Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Most adult patients with acute non-lymphoblastic leukaemia (ANLL) relapse with drug resistance. Overexpression of a plasma membrane protein, P-glycoprotein, correlates with multidrug resistance in human and animal cell lines. We have detected a multidrug resistance phenotype in two patients with drug resistant ANLL by an immunocytochemical assay using a monoclonal antibody to P-glycoprotein. Sequential analysis of peripheral blood samples from both patients showed a progressive increase in both the intensity of staining and the proportion of leukaemic cells that bound antibody as the disease progressed. The assay is simple, and may have prognostic and therapeutic implications.
 ...
PMID:Detection of a multidrug resistant phenotype in acute non-lymphoblastic leukaemia. 287 73

We have examined the expression of P-glycoprotein in clinical leukemic cell samples by using a monoclonal antibody (MRK16) against P-glycoprotein. We found that leukemia cells isolated from 3 out of 6 patients with blast crisis of chronic myelogenous leukemia were reactive to MRK16. These 3 cell lines expressed high levels of mdr1 mRNA, which codes for P-glycoprotein. The present result indicates that the clinically refractory state of the tumor may be predicted in part by determining P-glycoprotein expression using the monoclonal antibody against P-glycoprotein, and the mdr1 probe.
 ...
PMID:Detection of multidrug resistance markers, P-glycoprotein and mdr1 mRNA, in human leukemia cells. 289 23

Cloned lines of Adriamycin (ADR)-sensitive and -resistant P388 leukemia have been established, including P388/ADR/3 and P388/ADR/7 that are 5- and 10-fold more resistant than the cloned sensitive cell line P388/4 (Cancer Res., 46: 2978, 1986). A time course of ADR-induced DNA double-strand breaks revealed that in sensitive P388/4 cells, evidence of DNA repair was noted 4 h after removal of drug, whereas in resistant clone 3 and 7 cells repair was observed 1 h after drug removal. The earlier onset of DNA repair was statistically significant (p = 0.0154 for clone 3 cells, and p = 0.0009 for clone 7 cells). By contrast, once the repair process was initiated, the rate of repair was similar for all three cell lines. The level of glutathione transferase activity was determined in whole cell extracts. Enzyme activity (mean +/- SE) in sensitive cells was 9.49 +/- 1.00 nmol/min/mg protein, that in resistant clone 3 cells was 13.36 +/- 1.03 nmol/min/mg, and that in clone 7 cells was 13.96 +/- 1.44 nmol/min/mg; the 1.44-fold increase in enzyme activity in resistant cells was statistically significant (p = 0.01). Further evidence of induction of glutathione transferase was provided by Northern blot analysis using a 32P-labeled cDNA for an anionic glutathione transferase, which demonstrated approximately a twofold increase in mRNA in resistant clone 7 cells. Western blot analysis with a polyvalent antibody against anionic glutathione transferase also revealed a proportionate increase in gene product in resistant cells. Dose-survival studies showed that ADR-resistant cells were cross-resistant to actinomycin D, daunorubicin, mitoxantrone, colchicine, and etoposide, but not to the alkylating agent melphalan; this finding provided evidence that these cells are multidrug resistant. Using a cDNA probe for P-glycoprotein, a phenotypic marker for multidrug resistance, Northern blot analysis showed an increase in the steady state level of mRNA of approximately twofold in resistant clone 3 and 7 cells. Southern analysis with the same cDNA probe showed no evidence of gene amplification or rearrangement. Western blot analysis with monoclonal C219 antibody demonstrated a distinct increase in P-glycoprotein in resistant cells. Efflux of Adriamycin as measured by the efflux rate constant was identical in all three cell lines. Furthermore, the metabolic inhibitors azide and dinitrophenol did not augment drug uptake in either sensitive or resistant cells. These findings suggest that despite the increase in P-glycoprotein, an active extrusion pump was not operational in these cells.(ABSTRACT TRUNCATED AT 400 WORDS)
 ...
PMID:Multifactorial resistance to adriamycin: relationship of DNA repair, glutathione transferase activity, drug efflux, and P-glycoprotein in cloned cell lines of adriamycin-sensitive and -resistant P388 leukemia. 289 75

