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

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Query: EC:3.6.3.44 (P-glycoprotein)
13,344 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

B5-fixed/paraffin-embedded Jamshidi needle biopsies from 125 multiple myeloma patients were reviewed according to both morphological and immunohistological criteria. At microscopic examination, the following parameters were evaluated: i) grade of malignancy (low = 56; intermediate = 50; high = 19); ii) growth pattern (interstitial +/- sheets/nodules = 90; nodular = 13; packed marrow = 18; sarcomatous = 4); III) histological stage (I = 64; II = 35; III = 26). Comparison of the findings in trephine biopsies and aspirates showed that in 30% of the cases the latter led to an underestimation of the tumor burden. Immunohistochemical determination of Ig easily allowed: i) differential diagnosis from exuberant reactive plasmacytosis; ii) recognition and counting of neoplastic plasma cells; iii) detection of minimal residual disease after treatment. Immunohistochemistry also confirmed phenotypic aberration of neoplastic plasma cells, showing positivity for CD45, EMA, and cytokeratins in 14%, 59%, and 25% of the cases, respectively. Furthermore, it displayed expression of the P-glycoprotein in 4/8 resistant cases. These findings underline that routinely processed Jamshidi needle biopsies can be of great value in the study of patients with multiple myeloma.
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PMID:Histology and immunohistology of bone marrow biopsy in multiple myeloma. 262 92

Twenty-two fresh surgical specimens of human sarcomas (soft tissue and bone) from 20 patients were analyzed by flow cytometry for the expression of drug resistance-related P-glycoprotein (P-gp) and cellular daunorubicin (DNR) accumulation with or without the presence of DNR efflux blockers. Single-cell suspensions prepared from the tumor specimens were analyzed by dual-color flow cytometry after reaction with MRK-16 (anti-P-gp) and anti-CD45 (pan-leukocyte) antibodies. MRK-16 reactivity of tumor cells was evaluated after exclusion of CD45-positive cells by electronic gates. Parallel samples were incubated with DNR alone or in combination with DNR efflux blockers, verapamil (VPL), or dipyridamole (DPD) for determination of cellular DNR accumulation and the effect of the efflux blockers. Extensive heterogeneity was observed in both P-gp expression and DNR accumulation of the tumor specimens examined. Eight of the 22 tumor specimens had significant numbers of P-gp-positive cells. In three of the eight P-gp-positive tumors, cellular DNR accumulation was significantly increased by co-incubation with the efflux blockers VPL or DPD. These results indicate that both quantitative and functional analysis of P-gp expression may be essential in determining the cellular drug resistance phenotype of tumor cells and its correlation with therapeutic outcome.
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PMID:Flow cytometric analysis of P-glycoprotein expression and drug efflux in human soft tissue and bone sarcomas. 929 39

Associations between hematopoietic cells and their microenvironment are central to the development and maintenance of a functional hematopoietic system. It is important, therefore, to identify the surface receptors that mediate adhesive interactions among hematopoietic cells, stromal cells, and extracellular matrix components. In this study, we examined the expression of mRNA transcripts encoding a number of cell adhesion molecules and surface antigens in primitive hematopoietic cells isolated from murine bone marrow and fetal liver. Using a panel of probes, we hybridized a library of globally amplified cDNA prepared by reverse transcriptase-polymerase chain reaction of poly(A)+ mRNA from individual precursors and mature cell populations, representing precisely defined positions within the hematopoietic developmental hierarchy. The panel included probes specific for the CD45, CD34, P-glycoprotein (mdr1), Ly-6A/E (Sca-1), heat stable antigen (CD24), Fc receptor for IgG FcgammaRII (CD32), CD44, CD22, and ICAM-1 (CD54) genes, as well as alphaL (CD11a), alphaM (CD11b), beta2 (CD18), alpha4 (CD49d), alpha5 (CD49e), beta1 (CD29), and beta7 integrin subunit sequences. The data, which revealed stage- and lineage-specific expression patterns, should prove useful in designing future mechanistic studies aimed at elucidating the role played by adhesion receptors in normal and abnormal hematopoiesis.
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PMID:Expression mapping of adhesion receptor genes during differentiation of individual hematopoietic precursors. 932 54

