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

Growth of human hematopoietic cell lines showed a 100-fold range of sensitivity to inhibition by 2-chloro-2'-deoxyadenosine (CldAdo), with highly sensitive lines in all three groups: T-lymphoblastic, B-lymphoblastic, and non-T, non-B. Formation of nucleotides from [8-3H]CldAdo was investigated in ten lines. In cells exposed to 0.15 microM CldAdo, CldAdo 5'-phosphate (CldAMP) reached 0.7-14 microM and CldAdo 5'-triphosphate (CldATP) reached 0.05-6 microM in 1 h. In most cases these nucleotide concentrations at 1 h were close to the steady-state concentrations, and the latter concentrations were approximately proportional to extracellular CldAdo concentration. On removal of extracellular CldAdo, intracellular CldAMP and CldATP declined rapidly with half times of 0.56-0.9 and 0.64-1.46 h, respectively. There was no correlation between these rates of catabolism and steady-state levels. The different sensitivities of the lines to CldAdo is explained only in part by the different steady-state concentrations of CldATP, and must be more directly related to differential effects on target enzymes. Mice inoculated with L1210 leukemia were treated with 2-bromo-2'-deoxyadenosine (BrdAdo) paired with one of 18 other therapeutic agents. Eight of the drugs paired with BrdAdo gave therapeutic responses from the combination greater than the sum of the responses of members of the pair. They included alkylating agents, antimetabolites blocking deoxyribonucleotide synthesis, and DNA polymerase inhibitors. Toxic dosages of CldAdo caused damage chiefly to the hemic-lymphatic systems and the kidneys.
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PMID:Biochemical pharmacology of 2-chlorodeoxyadenosine in malignant human hematopoietic cell lines and therapeutic effects of 2-bromodeoxyadenosine in drug combinations in mice. 256 29

A number of 6-substituted and 2,6-disubstituted pyrrolo[2,3-d]pyrimidine 2'-deoxyribonucleosides were prepared by the direct stereospecific sodium salt glycosylation procedure. Reaction of the sodium salt of 4-chloro-6-methyl-2-(methylthio)pyrrolo[2,3-d]pyrimidine (6a) or 4,6-dichloro-2-(methylthio)pyrrolo[2,3-d]pyrimidine (6b) with 1-chloro-2-deoxy-3,5-di-O-p-toluoyl-alpha-D-erythro-pentofuranose (9) provided the corresponding N7 2'-deoxy-beta-D-ribofuranosyl blocked derivatives (8a and 8c) which, on ammonolysis, gave 4-amino-6-methyl-2-(methylthio)-7-(2-deoxy-beta-D-erythro-pentofuranosyl )pyrrolo[2,3-d]pyrimidine (11a) and 4-amino-6-chloro-2-(methylthio)-7-(2-deoxy-beta-D-erythro-pentofuranosyl )pyrrolo[2,3-d]pyrimidine (11b), respectively. Dethiation of 11a and 11b afforded 6-methyl-2'-deoxytubercidin (10a) and 6-chloro-2'-deoxytubercidin (10b), respectively. Dehalogenation of 10b provided an alternate route to the reported 2'-deoxytubercidin (3a). Application of this glycosylation procedure to 4,6-dichloro and 4,6-dichloro-2-methyl derivatives of pyrrolo[2,3-d]pyrimidine (15a and 15b) gave the corresponding blocked 2'-deoxyribonucleosides (18a and 18b), which on ammonolysis furnished 10b and 4-amino-6-chloro-2-methyl-7-(2-deoxy-beta-D-erythro- pentofuranosyl)pyrrolo[2,3-d]pyrimidine (17), respectively. This stereospecific attachment of the 2-deoxy-beta-D-ribofuranosyl moiety appears to be due to a Walden inversion at the C1 carbon by the anionic heterocyclic nitrogen. Controlled deacylation of 4-chloro-7-(2-deoxy-3,5-di-O-p-toluoyl-beta-D-erythro-pentofuranosyl) pyrrolo[2,3-d]pyrimidine (20a) gave 4-chloro-7-(2-deoxy-beta-D-erythro-pentofuranosyl)pyrrolo[2,3-d] pyrimidine (20b). Dehalogenation of 20b gave the 2'-deoxynebularin analogue 7-(2-deoxy-beta-D-erythro-pentofuranosyl)pyrrolo[2,3-d]pyrimidine (19), and reaction of 20b with thiourea gave 7-(2-deoxy-beta-D-erythro-pentofuranosyl)pyrrolo[2,3-d]pyrimidine-4(3H)- thione (21). All of these compounds were tested in vitro against certain viruses and tumor cells. Only compounds 12a, 20b, and 21 showed significant activity against measles in vitro, and the activity is comparable to that of ribavirin. Although compounds 3a and 12b are slightly more active than ribavirin against HSV-2 in vitro, they are relatively more toxic to Vero cells. Compounds 3a and 20b exhibited moderate cytostatic activity against L1210 and P388 leukemia in vitro but are considerably less active than 2-chloro-2'-deoxyadenosine (1).
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PMID:Synthesis and biological activity of certain 6-substituted and 2,6-disubstituted 2'-deoxytubercidins prepared via the stereospecific sodium salt glycosylation procedure. 299 66

