic fragment and is conserved between mouse and man.

Actins↗
PubMed1988

Regulation of interleukin 1 production in human monocytes. I. Effects of gamma-interferon and cycloheximide.

The objective of these studies was to investigate mechanisms of regulation of interleukin 1 (IL-1) production by human monocytes. IL-1 production was measured by augmentation of phytohemagglutinin-induced proliferation of murine thymocytes. Adherent human monocytes incubated in medium for one day exhibited a marked decrease in lipopolysaccharide (LPS)-induced IL-1 production over a second day. Cells pre-incubated in 100 U/ml gamma interferon (gamma-IFN) for 24 h displayed a partial to complete maintenance of LPS-induced IL-1 production. Studies with inhibitors of cyclo-oxygenase or lipoxygenase indicated that prostaglandins or leukotrienes were not responsible for the alterations in IL-1 production observed with cultured cells or for the effects of gamma-IFN. Monocytes were pre-incubated in cycloheximide for 24 h and the drug was washed out. These cells exhibited an enhancement in IL-1 production over a second 24 h culture in the presence of 2 ng/ml LPS. Furthermore, the partial maintenance of LPS-induced IL-1 production seen after cells were pre-incubated in gamma-IFN was markedly increased by the inclusion of 0.25 microgram/ml cycloheximide during the 24 h pre-incubation. These results indicate that IL-1 production may be inhibited by newly-synthesized proteins during maturation in vitro or differentiation of monocytes into macrophages. Pre-incubation in gamma-IFN and cycloheximide leads to separate but synergistic effects on the maintenance of LPS-induced IL-1 production in cultured monocytes.

Cells, Cultured↗
PubMed1988

[Effect of cycloheximide on transcription in eukaryotic cells].

The effects of the translation inhibitor cycloheximide on transcription in Rauscher virus transformed mouse erythroblasts and in barley rootlets were studied. In transformed erythroblasts, the globin gene transcription appeared to be blocked. Consecutive treatment of cells with sublethal doses of cycloheximide (7 micrograms/ml) and actinomycin D resulted in the induction of synthesis of the protein fraction corresponding to beta-globin chains. An exposure of barley rootlets to cycloheximide caused changes in total RNA synthesis.

Animals↗
PubMed1987

Inhibition of heat shock protein synthesis and thermotolerance by cycloheximide.

Chinese hamster ovary (CHO) cells were exposed to a 43 degrees C, 15-min heat shock to study the relationship between protein synthesis and the development of thermotolerance. The 43 degrees C heat shock triggered the synthesis of three protein families having molecular weights of 110,000, 90,000, and 65,000 (HSP). These proteins were synthesized at 37 and 46 degrees C. This heat shock also induced the development of thermotolerance, which was measured by incubating the cells at 46 degrees C 4 h after the 43 degrees C heat treatment. CHO cells were also exposed to 20 micrograms/ml of cycloheximide for 30 min at 37 degrees C, 15 min at 43 degrees C, and 4 h at 37 degrees C. This treatment inhibited the enhanced synthesis of the Mr 110,000, 90,000, and 65,000 proteins. The cycloheximide was then washed out and the cells were incubated at 46 degrees C. HSP synthesis did not recover during the 46 degrees C incubation. This cycloheximide treatment also partially inhibited the development of thermotolerance. These results suggest that for CHO cells to express thermotolerance when exposed to the supralethal temperature of 46 degrees C protein synthesis is necessary.

Adaptation, Physiological↗
PubMed1987

In vivo effects of dexamethasone and cycloheximide on the phosphorylation of 110-kDa proteins and the protein kinase activities of rat liver nucleoli.