Mouse macrophage-like J774.2 cells were selected for resistance to colchicine and examined by molecular/cytogenetic analysis to determine whether the acquisition of the multidrug resistant (mdr) phenotype was associated with specific chromosomal rearrangements. Cytogenetic studies of the J774.2 parental and two colchicine-resistant (CLCR) sublines--J7.Cl-30 (770-fold CLCR) and J7.Cl-100 (2500-fold CLCR)--demonstrated specific numeric and structural karyotypic alterations accompanying the emergence of mdr. The parental cells demonstrated a modal chromosome number of 63, while the modal number of the J7.Cl-30 subline was 53. The most striking difference between the parental and J7.Cl-30 subline was the presence of an average of 60 double minutes (DMs) per cell in the CLCR cells. The 2500-fold resistant J7.Cl-100 subline displayed a modal number of 50, which included structural rearrangements involving chromosomes 2 and 7 and concomitant replacement of DMs by a homogeneously staining region (HSR). Southern blotting analysis demonstrated a approximately 35-fold amplification of P-glycoprotein homologous sequences in the J7.Cl-30 subline and approximately 70-fold amplification in the J7.Cl-100 subline. Chromosomal in situ hybridization localized the amplified P-glycoprotein sequences to DMs (J7.Cl-30) and the HSR (J7.Cl-100) in these CLCR sublines. Our results suggest that CLCR in J774.2 cells results from overexpression of P-glycoprotein via gene amplification which was accompanied by chromosomal evolution from DMs to an HSR.
Leukemia 1988 Jul
PMID:Molecular/cytogenetic alterations accompanying the development of multidrug resistance in the J774.2 murine cell line. 289 84

Two monoclonal antibodies, MRK16 and MRK20 that recognize P-glycoprotein and P-85 kd protein on the surface of adriamycin (ADM) resistant cells, respectively, were tested for the reactivity with 40 cultured leukemia/lymphoma cell lines. F(ab')2 form is essential to avoid false reaction through Fc gamma-R. Drug sensitivity of 19 representative cell lines were also examined in vitro. From this study, it was found that these cell lines were classified into 4 groups. Group 1 (4 cell lines) was insensitive to ADM, mitoxantron (MXT), etoposide (VP-16) and vincristine (VCR), and reactive to MRK16 and MRL20. Group II (1 cell line) was insensitive to the 4 drugs, but not reactive to both antibodies. Group III (3 cell lines) was insensitive to ADM, MXT and VP-16, but sensitive to VCR, and reactive to MRK20, but not to MRK16. Group IV (all other cell lines) was sensitive to these drugs, and not reactive to both antibodies. From these results, MRK16 detects P-glycoprotein-associated multidrug resistance (MDR), while MRK20 does P 85-kd-associated another type MDR (cross resistance to ADM, MXT and VP-16, but not to VCR). MRK20 reacted with monocytes, but MRK16 did not with any WBC type. One hundred and ninety eight clinical samples obtained from blood cancer were tested for the reactivity with MRK16. MRK16 did not react with any of 98 samples obtained before treatment, but did with 9 of 100 obtained at relapse or refractory stage after chemotherapy. The results indicate that MRK16 is useful to detect drug resistance phenotype of leukemia and lymphoma.
 ...
PMID:[Detection of multidrug resistant phenotype in leukemia and lymphoma by monoclonal antibodies]. 290 32

