UMLS:C0023418 - FACTA Search

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

Of 4 lines of myelogenous rat leukemias induced by N-nitrosobutylurea (NBU), DBLA-6 was selected as a screening model for antileukemic agents because of the following characteristics: a) High transplantability either by intravenous (i.v.) or intraperitoneal (i.p.) inoculation; b) linear relationship between inoculum size and survival time; c) marked increase of leucocyte counts in the peripheral blood as the tumor progresses after intravenous inoculation. To investigate reliability in its predicting clinical efficacy, its sensitivity to known antileukemics was studied. To determine the effects, a change of leucocyte counts in the peripheral blood together with the prolongation of life span was checked in the following systems; i.v.-i.v. (i.v.-inoculation, i.v.-injection), i.v.-i.p., i.p.-i.p., i.p.-i.v. Fifty percent cure was obtained with Vincristine, Vinblastine, Daunorubicin, 6-Mercaptopurine, and alkylating agent 838D or 864T. The success of treatment was measured by decrease of leucocytes. Methotrexate, cytosine arabinoside (Ara-C), and cyclophosphamide showed only poor effects, and Mitomycin C, L-asparaginase, and Bleomycin were ineffective. In addition, the chemotherapeutic effects of Vincristine and 864 on this leukemia were quite dependend both on the route of drug injection and on the site of tumor inoculation. Subsequently, our studies are being extended to cover the correlation between drug distribution and tumor localization or dissemination.
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PMID:Sensitivity of DBLA-6 leukemia of rats to known antitumor agents in relation to their clinical effects. 116 99

A variant line (CEM-7A) "overproducing" the reduced folate/MTX carrier system was isolated from human CCRF-CEM leukemia cells grown under selective conditions in medium containing 0.25 nM 5-formyl-THF as the sole folate source. This line exhibits a 95-fold increased Vmax for [3H]-MTX influx as compared to parental cells. The values for [3H]-MTX influx Km, efflux t1/2 and structural specificity for other (anti)folate compounds were unchanged. The amount of carrier protein, estimated by NHS-[3H]-MTX affinity labeling, was approximately 30-fold higher in CEM-7A cells than in parental cells. Influx of [3H]-MTX in CEM-7A cells was found to be down-regulated 6-7-fold after preincubation of cells with adenosine, 5-formyl-THF or 5-methyl-THF, but could be prevented exclusively by inhibitors of dihydrofolate reductase. The underlying mechanism(s) of these effects have not as yet been elucidated. A radioiodinated photoaffinity analog of MTX was used to prove the molecular events in carrier-mediated MTX uptake in parental CCRF-CEM cells, CEM-7A cells, and a line exhibiting a MTX-transport defect (CEM-MTX). Specific labeling of an 80-85 kDa membrane protein was observed in parental cells, but not in CEM/MTX cells. Uptake of photoprobe and levels of the 80-85 kDa membrane protein were significantly increased in CEM-7A cells. Due to extensive glycosylation the MW of the carrier protein in human cells seems to be substantially higher than that of its counterpart in murine L1210 leukemia cells (46-48 kDa). Pulse-labeling experiments at 37 degrees C demonstrated that in CEM-7A cells photoprobe uptake proceeds via a specific pathway. The 80-85 kDa membrane protein is involved in the initial binding and translocation of photoprobe, after which a 38 kDa cytosolic protein is responsible for further intracellular distribution. At this time, the combination of photoaffinity labeling techniques and the availability of variant cell lines overexpressing the reduced folate/MTX carrier protein has provided new insights into the MTX transport process in human leukemia cell lines. In the near future this approach should also allow a further elucidation of the regulatory aspects of carrier function.
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PMID:Molecular events in the membrane transport of methotrexate in human CCRF-CEM leukemia cell lines. 132 3

