Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: UMLS:C0023418 (leukemia)
93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nicotinamide, a specific inhibitor of poly(ADP-ribose) synthetase, was found to be a moderate inducer of hemoglobin synthesis in Friend erythroid leukemia cells (FLC). Therefore, the effect of other inducers, s-ch as dimethyl sulfoxide (DMSO), hexamethylene-bisacetamide (HMBA), and butyrate, on poly(ADP-ribose) synthesis was examined. The extent of poly(ADP-ribose) synthesis in nuclei of FLC treated with DMSO or HMBA began to decrease before many phenotypic changes including hemoglobin production and reached 30--50% of the level of nontreated control when the cells enter the stationary phase. FLC variants unresponsive to HMBA or DMSO did not exhibit as low an activity of poly(ADP-ribose) synthesis as their parent cells did by treatment with these inducers. In contrast, butyrate stimulated poly(ADP-ribose) synthesis transiently but distinctly (about 50%) at an early stage of culture (6--24 hr), but suppressed it at a later stage. Neither the cell growth nor degradation of poly(ADP-ribose) is correlated with the effect of inducers. These results suggest that the level of poly(ADP-ribose) synthesis is correlated with the differentiation of FLC.
...
PMID:Erythroid differentiation and poly(ADP-ribose) synthesis in Friend leukemia cells. 15 37

Benzamide (BA) enhances the cytotoxicity of 1,2:5,6-dianhydrogalactitol (DAG) in resistant P388 leukemia cell lines but not in the sensitive parent line. To examine the reason for this difference in response, we carried out an alkaline elution assay using proteinase K to study DNA interstrand cross-linking. At early time points, equal concentrations of DAG produced the same level of interstrand cross-linking (ICL) in the resistant and sensitive P388 leukemic cells, although marked differences were observed in their cytotoxicity toward the two cell lines. In the sensitive cells, neither the amount of DNA cross-linking nor the cytotoxicity changed during the observation period (38 h) in either the presence or the absence of BA. In contrast, the elution rate of the DNA of DAG-treated resistant cells increased with time and had reached the control levels by 38 h. However, when these cells were postincubated with BA for 38 h, the elution rate of DNA was much faster than that observed for the untreated resistant cells, indicating an accumulation of DNA single-strand breaks (SSB). The SSB accumulation caused by BA was associated with an inhibition of the activity of ligase II enzyme, which was stimulated when resistant cells were treated with DAG alone. The potentiating effect of BA on the resistant cells can thus be related to the inhibiting action of BA on the DNA-rejoining enzyme, ligase II. The lack of sensitization by BA of the DAG-treated parent cell line may be attributable to the absence of DNA-SSB formation, which is necessary for ligase II activation through the stimulation of poly(ADP-ribose) synthesis.
...
PMID:Benzamide potentiation of the cytotoxicity of bifunctional galactitol [correction of galacticol] in resistant P388 leukemia correlates with inhibition of DNA ligase II. 164 2

Meta-iodobenzylguanidine (MIBG) is a guanidine analogue of the neurotransmitter norepinephrine. Radioiodinated [131I]MIBG is clinically used as a tumor-targeted radiopharmaceutical in the diagnosis and treatment of adrenergic tumors. Moreover, non-radiolabelled MIBG exerts several cell-biological effects, tentatively ascribed to interference with cellular mono(ADP-ribosyl) transferases (Smets, L.A., Bout, B. and Wisse, J. (1988) Cancer Chemother. Pharmacol. 21, 9-13; Smets, L.A., Metwally, E.A.G., Knol, E. and Martens, M. (1988) Leukemia Res. 12, 737-743). In the present study it was investigated whether MIBG could serve as an acceptor for the ribosyl transferase activity of cholera toxin and of erythrocyte membranes. MIBG appeared a substrate for the cholera toxin-catalyzed transfer of the ADP-ribose moiety of NAD to arginine-like residues with the highest affinity for this enzyme reported as yet (Km = 6.5 microM). MIBG was also ADP-ribosylated by the mono(ADP-ribosyl)transferase(s) of turkey erythrocyte membranes. Moreover, the drug appeared a potent affector of the ADP-ribose linkage to membrane proteins by these enzymes. Interference by MIBG was stronger than by related guanyltyramine, the monoamine precursors of MIBG, meta-iodobenzylamine had no effect at all. In contrast, the drug failed to affect endogenous, O-linked poly(ADP-ribose) polymerase, induced in nuclei of S49-leukemia cells by deoxyribonuclease. Since MIBG is the first described drug that specifically interferes with the cellular N-linked mono(ADP-ribosyl) transferase reactions, it may be an important tool to elucidate the physiological role of this posttranscriptional protein modification.
...
PMID:Meta-iodobenzylguanidine (MIBG), a novel high-affinity substrate for cholera toxin that interferes with cellular mono(ADP-ribosylation). 210 58