In vivo effects of dexamethasone and cycloheximide on the phosphorylation of nucleolar proteins and the activities of nucleolar protein kinases of rat livers were studied. Phosphorylation of nucleolar proteins was accomplished by incubation of isolated nucleoli with [gamma-32P]ATP at 37 degrees C for 10 min followed by electrophoretic separation and autoradiographic demonstration of phosphorylated proteins. Of several nucleolar phosphoproteins observed in the liver of adrenalectomized rats, the incorporation of 32P into nucleolar 110-kDa proteins was rapidly increased, reaching about 1.8-fold of the adrenalectomized level at 12 h after administration of dexamethasone. In addition, the activities of liver nucleolar protein kinases which were measured using casein or phosvitin as substrates were stimulated similarly by the administration of dexamethasone. It was found by DEAE-Sephadex column chromatography that nucleolar protein kinases were separated into NI and NII, the activities being increased about 35 and 80% by dexamethasone treatment (12 h), respectively, and that the enhancements were completely abolished by 1-h treatment of cycloheximide. The injection of cycloheximide also suppressed the hormone-induced enhancement of 32P incorporation into 110-kDa proteins but did not reduce the amount of the proteins at least until 2 h. Evidence was obtained indicating that the phosphorylation of the nucleolar 110-kDa proteins is accomplished primarily by protein kinase NII. These results suggest that continuous synthesis of protein(s) is necessary for glucocorticoid-induced enhancement of phosphorylation of 110-kDa proteins of liver nucleoli and that the nucleolar protein kinase NII is involved in the glucocorticoid-induced short-lived protein(s).

Adrenal Glands↗
PubMed1987

Effect of cycloheximide or puromycin on induction of thermotolerance by heat in Chinese hamster ovary cells: dose fractionation at 45.5 degrees C1.

While studying the quantitative relationship between hyperthermia-induced heat shock proteins (HSPs) and thermotolerance (TT), we observed that heat induced a family of HSPs, particularly an HSP 70 family, that might be involved in the development of TT. When cells were heated for 10 min at 45.5 degrees C, they became thermotolerant to a second heat exposure at 45.5 degrees C, with a thermotolerance ratio of 5-6 at 10(-3) isosurvival at 12 h after heating. In parallel, during the 12-h interval, heat shock resulted in a 2-fold relative increase in the synthesis of three major HSP families (Mr = 110,000, 87,000, and 70,000). Rate of synthesis was expressed relative to total protein synthesis, as studied with one-dimensional polyacrylamide gels analyzed by counting radioactivity in selected protein bands. The increase of unique HSPs, if studied with two-dimensional gels, would probably be much greater. Furthermore, even though the development of TT was partially suppressed by treatment with cycloheximide (10 micrograms/ml) or puromycin (100 micrograms/ml) at concentrations that inhibited total protein synthesis by 96 or 99%, respectively, a family of HSP 70 was still preferentially synthesized. Nevertheless, when cells were labeled for 3 days, the total level of HSP families did not change either when TT developed after a triggering heat treatment or as the development of TT was partially inhibited by suppressing protein synthesis with cycloheximide or puromycin. Thus, TT could still occur when total levels of HSP families did not change and when synthesis of HSP families was less than in unheated control cells, which may imply that TT is unrelated to HSPs. However, the finding that the amount of TT increased with increased synthesis of both total protein and HSP families, as studied with different concentrations of cycloheximide or puromycin, suggests that heat-inducible proteins, in particular the observed preferential synthesis of the HSP 70 family, may be necessary for the development of TT.

Animals↗
PubMed1986

Effects of alpha-amanitin and cycloheximide on 1,25-dihydroxyvitamin D3-dependent calbindin-D28K and its mRNA in vitamin D3-replete chick intestine.

