Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023467 (acute myeloid leukemia)
 35,200 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The role of LRP in clinical drug resistance in acute myeloid leukemia (AML) is controversial. We therefore compared multiple assays, including RT-PCR, immunocytochemistry (ICC) and flow cytometry (FC), in 10 cell lines and in 47 fresh and thawed AML cells in order to validate and to quantitate measures for LRP phenotype detection. We also compared different ways of expressing the results. Lastly, in cell lines, we analyzed the 50% lethal concentration (LC50), by MTT assay, of cisplatin which could estimate the functionality of LRP. The reproducibility of LRP detection measured by RT-PCR, ICC and FC was good. In the same way, within the same technique, there was good correlation between the different methods of expressing the results of LRP level. Therefore, the discrepancies noted with the three techniques used were neither a problem of reproducibility nor a problem of results expression. On the other hand, there was only a correlation between ICC and FC, and no correlation between RT-PCR and LRP protein detection techniques. Therefore, RT-PCR is probably not the optimal technique for LRP detection. We have shown in 10 cell lines a higher correlation between FC and LC50 of cisplatin than between ICC and LC50 of cisplatin and no correlation between RT-PCR and LC50 of cisplatin. For five patients, there was a dissociation between ICC and FC. Four patients were positive by FC and negative by ICC and only one patient was negative by FC and positive by ICC. Therefore, if in vitro resistance to cisplatin represents the functionality of LRP, we recommend the use of FC rather than ICC to detect LRP expression. Besides the measurement of LRP as a diagnostic tool in the evaluation of resistance to chemotherapy in patients with AML, we urgently need to establish a functional test in order to assess LRP activity.
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PMID:Lung resistance protein (LRP) gene expression in adult acute myeloid leukemia: a critical evaluation by three techniques. 973 84

The ribonucleotide reductase inhibitors hydroxyurea (HU), arabinosyl-2-fluoroadenine (F-Ara-A) and 2-chlorodeoxyadenosine (2-CdA) and the antisignalling drugs all-trans retinoic acid (ATRA), staurosporine and quercetin have been reported to enhance the cytotoxicity of 1-beta-D-arabinofuranosylcytosine (ara-C). We tested the hypothesis that the ara-C-sensitising potency of the antisignalling agents is equipotent with that of the ribonucleotide inhibitors. The cytotoxicity, determined by the 3-(4,5 dimethylthiazol-2-yl-)5 diphenyltetrazolium bromide (MTT) assay, of combinations of ara-C with the agents named above was compared in the leukaemia cell lines HL-60, ara-C-resistant HL-60 (HL-60/ara-C) and U937. Furthermore, a range of protein tyrosine kinase inhibitors, genistein, CGP 52411, tyrphostin A48 and nordihydroguaiaretic acid (NDGA), for which ara-C-sensitisation has hitherto not been described, were included in the study. All three cell types acquired increased sensitivity to ara-C when co-incubated with HU or ATRA, but their ara-C sensitivity was not affected by quercetin or genistein. 2-CdA, CGP 52411, tyrphostin A48, staurosporine and NDGA were active as sensitisers against ara-C in HL-60 cells, CGP 52411 and tyrphostin A48 also in HL-60/ara-C cells, and 2-CdA, staurosporine and NDGA also in U937 cells. F-Ara-A increased ara-C toxicity in HL-60/ara-C and U937 cells. To address the mechanism of the observed sensitisation, the influence of agents with ara-C-sensitising properties on ara-C-induced apoptosis was investigated in HL-60 cells as measured by cell shrinkage, DNA loss and DNA fragmentation. HU, ATRA, tyrphostin A48 and NDGA augmented apoptosis induced by ara-C as assessed by all three indicators. CGP 52411 decreased the effect of ara-C on apoptotic indicators after incubation for 4 h, but not after 12 h. The results suggest that ATRA, CGP 52411, tyrphostin A48, staurosporine and NDGA may be suitable alternatives to the clinically applied ribonucleotide reductase inhibitors as modifiers of ara-C cytotoxicity in the treatment of acute myeloid leukaemia.
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PMID:Augmentation of 1-beta-D-arabinofuranosylcytosine (Ara-C) cytotoxicity in leukaemia cells by co-administration with antisignalling drugs. 979 4