Experimental evidence has indicated that T lymphoblasts are more sensitive to deoxynucleoside toxicity than are B lymphoblasts. These data have led to the use of purine enzyme inhibitors as selective chemotherapeutic drugs in the treatment of T cell malignancies ranging from T cell acute lymphoblastic leukaemia to cutaneous T cell lymphomas. We have compared the toxicities of 2'-deoxyadenosine, 2'-deoxyguanosine, and thymidine for T cell lines derived from patients with T cell acute lymphoblastic leukaemia with those for mature T cell lines derived from patients with cutaneous T cell leukaemia/lymphoma. We have found that both deoxynucleosides are far less toxic to the mature T cell lies than to T lymphoblasts and that the mature cells accumulate much lower amounts of dATP and dGTP when exposed to deoxyadenosine and deoxyguanosine, respectively. Similar studies performed on peripheral blood cells from patients with T cell leukaemias of mature phenotype and on peripheral blood T cells demonstrate similar low amounts of deoxynucleotide accumulation. Measurements of the activities of several purine metabolizing enzymes that participate in deoxynucleoside phosphorylation or degradation do not reveal differences which would explain the toxicity of deoxynucleosides for immature, as compared to mature, T cells. We conclude that deoxynucleoside metabolism in leukaemic T cells varies with their degree of differentiation. These observations may be relevant to the design of chemotherapeutic regimes for T cell malignancies.
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PMID:Differential metabolism of deoxyribonucleosides by leukaemic T cells of immature and mature phenotype. 299 81

Cultured human T-lymphoblastoid cell lines are more sensitive than B-cell lines to 2'-deoxyadenosine in the presence of 2'-deoxycoformycin, a potent inhibitor of adenosine deaminase. This difference is related to the greater efficiency with which T-lymphoblasts accumulate cytotoxic levels of dATP derived from the adenosine deaminase substrate 2'-deoxyadenosine (dAdo). Previous work has shown that differences in dATP accumulation by cultured T- and B-lymphoblastoid cell lines cannot be explained by large differences in the levels of dAdo-phosphorylating or dAdo nucleotide (dAXP)-degrading activities in cytoplasmic extracts of these cells, although it has been proposed that intact B-cell lines may catabolize intracellular dAXP more rapidly than do T-cell lines. To further examine the determinants of dAdo sensitivity in T- and B-lymphoblasts, we have studied dAdo and dAXP metabolism in the human T- and B-cell lines CEM and WI-L2 and in hybrids generated by fusion of these cell lines. The hybrid nature of the fusion products was established by nutritional studies and by analyses of cellular surface antigens, DNA content, and enzymatic activities. We found that WI-L2 X CEM hybrids and another T X B hybrid derived from fusion of the SB human B-cell line with CEM were 30- to 40-fold less sensitive to dAdo and about 10-fold less sensitive to the dAdo analogue 9-beta-D-arabinofuranosyladenine than was CEM, or about as resistant as were their B-cell parental lines. Our studies confirm that CEM avidly accumulates dAXP from dAdo but does not catabolize intracellular dAXP. In contrast, WI-L2, SB, and WI-L2 X CEM and SB X CEM hybrids rapidly degraded intracellular dAXP, which limited their ability to undergo dAXP pool expansion. Expression of dAXP catabolic activity in T X B hybrids behaved as a dominant mechanism, conferring resistance to dAdo- and dAdo-related nucleosides to T X B hybrids. It has been postulated that cell fusion may play a role in the progression of tumors and contribute to diversity among the cells that compose clonal tumors. We have speculated that fusion of a malignant T-lymphoblast with an activated B-cell might be a mechanism for the evolution of drug resistance in acute T-cell leukemia.
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PMID:Determinants of deoxyadenosine toxicity in hybrids between human T- and B- lymphoblasts as a model for the development of drug resistance in T-cell acute lymphoblastic leukemia. 387 67