Biotin derivatives of methotrexate (biotin-SS-MTX) and folate (biotin-SS-folate), in which the functional components are joined by a dissociable disulfide-containing spacer, have been synthesized, purified by DEAE-Trisacryl chromatography, and characterized by HPLC, elemental analysis and mass spectrometry. These compounds provide a convenient means for the single-step purification of the folate transporters from L1210 cells. Parental L1210 murine leukemia cells, which contain only the microM transporter (the reduced folate/MTX transport protein) were treated with the N-hydroxysulfosuccinimide ester of biotin-SS-MTX, and a detergent extract of the plasma membranes was exposed to streptavidin-agarose beads to adsorb the labeled protein. Dithiothreitol cleavage of the disulfide linkage released the transporter, which migrated as a well-defined component (43 kDa) on SDS-PAGE gels; no other proteins were present. An L1210 subline (JF), obtained by adapting cells to grow on nanomolar concentrations of folate, contains both the microM transporter and the nM transporter (high-affinity folate binding protein). When these cells were treated with the N-hydroxysulfosuccimide ester of biotin-SS-folate and processed as described above, analysis on SDS-PAGE gels revealed the presence of two proteins, the microM transporter (43 kDa) and the nM transporter (39 kDa). Both transporters were characterized with respect to amino acid content; blocked N-termini precluded Edman sequencing. Treatment of the nM transporter with peptide:N-glycosidase F produced a smaller component (32 kDa); the microM transporter, conversely, was unchanged by this procedure. When the microM transporter in parental L1210 cells was labeled with fluorescein-MTX and then treated with phosphoinositol-specific phospholipase C (PI-PLC), no change in fluorescence was detected. Alternatively, when the nM transporter in the JF subline was labeled with fluorescein-folate and then treated with PI-PLC, complete loss of fluorescence was observed. These results indicate that the L1210 microM transporter is a non-glycosylated, integral membrane protein, while its nM counterpart is heavily glycosylated and anchored exofacially to the membrane by a glycosylphosphatidylinositol component.
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PMID:Multiple folate transport systems in L1210 cells. 132 5

An episode of transient encephalopathy after the first course of intravenous high-dose methotrexate (HD-MTX; 1000 mg/m2) was observed in a 4-year-old girl with acute lymphoblastic leukemia. The neurological abnormalities took place 5 days after HD-MTX therapy. She experienced complex partial seizure and left hemiparesis, which resolved spontaneously in 5 days. Cranial computed tomographic scan and magnetic resonance imaging showed multiple low-density lesions in bilateral hemispheres. It is well appreciated that neurotoxicity from MTX follows prolonged exposures, often accompanying or following radiation therapy. To our knowledge, however, there have been no reports that such neurological complications developed following a single exposure of HD-MTX in patients with ALL. Follow-up electroencephalograms showed that she had periodic lateralized epileptiform discharges (PLEDS), suggesting functional deafferentation of cortical neurons following HD-MTX. Moreover, the serum and CSF MTX levels following a second low-dose course and her clinical course suggested that she had presumably central nervous system leukemia at the time of HD-MTX therapy, which might have been related to neurological complications. The pathogenesis of MTX-induced neurotoxicity is discussed.
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PMID:Transient encephalopathy following a single exposure of high-dose methotrexate in a child with acute lymphoblastic leukemia. 138 40

We investigated the effect of high dose methotrexate (HDMTX) therapy on plasma hypoxanthine (Hx) and uridine (UR) concentrations in 12 children with acute lymphoblastic leukemia (ALL) or non-Hodgkin lymphoma (NHL). The initial plasma Hx level before the first administration of HDMTX (1 g/m2) was significantly higher in patients (25.5 +/- 17.5 microM) than that in healthy adult controls (4.0 +/- 1.4 microM). By 48 or 72 hours after the beginning of MTX infusion, the Hx concentration had decreased to 7.9 +/- 7.7 microM and 4.7 +/- 4.1 microM, respectively. This decrease of plasma Hx concentration after MTX infusion was also observed with the second course of HDMTX (3 g/m2) therapy. On the other hand, the plasma UR level did not change significantly. The in vitro treatment with 2 microM MTX of hypoxanthine-guanine phosphoribosyltransferase (HGPRT)-deficient mutant cells selected from HL-60 lowered the excretion of Hx into the culture medium. These data suggest a possible new explanation of the synergism of HDMTX and 6-thiopurines, for example 6-mercaptopurine and 6-thioguanine, since plasma Hx is considered to counteract 6-thiopurine toxicity through competition at the level of HGPRT.
Leukemia 1992 Nov
PMID:Effect of high-dose methotrexate on plasma hypoxanthine and uridine levels in patients with acute leukemia or non-Hodgkin lymphoma in childhood. 143 5