Expression of P-glycoprotein (Pgp), the drug efflux pump which mediates multidrug resistance (MDR), has been widely reported in chronic lymphocytic leukaemia (CLL) and improved accumulation of daunorubicin has been reported using the MDR reversing agent cyclosporin A (CSA). We have investigated the effects on cell kill of the addition of CSA and its analogue PSC 833 to daunorubicin, doxorubicin, idarubicin, mitozantrone and fludarabine in samples from 51 patients with CLL using an MTT [3(4,5-dimethylthaizol-2-yl)-2,5-diphenyltetrazolium bromide] assay. Pgp expression was assessed by immunocytochemistry using the JSB-1 monoclonal antibody. Of the 51 samples, 10 (20%) were Pgp positive and all of these samples were from treated patients. With the exception of mitozantrone, the addition of CSA and PSC 833 to cytotoxic agents failed to significantly improve cytotoxicity, even in the Pgp positive group. With mitozantrone significant responses were seen in both Pgp positive and negative groups suggesting that the responses were due to direct cytotoxicity of the cytotoxic-modifier combination rather than reversal of MDR. Both CSA and PSC 833 showed significant direct cytotoxicity (P = 0.004 and 0.04 for PSC 833 at 1000 ng/ml and 500 ng/ml respectively; P < 0.001 for both concentrations of CSA). The responses were disappointing compared to the highly significant improvements in cytotoxicity seen using cells from the Pgp positive CEM VLB 100 acute myeloid leukaemia cell line, and it was not possible to demonstrate the superiority of PSC 833 over CSA which is also seen in cell lines. Our data do not support a role for Pgp modifiers in CLL. Further studies using larger numbers of Pgp positive CLL cells and higher doses of PSC 833 would be useful.
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PMID:Effect on cell kill of addition of multidrug resistance modifiers cyclosporin A and PSC 833 to cytotoxic agents in chronic lymphocytic leukaemia. 993 32

Two proteins that have been correlated with the occurrence of multidrug resistance in acute myeloid leukemia (AML) are P-glycoprotein (Pgp) and the major vault protein (Mvp/LRP). With the purpose of further quantifying the potential contributions of Pgp-mediated drug efflux and Mvp/LRP to drug resistance in AML we have investigated whether the transport function of Pgp and the expression of Mvp/LRP correlated with the accumulation of daunorubicin (DNR) and the in vitro resistance to DNR cytotoxicity (LC50 by MTT assay) in AML cells. In de novo adult AML, the steady-state DNR accumulation (in pmol/10(6) cells) correlated with Pgp activity or expression, whereas the LC50 for DNR did not correlate with Pgp activity (measured as the modulation of rhodamine 123 or DNR accumulation by the Pgp inhibitor PSC833) or Pgp expression (measured by flow cytometry with the MRK-16 antibody). The contribution of MRP1 expression to a reduced DNR accumulation seems minor compared to Pgp. In addition, the modulation of the DNR LC50 by PSC833 did not correlate with Pgp protein or activity. The steady-state DNR accumulation showed no correlation with the DNR LC50. The Mvp/LRP expression (immunocytochemical staining) did neither correlate with DNR accumulation nor with the DNR LC50. A significant negative correlation was seen between the Mvp/LRP immunocytochemical staining and Pgp activity, indicating that both markers define (partially) different populations. In conclusion, it is shown that Pgp function, but not Mvp/LRP or MRP1 expression correlate with a low steady-state DNR accumulation in de novo AML. The Pgp activity does, however, not predict the DNR sensitivity in AML measured as in vitro DNR LC50 with an MTT-based assay. The reason for that seems to be that a low DNR accumulation may not be the most important factor in determining the LC50. While the clinical usefulness of these drug resistance tests remains to be proven they do not seem to provide as yet a straightforward explanation for the major cause(s) of clinical chemotherapy failure.
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PMID:Do P-glycoprotein and major vault protein (MVP/LRP) expression correlate with in vitro daunorubicin resistance in acute myeloid leukemia? 1048 3