The lipophilic antitumor alkaloid acronycine (ACRO) was solubilized in the cosolvent system used for etoposide. ACRO in this etoposide diluent (VPD) was found to be cytotoxic (less than or equal to 50% colony formation in soft agar) in fresh human tumors from patients with renal cell cancer, ovarian cancer, uterine cancer, and metastatic tumors of unknown primary. In P-glycoprotein-positive, multidrug-resistant (MDR) cell lines, ACRO in VPD was active in MDR Chinese hamster ovary cells but not against MDR L1210 murine leukemia cells, 8226 human myeloma cells, or human CCRF-CEM lymphoblasts. In mice, ACRO in VPD was active in two solid tumor models and an i.p. MOPC-315 plasmacytoma model. ACRO i.p. in 10% VPD (v/v%) produced significant tumor growth delays in (a) nude mice bearing human MCF-7 breast cancer xenografts and (b) C57BL mice bearing colon 38 tumor. In MOPC-315-bearing mice, a single i.p. ACRO dose of 25 mg/kg was as effective as melphalan (15 mg/kg) at prolonging life span. Finally, ACRO pharmacokinetics was evaluated in mice given single 25-mg/kg doses i.p. or p.o. The oral bioavailability of an ACRO solution in VPD was only 50% but both i.p. and p.o. regimens achieved plasma levels greater than 1.0 micrograms/ml. The plasma half-life was just under 2 h. These results show that parenteral ACRO in VPD comprises a cytotoxic antitumor agent with improved bioavailability over p.o. administration. ACRO is active in vitro against several human solid tumors but is cross-resistant in 3 of 4 MDR tumor cell lines. The prior clinical activity of p.o. ACRO in myeloma and the new results in MOPC-315 plasmacytomas in mice suggest that ACRO in VPD could have activity against human multiple myeloma.
 ...
PMID:Antitumor activity and murine pharmacokinetics of parenteral acronycine. 291 Apr 53

Intrinsic and acquired multidrug resistance (MDR) is an important problem in cancer therapy. MDR in human KB carcinoma cells selected for resistance to colchicine, vinblastine, or doxorubicin (former generic name adriamycin) is associated with overexpression of the "MDR1" gene, which encodes P-glycoprotein. We previously have isolated an overlapping set of cDNA clones for the human MDR1 gene from multidrug-resistant KB cells. Here we report the construction of a full-length cDNA for the human MDR1 gene and show that this reconstructed cDNA, when inserted into a retroviral expression vector containing the long terminal repeats of Moloney leukemia virus or Harvey sarcoma virus, functions in mouse NIH 3T3 and human KB cells to confer the complete multidrug-resistance phenotype. These results suggest that the human MDR1 gene may be used as a positive selectable marker to introduce genes into human cells and to transform human cells to multidrug resistance without introducing nonhuman antigens.
 ...
PMID:Expression of a full-length cDNA for the human "MDR1" gene confers resistance to colchicine, doxorubicin, and vinblastine. 347 46

Expression of the multidrug resistance efflux pump P-glycoprotein (Pgp) was measured in a series of AML patients using two flow cytometry methods. Transport function was assessed by measuring the modulating effect of the Pgp inhibitor cyclosporin A (CsA) on the cellular accumulation of daunorubicin, and Pgp antigen expression by surface immunofluorescence using the MRK-16 antibody. Both methods showed a wide range of values for Pgp expression between individual patients, but in contrast to a series of cell lines expressing Pgp there was no correlation between antigen expression and transport function in the clinical samples. As previously reported for chronic lymphocytic leukemia (CLL), pretreatment with neuraminidase markedly improved MRK-16 staining in some cases, indicating that abnormal glycosylation can cause epitope masking in AML blasts. Because experience with cell lines shows that Pgp expression is a continuous variable which correlates with the level of drug resistance, rather than the 'positive' or 'negative' which are frequently reported by clinical flow cytometry laboratories, we used a calibration procedure to estimate the actual number of Pgp molecules expressed in the AML samples. Despite the additional refinements of neuraminidase treatment and antigen quantification, the correlation between Pgp antigen expression and daunorubicin accumulation remained extremely weak (r = 0.11; P = 0.63). It is suggested that the assay for transport function can detect molecules that affect daunorubicin accumulation but are antigenically distinct from classical P-glycoprotein. Heterogeneity of multidrug resistance efflux pumps might in part explain the relatively weak prognostic significance of immunofluorescence detection of Pgp in AML patients.
Leukemia 1995 Nov
PMID:Discordant P-glycoprotein antigen expression and transport function in acute myeloid leukemia. 747 79