In order to exert its antitumor effects, the C-nucleoside tiazofurin (2-beta-D-ribofuranosylthiazole-4-carboxamide) is converted to the dinucleotide TAD (thiazole-4-carboxamide adenine dinucleotide), an inhibitor of IMP dehydrogenase (IMPD). With few exceptions, sensitive tumors (such as the P388 leukemia) have been found to accumulate substantially more of this inhibitory dinucleotide than resistant strains (exemplified by the colon 38 carcinoma). Previous studies have attributed this difference to a depressed capacity to synthesize TAD on the part of tumors refractory to tiazofurin. In the present study, a second contributory factor has been identified, viz. an enhanced ability to degrade preformed TAD. This degradation has been traced to a soluble phosphodiesterase present at high levels in tumors naturally resistant to tiazofurin. Using standard techniques, this TAD-phosphodiesterase has been purified 200-fold from the colon 38 carcinoma. The activity so purified readily hydrolyzed TAD and ADP-ribose, but exhibited a comparatively weak activity toward NAD and thymidine-5'-monophosphate-nitrophenyl ester. ADP-Ribose was also an excellent inhibitor of the hydrolysis of TAD. It is concluded, on the basis of these results, that TAD-phosphodiesterase plays an important role in the expression of the oncolytic activity of tiazofurin. The suggestion is also made that ADP-ribose may be the natural substrate for this enzyme.
...
PMID:Studies on the mechanism of action of tiazofurin (2-beta-D-ribofuranosylthiazole-4-carboxamide). VI. Biochemical and pharmacological studies on the degradation of thiazole-4-carboxamide adenine dinucleotide (TAD). 287 71

Variants of mouse leukaemia L1210 cells have been isolated in which cytotoxicity to dimethyl sulphate is not fully potentiated by ADP-ribosyl transferase inhibitor 3-aminobenzamide, as occurs in normal L1210 cells. These variants were selected after mutagenesis by growing the cells in dimethyl sulphate and 3-aminobenzamide. The characterisation of one of these variants is described. Variant 3 cells repair low doses of DNA damage in the presence of ADP-ribosyl transferase inhibitors. The Vmax of the ADP-ribosyl transferase enzyme in these cells is only increased 35% compared to normal wild-type L1210 cells. The basal DNA ligase I activity is increased 66% above wild-type whereas DNA ligase II activity appears to be unchanged. The most striking observation, however, is that the DNA ligase II activity is not increased after dimethyl sulphate treatment as occurs in wild-type L1210 cells. It seems that by increasing DNA ligase I levels these cells can survive DNA damage in the presence of 3-aminobenzamide. This variant (mutant) provides genetic evidence for our previously published hypothesis that (ADP-ribose)n biosynthesis is required for efficient DNA repair after DNA damage by monofunctional alkylating agents, because ADP-ribosyl transferase activity regulates DNA ligase activity. This variant is the first mammalian cell reported in which DNA ligase activity is altered, as far as we are aware. In yeast, a DNA ligase mutant has a cell division cycle (cdc) phenotype. Presumably, DNA ligase is essential for DNA synthesis, repair and recombination. The present variant provides further evidence that in mammalian cells, DNA ligase II activity is related to ADP-ribosyl transferase activity.
...
PMID:A mammalian cell variant in which 3-aminobenzamide does not potentiate the cytotoxicity of dimethyl sulphate. 301 97