Incubation of deoxycoformycin-treated L1210 leukemia cells with dipyridamole or nitrobenzylthioinosine, inhibitors of nucleoside transport, enhanced the long-term incorporation of 2'-deoxyadenosine and adenosine into the nucleotide pool and the toxicity of 2'-deoxyadenosine for the cells. In contrast, 2'-deoxyadenosine uptake in deoxycoformycin-treated P388 leukemia cells, which was about 10 times greater than that in L1210 cells, was inhibited by dipyridamole and nitrobenzylthioinosine, and 2'-deoxyadenosine toxicity was not significantly affected by the transport inhibitors. P388 cells also were about 6 times more resistant to 2'-deoxyadenosine than were L1210 cells, in spite of the greater uptake of the nucleoside. We found that purine nucleoside transport in L1210 and P388 cells exhibited similar kinetic properties and sensitivity to dipyridamole and nitrobenzylthioinosine (both influx and efflux) and that the stimulation of 2'-deoxyadenosine uptake by the inhibitors in L1210 cells is not mediated at the level of its transport into the cells but rather reflects an enhanced intracellular net accumulation of deoxyadenosine nucleotides.
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PMID:Effects of nucleoside transport inhibitors on the salvage and toxicity of adenosine and deoxyadenosine in L1210 and P388 mouse leukemia cells. 387 68

Both established cell lines and human leukemic cells in circulating blood which were incubated in vitro with 2'-deoxyadenosine (AdR) plus adenosine deaminase inhibitor, 2'-deoxycoformycin (dCF), showed different metabolic responses depending upon the histologic and immunologic types of leukemia. The leukemic T-cell lines in tissue culture were 200-fold more sensitive than B-cell lines to the toxic effect of deoxyadenosine. The increased sensitivity of T-cell lines to AdR plus dCF was associated with the accumulation of deoxyadenosine triphosphate (dATP) in the cells. In established cell lines, an inverse correlation was observed between ED 50 of AdR plus dCF and the relative increase of dATP levels in the cells after the incubation of the cells with AdR plus dCF. In circulating leukemic cells that had been incubated with AdR and dCF, dATP arose in all groups but the correlation was not found between the sensitivity of AdR and the relative dATP accumulation. The failure to find the correlation in patients's leukemic cells may be attributed to the heterogeneity of the response of the blasts to AdR and dCF.
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PMID:Differential sensitivity of leukemic cells to growth inhibition by deoxyadenosine and deoxycoformycin. 387 63

5'-Deoxy-5'-halogenated adenosines are alternative substrates for 5'-deoxy-5'-methylthioadenosine phosphorylase (MTAPase), an enzyme responsible for the metabolism of 5'-deoxy-5'-methylthioadenosine (MTA), a by-product of polyamine biosynthesis. The relative reactivity of these nucleosides with MTAPase from HL-60 human promyelocytic leukemia cells is MTA greater than 5'-deoxy-5'-fluoroadenosine (5'-FlAdo) greater than 5'-chloro-5'-deoxyadenosine (5'-ClAdo) greter than 5'-bromo-5'-deoxyadenosine (5'-BrAdo) greater than 5'-deoxy-5'-iodoadenosine (5'-IAdo). In MTAPase-containing cells, the adenine released from the 5'-halogenated adenosine was incorporated into adenine nucleotide pools; cleavage by (MTAPase appeared to be the rate-limiting step in this process. 5'-BrAdo and 5'-IAdo were growth inhibitors (EC50 values less than 10 microM) of MTAPase-containing cell lines (HL-60 human promyelocytic leukemia and the L5178Y murine lymphoblastic leukemia) but were much less active (EC50 values greater than 65 microM) against MTAPase-deficient cell lines (the CCRF-CEM human T cell leukemia and the L1210 murine leukemia). The full cytotoxicity of these compounds, therefore, appeared to be related to their phosphorolysis by MTAPase. Indirect evidence suggests that 5-halogenated ribose-1-phosphate derivatives of 5'-BrAdo or 5'-IAdo produced by the MTAPase reaction were the active metabolites of these 5'-halogenated adenosines.
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PMID:5'-Deoxy-5'-methylthioadenosine phosphorylase--III. Role of the enzyme in the metabolism and action of 5'-halogenated adenosine analogs. 391 39