Anti-B4-blocked ricin (anti-B4-bR) is an immunotoxin directed against CD19-positive cells that is currently being tested in several B-cell leukemia/lymphoma clinical trials. To explore the possibility of using anti-B4-bR in combination with chemotherapy protocols, we investigated the in vitro and in vivo cytotoxic effects of combining it with doxorubicin or etoposide using the lymphoma cell line Namalwa and a P-glycoprotein-expressing cell line, Namalwa/mdr-1, obtained by retroviral infection of Namalwa cells with the mdr-1 gene. Namalwa/mdr-1 cells were slightly more sensitive to anti-B4-bR than Namalwa cells; IC37 values were approximately 4 pmol/L and 8 pmol/L, respectively. When anti-B4-bR was combined simultaneously with doxorubicin or etoposide, additive to supra-additive killing of Namalwa and Namalwa/mdr-1 cells was observed. In xenografts of Namalwa/mdr-1 cells in severe combined immunodeficiency (SCID) mice, doxorubicin and etoposide at their maximum tolerated doses (3 mg/kg x 3 or 15 mg/kg x 3) showed no therapeutic effect. However, treatment with 5 daily bolus injections of anti-B4-bR (50 micrograms/kg) followed by treatment with doxorubicin or etoposide significantly increased the life span of the mice by 129% and 115%, respectively. After treatment with anti-B4-bR, the Namalwa/mdr-1 population expressed lower levels of P-glycoprotein, and this decrease may account for the synergistic action of the drug combinations. These results suggest that anti-B4-bR could be used to good effect in combination with current treatment regimens and further hint at a promising role for this immunotoxin in treatment of disease at the minimal residual disease stage, where cells may be resistant to chemotherapy.
 ...
PMID:Anti-B4-blocked ricin synergizes with doxorubicin and etoposide on multidrug-resistant and drug-sensitive tumors. 749 89

The intracellular pharmacokinetics and cytotoxicity of idarubicin (IDA), daunorubicin (DNR), and their corresponding C-13 alcohol metabolites, idarubicinol (IDAol) and daunorubicinol (DNRol), were studied in drug-sensitive HL-60/W human leukemia cells, and in two multidrug-resistant (MDR) sublines, HL-60/Vinc (overexpress P-glycoprotein, Pgp) and HL-60/Adr (overexpress multidrug resistance-associated protein, MRP). Intracellular drug accumulation (1 micrograms/mL) and retention were measured by flow cytometry. Mean intracellular steady-state concentration (Css, fluorescence units/cell) and area under the intracellular drug concentration x time curve (AUC, Fl.U/cell.min) were calculated. Relative to the values for the respective drugs in HL-60/W cells, the Css and AUC of IDA were much higher than those of DNR in the MDR cell lines, with Css and AUC of IDAol intermediate between IDA and DNR. In the MDR cell lines, the MDR modulator cyclosporine A (CsA), in concentrations of 0.3 to 30 mumol/L, caused minimal effects on 3-hr IDA accumulation, intermediate enhancement of IDAol accumulation, and greatest enhancement of DNR accumulation. The MDR cell lines were much less resistant to IDA (3- to 16-fold) than to DNR (65- to 117-fold). This difference was not the result of IDA being more potent than DNR, since the sensitivity of HL-60/W cells to IDA differed from their sensitivity to DNR by < 2-fold. The cellular pharmacokinetics and cytotoxicity of IDA in MDR human breast carcinoma cells MCF-7/AdrVp, which overexpress the putative MDR transporter P-95, were far superior to those of DNR, and were comparable to these parameters for IDA in parental MCF-7/W cells. These studies demonstrate that the cellular pharmacology and cytotoxicity of IDA in MDR cell lines that overexpress MRP, Pgp, or P-95 are more advantageous than those of DNR, suggesting that IDA is less susceptible to the transport-mediated MDR mechanism manifested. IDA is not completely invulnerable to MDR, however, since the MDR sublines studied did display a demonstrable level of resistance to IDA, compared with their drug-sensitive counterparts. IDAol, the major plasma metabolite of IDA, demonstrated behavior intermediate between the MDR-susceptible drug DNR and its parent compound, suggesting that its cytotoxic action is subject to transport-mediated cellular defenses.(ABSTRACT TRUNCATED AT 400 WORDS)
 ...
PMID:Susceptibility of idarubicin, daunorubicin, and their C-13 alcohol metabolites to transport-mediated multidrug resistance. 750 71


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