In ninety-three cases of newly diagnosed acute myeloid leukaemia (AML) we investigated the importance to short- and long term clinical outcome of the in vitro short term leukaemia cell survival as measured by a 4-day MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide)-assay. In 67 patients treated by intravenous remission induction therapy we found that patients who after the first induction cycle or after induction therapy overall achieved a complete remission (CR) had leukaemia cells with significantly lower in vitro cell survival ability than cells of non-responders (p = 0.02 and 0.06, respectively). These relations remained statistically significant in subsequent multivariate analyses. Likewise, a favourable effect of low in vitro leukaemia cell survival on overall survival of the patients was detected in the (largest) subgroup of adult patients treated uniformly by the same remission induction regimen as well as in all patients. However, in the 44 patients, who achieved CR, the in vitro leukaemia cell survival did not show significance to remission duration or time to first relapse. Furthermore, the leukaemia cell survival (MTT-assay) did not to correlate with the Bcl-2 expression level (quantitative flow cytometry) of the leukaemia cells (r = 0.18, n = 34, p = 0.32). In addition, in a cell line model employing the growth factor dependent MO7 human AML cell line, growth factor withdrawal was associated with rapid onset of cellular apoptosis as evaluated by morphology, occurrence of a subG1 peak in DNA histograms, and loss of cellular activity in the MTT-assay. In contrast, a more moderate decline in Bcl-2 expression and gradual loss of ability to exclude the trypan blue dye was seen in the leukaemia cells in response to growth factor withdrawal. We conclude, that the MTT-assay provides a simple and sensitive method for measuring in vitro cell survival. The differences in leukaemia cell survival seen in AML may well be clinically relevant and may help to provide a better understanding of clinical drug resistance.
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PMID:Relevance of in vitro leukaemia cell survival to short- and long term clinical outcome in AML. 1003 30

Expression of three major classes of glutathione S-transferases (GSTs), i.e. alpha, mu and pi class, P-glycoprotein (P-gp) and multidrug resistance-associated protein (MRP) were studied in childhood acute lymphoblastic leukaemia (ALL), acute myeloid leukaemia (AML) and normal peripheral blood lymphocytes by flow cytometry. In vitro cytotoxicity of 4-hydroxy-ifosfamide (IFOS), daunorubicin (DNR) and prednisolone (PRED) was assessed by the MTT assay. Expression of alpha, mu and pi class GST did not significantly differ between leukaemic cells from 100 initial and 14 unrelated relapse ALL patients (GSTalpha P=026; GSTmu P=O009; GSTpi P=0.13). The expression of GSTalpha (1.4-fold, P=0.0004), GSTpi (13-fold, P = 0001) and to a lesser extent also GSTmu (1.1-fold, P=0.03) was higher in ALL compared with normal peripheral blood lymphocytes. Expression of GSTmu and GST7pi was significantly higher in 18 AML compared with 100 ALL patients at initial diagnosis (respectively 1.3-fold, P=0.0005 and 2-fold, P<0.0001). In contrast, GSTalpha was median 2-fold lower expressed in the AML samples (P< 0.0001). Expression levels of alpha, mu and pi class GSTs were not related to the degree of resistance to IFOS, DNR and PRED nor to immunophenotype, white blood cell count or age at presentation of childhood ALL. One exception was a remarkably low expression of GSTalpha in IFOS-sensitive samples compared with a heterogenous expression in IFOS-resistant samples (P= 0.02). Expression of GSTpi, but not of GSTalpha or GSTmu, weakly correlated with the expression of MRP (Rs 0.36, P = 0.002, n = 74) but not with P-gp. However, a high expression of both GSTpi and MRP was not associated with in vitro resistance to IFOS, DNR or PRED. The present data suggest that expression of GSTs is not linked to the degree of resistance to IFOS, DNR and PRED or clinical risk factors in childhood ALL. Whether the high expression of GSTmu and GSTpi in AML cells contributes to the relative resistance to IFOS, DNR and PRED compared with ALL samples (P < or = 0.0001) warrants further study.
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PMID:Different expression of glutathione S-transferase alpha, mu and pi in childhood acute lymphoblastic and myeloid leukaemia. 1005 Jul 15

A new myeloid cell line, MTT-95, was established from the bone marrow of a patient with acute myelogenous leukemia (AML, M7). MTT-95 cells differentiate into mature basophilic cells in culture medium with no chemical component or cytokine. Surface phenotypes were as follows: CD11b 79.3%, CD13 92.4%, CD33 99.8%, CD34 87.9%, CD41a 77.6% and HLA-DR 0.3%. MTT-95 cells were strongly positive for glycoprotein IIb/IIIa by immunohistochemical staining and revealed metachromatic granules. MTT-95 cells seem to possess characteristics of both megakaryocytes and basophils. These findings suggest that MTT-95 cells are basophil progenitors. MTT-95 cells might be useful in the study not only of the biological aspects of basophils, but also of the diversities of AML (M7).
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PMID:Establishment of a new cell line (MTT-95) showing basophilic differentiation from the bone marrow of a patient with acute myelogenous leukemia (M7). 1035 25