We have examined the effects of the transcriptional inhibitor alpha-amanitin and the translational inhibitor cycloheximide on levels of calbindin-D28K (28-kDa calcium binding protein, CaBP) and CaBP-mRNA in the vitamin D-replete chick intestine. Chicks were raised on one of four diets: "normal" (1% calcium, 0.6% phosphorus); high calcium (3.3% calcium, 0.5% phosphorus); low calcium (0.3% calcium, 0.6% phosphorus); or low phosphorus (1% calcium, 0.09% phosphorus). Chicks were then treated either with alpha-amanitin (20 micrograms/chick) or cycloheximide (600 micrograms/chick) 2 h prior to a dose of 6.5 nmol of 1,25-dihydroxyvitamin D3. Duodenal mucosa was collected from 0 to 120 min afterward and assayed for CaBP-mRNA by dot blot hybridization and for CaBP using an enzyme-linked immunosorbent assay. In the absence of inhibitor, CaBP levels were depressed by high calcium and elevated by low calcium or low phosphorus, as expected. These changes occurred, however, without a change in CaBP-mRNA levels. alpha-Amanitin had no effect on CaBP or on CaBP-mRNA levels in chicks raised on any of the diets. Cycloheximide inhibited CaBP levels, and surprisingly also inhibited CaBP-mRNA levels in all four dietary groups. These results indicate that continual protein synthesis is necessary for the expression of CaBP-mRNA, suggesting the existence of a rapidly turned over protein that may be required for stabilization or for processing of the chick intestinal CaBP messenger RNA.

Amanitins↗
PubMed1985

[Blocking effect of cycloheximide on decreased mitochondrial resistance due to thyroid hormone action].

Administration of cycloheximide (20-25 micrograms/kg bw twice, interval 24 h) to hyperthyroid rats (300 micrograms/T4/100 g bw i. p. 48 h before sacrifice) inhibited the decrease in mitochondrial resistance to Ca2+ characteristic of hyperthyroidism. It was established in particular that calcium capacitance of the mitochondria and the time of the maintenance of transmembrane potential of these organelles under calcium loading were increased in the mitochondria of hyperthyroid animals given cycloheximide as compared with analogous parameters of the organelles of intact hyperthyroid rats. Moreover, the fluorescence intensity of NADPH in the mitochondria of the first group of animals was 37% greater and the rate of oxidation of these nucleotides several times lower than in the organelles of the second group animals. It is assumed that the described effects of cycloheximide on the mitochondria are linked with the inhibitory effect of the antibiotic on endogenous activity of mitochondrial phospholipase A2.

Animals↗
PubMedDate not supplied

[mRNA degradation in membrane-bound and free polyribosomes in rat liver cells after exposure to actinomycin D and cycloheximide].

Actinomycin D caused degradation of mRNA both in membrane-bound and in free polyribosomes from rat liver cells. The rate of mRNA destruction was distinctly higher in free polyribosomes, than in membrane-bound ones. Cycloheximide inhibited the mRNA destruction in both types of polyribosomes. At the same time, the stabilizing effect of cycloheximide on mRNA was less distinct in free polyribosomes. A decrease in specific radioactivity of mRNA from membrane-bound and free polyribosomes was observed after prolonged pretreatment with actinomycin D. The specific radioactivity of mRNA from polyribosomes of both types was not altered after simultaneous administration of actinomycin D and cycloheximide into rats. Occurence of two fractions of mRNA, dissimilar in stability, is possible both in membrane-bound and in free polyribosomes from rat liver cells.

Animals↗
PubMedDate not supplied

[mRNA breakdown in tumor cells in vivo under cycloheximide protein synthesis inhibition].

Amoung of prelabelled mRNA was unaltered in Zajhdel ascites hepatoma of rat cells within 3.5-4 hrs under conditions of treatment with actinomycin D. Due to combined effect of actinomycin D and cycloheximide the content of mRNA in the hepatoma cells was rapidly decreased. Degradation of mRNA occurred in membrane-bound polyribosomes, free polyribosomes and in cytoplasmic mRNP-particles /informosomes/ as a result of the effect of cycloheximide. Simultaneously with these phenomena, distinct increase in activity of acid and alkaline RNAases was observed in cytoplasma of the hepatoma cells; activity of endoRNAase from membrane-bound and free polyribosomes of the hepatoma was also markedly increased. Cycloheximide did not affect the activity of polynucleotide phosphorylase in polyribosomes of the hepatoma cells. Labile proteins, responsible for inhibition of RNAses appeart to participate in regulation of mRNA stability in malignant cells.

Animals↗