Inhibitors of poly(ADP-ribose) polymerase show a synergistic potentiation of cytotoxicity with certain DNA-damaging agents. Non-toxic concentrations of 5-methylnicotinamide dramatically potentiate the cytotoxicity of N-methyl-N-nitrosourea as tested by the cloning ability of mouse leukaemia (L1210) cells. A dose-enhancement factor of about 10 is observed. This potentiation is dependent on the concentration of 5-methylnicotinamide. The methylxanthines theobromine, theophylline and caffeine also increase the cytotoxicity of methylnitrosourea. Thymidine, in the presence of sufficient deoxycytidine to overcome the perturbation of deoxynucleotide metabolism, also potentiates the cytotoxicity of methylnitrosourea. Nicotinate, which is not an inhibitor of poly-(ADP-ribose) polymerase, has no effect on methylnitrosourea toxicity. A very small, but consistent, enhancement of the toxicity of gamma-radiation by the same inhibitors has been observed. We suggest that this potentiation of cytotoxicity is mediated by inhibition of (ADP-ribose)n biosynthesis; and that the biosynthesis is stimulated by DNA damage. We therefore propose that (ADP-ribose)n takes part in cellular repair mechanisms, either by modifying chromatin structure or by a specific participation in DNA repair.
...
PMID:The enhancement of cytotoxicity of N-methyl-N-nitrosourea and of gamma-radiation by inhibitors of poly(ADP-ribose) polymerase. 624 84

DNA damage and repair was assayed by the loss and restoration of DNA supercoiling in nucleoids. This technique was used to assess the effects of inhibition of (ADP-ribose)n biosynthesis by 3-aminobenzamide on the capacity to repair DNA of mouse leukaemia L1210 cells following damage by gamma-irradiation and by the monofunctional alkylating agent, dimethyl sulphate. 3-Aminobenzamide partially inhibits restoration of supercoiling following gamma-irradiation and dimethyl sulphate treatment, but inhibits neither the enzymic incision events leading to breaks in the DNA nor the repair synthesis. This inhibition of repair can be observed at very low doses of damaging agents. These observations confirm and extend the evidence that (ADP-ribose)n biosynthesis is required for efficient cellular recovery from DNA damage. In particular, the nucleoid technique permits the demonstration that 3-aminobenzamide inhibits DNA repair after gamma-radiation; it is not possible to draw this unequivocal conclusion with the data from alkaline sucrose gradients because this technique is too insensitive. 1-beta-D-Arabinofuranosylcytosine, which inhibits semiconservative DNA replication, also retards repair, and this effect can be reversed by the addition of deoxycytidine. The inhibitors of DNA excision repair, arabinosylcytosine, hydroxyurea or 3-aminobenzoamide increase the steady-state number of DNA breaks. Thus, they can be used to enhance even further the sensitivity of the nucleoid assay of repair.
...
PMID:The effect of inhibition of (ADP-ribose)n biosynthesis on DNA repair assayed by the nucleoid technique. 732 71

The function of nicotinamide adenine dinucleotide (NAD) and adenosine diphosphate (ADP) ribosylation reactions in the mechanism of apoptotic cell death is controversial, although one theory postulates an essential role for NAD depletion by poly-ADP-ribose polymerase. The present study examined the role of intracellular NAD in tumor necrosis factor (TNF) and ultraviolet (UV) light-induced activation of the 24-kD apoptotic protease (AP24) leading to internucleosomal DNA fragmentation and death. Our results demonstrate that nutritional depletion of NAD to undetectable levels in two leukemia lines (U937 and HL-60) renders them completely resistant to apoptosis. This was attributed to a block in the activation of AP24 and subsequent DNA cleavage. Normal cells show an elevation of ADP-ribosyl transferase (ADPRT) in both the cytosol and nucleus after exposure to TNF, but before DNA fragmentation. ADPRT activity as well as cell death was suppressed by an inhibitor specific for mono-ADPRT. Nuclei from NAD-depleted cells were still sensitive to DNA fragmentation induced by exogenous AP24, indicating a selective function for NAD upstream of AP24 activation in the apoptotic pathway. We confirmed a requirement for intracellular NAD, activation of ADPRT, and subsequent NAD depletion during apoptosis in KG1a, YAC-1, and BW1547 leukemia cell lines. However, this mechanism is not universal, since BJAB and Jurkat leukemia cells underwent apoptosis normally, even in the absence of detectable intracellular NAD. We conclude that TNF or UV light-induced apoptotic cell death is not due to NAD depletion in some leukemia cell lines. Rather, NAD-dependent reactions which may involve mono-ADPRT, function in signal transduction leading to activation of AP24, with subsequent DNA fragmentation and cell death.
...
PMID:Biochemical pathways of apoptosis: nicotinamide adenine dinucleotide-deficient cells are resistant to tumor necrosis factor or ultraviolet light activation of the 24-kD apoptotic protease and DNA fragmentation. 862 59