The importance of P-glycoprotein (P-gp) in AML has been well documented. Resistance to the anthracyclines can be overcome by several agents including Cyclosporin A (CsA), PSC833 and GF120918. We describe an investigation into the expression, using MRK16 and UIC2, and function of P-gp using daunorubicin with and without modulators by flow cytometric analysis on previously frozen blast cells from 27 patients with primary or secondary AML. We compared this with the in vitro chemosensitivity, using the MTT assay, of fresh blast cells from the same patients. Whilst we found a correlation between P-gp function using CsA and GF120918 and expression using MRK16 (p < 0.05) and (p < 0.02) respectively, we were unable to find any overall correlation between expression and function of P-gp with either in vitro sensitivity to the anthracyclines, previous treatment, or 1 degree or 2 degrees disease. However it was possible to identify individual patients whose cells exhibited P-gp expression and function teamed with in vitro resistance to, and modification of, the anthracyclines. Furthermore, it is possible to identify which modulator had the greatest effect. The fact that we obtained higher indications of resistance reversal using the MTT assay along with finding P-gp expression and function in patients sensitive to the anthracyclines, suggests studies of P-gp should be teemed with chemosensitivity testing to identify specific patients who will benefit.
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PMID:Comparison of P-glycoprotein expression and function with in vitro sensitivity to anthracyclines in AML. 1050 Jul 77

Drug resistant cells often have an increased capacity to repair their DNA after damage by cytotoxic agents. Aphidicolin can inhibit this DNA repair. We describe a study of the effect of aphidicolin to modulate the sensitivity to cytotoxic drugs of blast cells from 13 patients with AML, 11 with de novo disease on presentation and 2 secondary to MDS. Three patients had relapsed following previous therapy and samples were received from 1 patient both on presentation and relapse. Blast cells were exposed to anthracyclines, antimetabolites or etoposide +/- aphidicolin (15 microM) for 48 hours. The MTT assay was used to measure cell survival and the LC50 (concentration of drug required for 50% cell kill) was calculated. Overall, there was a significant increase in sensitivity to ara-C on co-incubation with aphidicolin in 12/14 samples (p = 0.007). The median increase in sensitivity was 3.88-fold (range 1.26- to 80-fold). Interestingly, when patients were grouped according to in vitro sensitivity to ara-C, cells from resistant patients demonstrated the greatest increase in sensitivity (median 14-fold compared to 2-fold for the sensitive group, p = 0.02). Despite the documented evidence for altered DNA repair as a mechanism of resistance to the topoisomerase II inhibitors, we found no significant increase in sensitivity to daunorubicin, doxorubicin or etoposide on co-incubation with aphidicolin. Nevertheless, we believe the unparalleled modulation of ara-C warrants further investigation.
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PMID:Aphidicolin markedly increases the in vitro sensitivity to ara-C of blast cells from patients with AML. 1050 Aug 35

Thirty-five samples of bone marrow (BM) from 17 patients (pts) with ALL and 18 pts with AML (aged 9 m-20 yrs, median 7.7 yrs) were obtained. Using MTT-assay the sensitivity of LB to Ara-C, VP-16, DOX, G(GM)-CSF and their combinations was measured. LC50 was higher in pts with AML than with ALL: to Ara-C 1.94-fold (p < 0.05), to VP-16 1.62-fold (p = 0.2), to DOX 3.9-fold (p < 0.05). Incubation with G-CSF increased the viability of ALL and AML LB--104.3% and 104.1% respectively (the viability of leukemic cells without CSF accepted as 100%). Incubation with GM-CSF decreased the viability of ALL LB (96.5%) and increased the viability of AML LB (139.1%) (p = 0.08). Combining Ara-C with G- or GM-CSF resulted in equal or increased LC50 (compared with LC50 of Ara-C alone) in 100% cases of AML. For ALL: LC50 of "Ara-C+G-CSF" was equal or increased in 63.6% cases; LC50 of "Ara-C+GM-CSF"-in 62.5%. For VP-16 and DOX all pts (ALL, AML) except two had equal or increased LC50 of "CH+CSF" (compared with LC50 of CH alone). These data show: 1) AML LB were less sensitive to the investigated CH than ALL LB. 2) The LC50 of "CH+CSF" was equal or increased compared to the LC50 of CH for the absolute majority of cases with VP-16 and DOX. The same results were obtained with AML and in about 60% cases of ALL. The effect of the increasing of cytototoxity of CH in presence of CSF probably exists mostly at higher concentrations of CH than those that can be achieved in clinical practice.
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PMID:Effects of CSFS and their combinations with chemotherapeutic agents (CH) on leukemic blasts (LB) in children (MTT-assay). 1050 Aug 38


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