Long-term follow-up observations are reported on 427 patients who received one of three different intensified therapies in total therapy study X for acute lymphoblastic leukemia (ALL). In the trial for 'standard-risk' ALL, 154 of 309 patients in complete remission were randomized to receive high-dose methotrexate (HDMTX, 1 g/m2) periodically during the first 72 of 120 weeks of standard continuation therapy with 6-mercaptopurine and oral MTX; the remaining 155 patients received 1800 cGy cranial irradiation and intrathecal MTX, followed by 6-mercaptopurine/MTX therapy interrupted from week 36-71 for substitution of two other pairs of drugs. At 9 years of follow-up, significantly higher proportions of patients in the HDMTX group have maintained complete remissions (64 +/- 7%, SE, vs. 52 +/- 6%, p = 0.03), hematologic remissions (73 +/- 6% vs. 62 +/- 6%, p = 0.03), and testicular remissions (94 +/- 5% vs. 80 +/- 8%, p = 0.03); however, the proportion continuing in central nervous system remission has been lower (84 +/- 5% vs 93 +/- 4%, p = 0.02). In the evaluation of teniposide/cytarabine and delayed cranial irradiation for 'high-risk' ALL, 36 +/- 9% of 101 patients are predicted to be event-free survivors at 9 years. Altogether, 217 (51%) of the 427 patients are event-free survivors after at least 7 years of follow-up (median, 9 years); an additional 75 patients are alive and free of leukemia for a median of 6.4 years after successful remission retrieval therapy, boosting the total number of long-term survivors to 292 (68%). These results establish the efficacy of HDMTX for patients with standard-risk ALL and indicate the potential of teniposide/cytarabine for use in multiagent regimens for patients with high-risk disease. The overall survival figure, 68%, affords a benchmark for other studies assessing long-term outcome in ALL.
Leukemia 1992 Feb
PMID:Impact of three methods of treatment intensification on acute lymphoblastic leukemia in children: long-term results of St Jude total therapy study X. 155 46

The hyperthermia as well as radiation responses of multidrug resistant (CEM/VLB100 with classical MDR and CEM/VM-1 with atypical MDR), methotrexate resistant (CEM/MTX) subclones of CCRF-CEM T-lineage ALL cell line were compared with those of a drug sensitive (CEM-1-3) subclone from the same parent cell line. Also analyzed were the hyperthermia as well as radiation responses of multidrug resistant (HL60/AR) and drug sensitive subclones of the HL60 AML cell line. Notably, the drug resistant subclones of CEM and HL60 were as sensitive to hyperthermia as were the drug sensitive subclones. Importantly, no thermotolerant plateau was observed in the hyperthermia survival curves of the drug resistant subclones, indicating that drug/multidrug resistance is not associated with a greater likelihood of thermal tolerance development during hyperthermia. Similarly, the drug resistant CEM and HL60 subclones were not more radiation resistant than the drug sensitive subclones. Thus, the classical or atypical forms of multidrug resistance or methotrexate resistance of the analyzed leukemic cell lines were not associated with radiation resistance. Furthermore, the radiation survival curves of the drug resistant subclones lacked a distinct initial shoulder and their n values were not greater than those of the drug sensitive subclones, suggesting that multidrug resistance is not associated with an increased ability to repair or accumulate sublethal radiation damage. Our findings provide evidence that there is no apparent association between drug/multidrug resistance and heat or radiation sensitivity of CEM T-lineage ALL or HL60 AML leukemia cells. The results of this study indicate that acquired resistance to methotrexate, vinblastine, vincristine, etoposide, actinomycin-D, adriamycin, or daunomycin, or pleiotropic multidrug resistance do not necessarily confer radiation resistance for human leukemic cells.
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PMID:Radiation and heat sensitivity of human T-lineage acute lymphoblastic leukemia (ALL) and acute myeloblastic leukemia (AML) clones displaying multiple drug resistance (MDR). 157 9

From February 1986 to January 1991 the Pediatric Oncology Group (POG) treated 2404 children or adolescents with acute lymphoblastic leukemia (ALL) on immunophenotype (T-, B-, Pre-B, or Early pre-B-cell), age, and leukocyte count based treatment protocols (ALinC 14, T-cell 3, B-cell and infant leukemia studies). The immunophenotypic subgroups comprised 78.9% B-precursor cell, 15.1% T-cell, 2.0% B-cell, and 4% infant ALL. Patients with B-progenitor cell ALL were stratified by age and leukocyte count and randomized to receive induction therapy comprised of vincristine, prednisone, and asparaginase with triple intrathecal chemotherapy (methotrexate, hydrocortisone, cytarabine), followed by intensification with moderate-dose MTX (Regimen A), moderate-dose MTX plus asparaginase (Regimen B), moderate-dose MTX plus cytarabine given early (Regimen C), or moderate-dose MTX plus cytarabine given over the first 16 months of therapy (Regimen D). Continuation therapy comprised mercaptopurine and methotrexate with vincristine plus prednisone pulses. Central nervous system preventive treatment was continued for two years. Patients with T-cell or B-cell ALL or infants less than 1 yr old were treated on individual very intensive multiagent therapy protocols. The 4-year event-free survival for all patients was 66.4% +/- 2.4%; B-precursor ALL approximately 72%, T-ALL approximately 50%, B-ALL approximately 60%, and infants less than 1 yr old approximately 16.5%. We conclude that about two-thirds of newly diagnosed children with ALL can be cured with this approach which spares the majority of children exposure to alkylating agents, anthracyclines, epipodophylotoxins, and irradiation, diminishing the risks of serious acute and late effects.
Leukemia 1992
PMID:Current results of studies of immunophenotype-, age- and leukocyte-based therapy for children with acute lymphoblastic leukemia. The Pediatric Oncology Group. 157 22