Human CD38 is a 45-kDa transmembrane protein that acts as a bifunctional ectoenzyme, catalyzing the synthesis of cyclic ADP-ribose (cADPR) from NAD+ and the hydrolysis of cADPR to ADP-ribose. All-trans-retinoic acid (RA) is a potent and specific inducer of CD38 in myeloid cells. In this report, we demonstrate that RA-induced CD38 protein from human myeloid (HL-60) leukemia cells coimmunoprecipitates with another protein of molecular mass approximately190 kDa (p190). The p190 protein is localized exclusively in the membranes and is a consequence of post-translational cross-linking of CD38 protein. This conclusion was based on the observations that purified CD38 effectively competes with p190, its accumulation is preceded by the accumulation of CD38, it immunoreacted with three different monospecific anti-CD38 antibodies on immunoblots, and its peptide map revealed several peptides in common with CD38. Furthermore, CD38 could serve as a suitable substrate for transglutaminase (TGase)-catalyzed cross-linking reactions in vitro, and the accumulation of p190 in RA-treated HL-60 cells is effectively blocked by the presence of TGase-specific inhibitor. The purified p190 showed at least three times more cyclase activity than CD38. Conversely, p190 was at least 2.5-fold less active than CD38 in hydrolyzing cADPR to ADPR. These results suggest that post-translational modification of CD38 may represent an important mechanism for regulating the two catalytic activities of this bifunctional enzyme.
...
PMID:Post-translational modification of CD38 protein into a high molecular weight form alters its catalytic properties. 866 50

The molecular mechanisms for sensitivity and resistance of tumor cells towards chemotherapy are only partially understood. In chemosensitive leukemias and solid tumors, anticancer drugs have been shown to induce apoptosis. We previously identified activation of the CD95 (APO-1/Fas) receptor/CD95 ligand (CD95/CD95-L) system as a key mechanism for drug-induced apoptosis. Here, we show that therapeutic concentrations of doxorubicin, methotrexate and cytarabine also induce apoptosis via activation of the CD95 system in primary leukemia cells in vivo. CD95-resistant and doxorubicin-resistant leukemia and neuroblastoma cells display cross-resistance for induction of cell death. Down-regulation of CD95 expression was found in drug-resistant and CD95-resistant cell lines. Furthermore, up-regulation of CD95-L, previously shown to mediate drug-induced apoptosis in a variety of tumor cells, was completely blocked in doxorubicin-resistant cells. The prototype caspase (ICE/Ced-3 protease) substrate, poly(ADP-ribose)polymerase (PARP), was cleaved in sensitive, but not in resistant tumor cells following CD95 triggering or drug treatment. Since failure to activate CD95-L was not due to decreased drug uptake or increased drug efflux, non-multi-drug resistance (non-MDR) mechanisms are involved in this type of resistance. These findings suggested that an intact CD95 system plays a key role in determining sensitivity or resistance towards anticancer therapy.
Leukemia 1997 Nov
PMID:Deficient activation of the CD95 (APO-1/Fas) system in drug-resistant cells. 936 15


1 2 3 4 5 6 7 8 9 10 Next >>

---