We have previously shown that dexamethasone stimulates production of type-C virus from seemingly normal murine fibroblasts (BALB/3T3) and from transformed (Kirsten sarcoma-leukemia virus) nonproducing cells (BALB/K3T3) induced by 5-iododeoxyuridine. In this report, we further examine the mechanism of this effect by using BALB/K3T3 cells. Several observations suggest that this effect is post-transcriptional. The optimal stimulation by dexamethasone is obtained when dexamethasone is given 24 to 48 h after 5-iododeoxyuridine induction. Although this effect is late, time course experiments suggest that dexamethasone does not act to promote release of preformed virions. The stimulation by dexamethasone is blocked when cells are treated with cordycepin (3'-deoxyadenosine) during the first 24 h of induction, but not when cordycepin is added later. Conversely, interferon, which inhibits virus production, interferes with dexamethasone when it is added late or after removal of the steroid. The results of molecular hybridization experiments show that there is no detectable increase in Kirsten sarcoma-leukemia virus-specific RNA in dexamethasone-treated cells (with or without 5-iododeoxyuridine). The results of the time course studies, and the cordycepin, interferon, and hybridization experiments, suggest that the effect of dexamethasone on type-C virus production in this system is post-transcriptional.
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PMID:Mechanism of stimulation of murine type-C RNA tumor virus production by glucocorticoids: post-transcriptional effects. 437 Jun 54

2-Chlorodeoxyadenosine (CdA), an adenosine-deaminase-resistant purine deoxynucleoside, is markedly toxic toward human T-lymphoblastoid cell lines in vitro and is an effective agent against L1210 leukemia in vivo. The present studies have examined the toxicity, and in some cases, metabolism, of CdA in (1) multiple established human cell lines of varying phenotype, (2) leukemia and lymphoma cells taken directly from patients, (3) normal bone marrow cells, and (4) normal peripheral blood lymphocytes. Nanomolar concentrations of CdA blocked the proliferation of lymphoblastoid cell lines with a high ratio of deoxycytidine kinase to deoxynucleotidase. The drug had virtually no effect on the growth of cell lines derived from solid tissues. The CdA inhibited the spontaneous uptake of tritiated thymidine by many T and non-T, non-B acute lymphoblastic leukemia cell specimens at concentrations less than or equal to 5 nM. The same concentrations did not impair either thymidine uptake or granulocyte-monocyte colony formation by normal bone marrow cells. In common with deoxyadenosine, but unlike several other agents affecting purine and purine metabolism, CdA was lethal to resting normal T lymphocytes and to slowly dividing malignant T cells. In both resting and proliferating lymphocytes, the CdA was phosphorylated by deoxycytidine kinase and entered a rapidly turning over nucleotide pool. Dividing lymphocytes also incorporated abundant CdA into DNA. The selective toxicity of CdA toward both dividing and resting lymphocytes may render the drug useful as an immunosuppressive or antileukemic agent.
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PMID:Specific toxicity of 2-chlorodeoxyadenosine toward resting and proliferating human lymphocytes. 613 5

Leukemic cells incubated in vitro with 2'-deoxyadenosine (dAdo) plus an inhibitor of adenosine deaminase, 2'-deoxy-coformycin (DCF), show different metabolic responses depending on the histologic and immunologic type of the leukemia. Leukemic cells were obtained from 54 patients with acute lymphoblastic leukemia (ALL), 9 with myeloid or nonlymphoblastic leukemia, 3 with chronic lymphocytic leukemia (CLL), and 3 with lymphoma. There was a wide variation in the LD50, the concentration of dAdo that caused 50% inhibition of the incorporation of 3H-thymidine into cells in the presence of 20 microM DCF. T-cell leukemia specimens were much more sensitive to dAdo than were specimens of pre-B-ALL and null-ALL. In leukemic cells that had been incubated with 14C-dAdo plus DCF, a good correlation was observed between the LD50 and the ratio of 14C-deoxyATP to ATP (correlation coefficient for the fit to a hyperbola = 0.853). The accumulation of deoxyATP by the leukemic cell specimens was correlated best with the activity of ecto-ATPase, less well with cytoplasmic 5'-nucleotidase and deoxyadenosine kinase, and poorly with adenosine deaminase and ecto-5'-nucleotidase. The clinical response to DCF therapy of a patient with T-ALL and another with pre-B-ALL was consistent with the in vitro metabolic response of their cells to DCF and dAdo.
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PMID:Biochemical correlates of the differential sensitivity of subtypes of human leukemia to deoxyadenosine and deoxycoformycin. 628 41


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