To investigate the effects of mitoxantrone in combination with other anticancer agents, a human T-cell leukemia cell line, MOLT-3, was incubated for 3 days in the presence of two drugs (mitoxantrone and the combined drug) and cell growth inhibition was determined by assay with 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazonium bromide. The effects of drug combinations at doses giving 80% inhibition (ID80) were analyzed by an improved isobologram method. A supra-additive (synergistic) effect was observed for mitoxantrone in combination with amsacrine, cisplatin, or cytosine arabinoside. An additive effect was observed for its combination with bleomycin, doxorubicin, etoposide, 5-fluorouracil, mitomycin C, 6-mercaptopurine, or vincristine. A sub-additive (antagonistic) effect was observed for its combination with methotrexate. These data suggest that mitoxantrone, administered simultaneously with any one of a majority of anticancer agents we studied, is advantageous for cytokilling. Of the anticancer agents tested, amsacrine, cisplatin, and cytosine arabinoside are the most suitable for combination with mitoxantrone, and these combinations are worthy of clinical investigation. Methotrexate in our system is inappropriate for simultaneous administration with mitoxantrone. These data should provide useful information for the establishment of clinical protocols involving mitoxantrone.
Leukemia 1992 May
PMID:Effects of mitoxantrone in combination with other anticancer agents on a human leukemia cell line. 159 9

Resistance to multiple chemotherapeutic agents is a common clinical problem in the treatment of cancer: such resistance may occur in primary therapy or be acquired during treatment. The most commonly used antineoplastic agents in the treatment of disseminated breast cancer are adriamycin, methotrexate and cyclophosphamide. Cell lines selected for resistance to adriamycin often develop cross-resistance to structurally dissimilar antineoplastic drugs with different mechanisms of cytotoxic action; this phenomenon has been called pleiotropic or multidrug resistance (MDR). In vitro models of MDR have shown that this type of resistance is accompanied by a decrease in cellular drug accumulation, mediated by the over-expression of a 170 kD plasma membrane glycoprotein referred to as P170. Glycoprotein P170 is an energy-dependent multidrug efflux pump, whose activity can be inhibited in vitro by a variety of agents including verapamil, quinidine and reserpine. P170 is over-expressed also in some human malignancies, and evidence exists about its role in examples of clinical resistance in vitro. Clinical trials using verapamil, a calcium channel blocker which selectively enhances drug cytotoxicity in MDR cell lines, have been prompted for leukemia and ovarian cancer. In addition other approaches are the subject of current preclinical investigations. Several observations as well the phenomenon of "atypical" MDR in cell lines which do not overexpress P170, suggest that also other factors are involved in multidrug resistance. Qualitative or quantitative changes in the activity of topoisomerases, protein kinase-related systems and glutathione S-transferase, may confer pleiotropic resistance. As the role of these genes and their regulation is clarified, they may also serve as useful targets for pharmacologic intervention in the treatment of drug-resistant human tumors. The mechanisms involved in resistance to methotrexate and cyclophosphamide are less studied, particularly in vivo samples. Methotrexate resistance is probably a complex multifactorial phenomenon; in some cases it is due to an increase in the expression of the drug target dihydrofolate reductase, often as a result of gene amplification, but in other cases a transport defect of the methotrexate or alterations of the activity of different enzymes have been reported. Cyclophosphamide (CP) resistance has been attributed to an increased activity of two different enzymes, glutathione S-transferase, also involved in MDR phenotype, and aldehyde dehydrogenase, which catalyzes inactivation of CP in non cytotoxic metabolites. This paper reviews the current state of our knowledge of chemo-resistance and the utility of available markers to identify potentially resistant tumors in vivo; the strategies that might be used to overcome this phenomenon are also described.
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PMID:Chemoresistance in breast tumors. 168 Jun 89

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