Anthracyclines trigger an apoptotic cell death but their molecular targets are not totally explored. We investigated the apoptotic response of blast cells and lymphocytes from medullary samples of 31 de novo acute leukemia. Mononuclear cells were treated in vitro by therapeutic concentrations of either daunorubicin (DNR) or idarubicin (IDA) for 1 h, washed and cultured for 18 h. A multivariate analysis using flow cytometry and a CD45 gating on lymphocytes and blast cells was performed. DNR and IDA induced a Fas enhancement on both leukemic and normal cells. In blast cells the DEVDases were activated and the caspase 3 was cleaved in relation to phosphatidyl serine exposure, showing a caspase-dependent pathway in anthracycline-induced apoptosis. Apoptotic percentages were always higher for blast cells than for lymphocytes, confirming that anthracycline toxicity mainly affected tumor cells. Moreover, drug-induced apoptosis was not related to spontaneous apoptosis, suggesting that variations in response intensities were due to individual variations of sensitivity rather than to programmed life span time. The apoptotic response of P-glycoprotein-expressing blast cells was not significant, giving biological argument for the poor prognosis of multidrug resistance leukemia. Finally, Fas induction and anthracycline-induced apoptosis on blast cells were significantly higher when a complete remission was achieved, thus shedding light on potential new prognostic factors in acute leukemia.
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PMID:Study of apoptosis-related responses of leukemic blast cells to in vitro anthracycline treatment. 1091 52

Recently, monoclonal antibody(MoAb) therapies which direct at antigens such as CD33, CD45 and GM-CSF receptors on myeloid leukemia cells have been in progress. There are three major MoAb therapies against acute myeloid leukemia(AML), which include unconjugated MoAb, MoAb conjugated with chemotherapy or toxins, and MoAb conjugated with radioisotopes. Gemtuzumab ozogamicin is consisting of an engineered human anti-CD33 antibody linked with the potent anti-tumor antibiotic calicheamicin, which is the most effective for AML. However, recent studies suggested that calicheamicin was also pumped out by multi-drug resistance(MDR) related P-glycoprotein. The combination therapy with MDR modifiers may improve the effect of gemtuzumab ozogamicin.
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PMID:[Antibody directed therapy for leukemia]. 1190 67

Penetrance of anti-retroviral drugs into the CNS depends partly on the activity of P-glycoprotein (P-gp), an ATP-dependent efflux pump involved in restricting entry of lipophilic drugs into the brain. The present study characterizes the patterns of P-gp expression in the brains of AIDS patients and examines its relationship with clinical and neuropathological indicators of HIV encephalitis (HIVE). For this purpose, brain tissue collected at autopsy from 26 subjects with a history of HIV (9 without HIVE; 17 with HIVE) was analyzed. Immunocytochemical staining and Western blot analyses for regional P-gp expression were performed and levels were correlated with neuropathological indicators and with HIV RNA. Double labeling experiments were performed with antibodies against astroglial (GFAP), endothelial (CD31), microglial (CD45) and neuronal (MAP2) cell markers. In the HIVE-negative cases, P-gp immunoreactivity was associated primarily with endothelial cells. HIVE-positive cases showed extensive immunolabeling of astroglial and microglial cells, but relatively less endothelial cell immunolabeling. No neuronal P-gp immunostaining was detected in brain tissue from any cases in the study. In the HIVE-positive cases with extensive astroglial labeling, the most intense immunoreactivity was detected in white matter. A subset of HIVE-positive cases displayed intense P-gp immunostaining of astrocytes closely associated with blood vessels in the cortex. Both the immunocytochemical and Western blot analyses showed a significant correlation between P-gp expression and HIV RNA levels. In conclusion, P-gp immunoreactivity was detected largely in glial cells in tissue from HIVE-positive patients. Furthermore, in HIVE-positive patients, brain viral burden and P-gp levels were significantly higher than those in HIVE-negative patients. Taken together, our data suggest that P-gp may be part of a central pathway mediating viral compartmentalization in the brains of HIV-infected individuals and may play a significant part in HIV disease progression in the brain.
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PMID:Altered P-glycoprotein expression in AIDS patients with HIV encephalitis. 1553 31

The measurement of functional and phenotypic P-glycoprotein by flow cytometry is suitable for cells in suspension, and is particularly appropriate for blood and bone marrow cells. We describe a functional assay for P-glycoprotein using rhodamine 123, an assay for daunorubicin accumulation, and an assay to measure P-glycoprotein levels using the MRK16 antibody. Our protocols include the use of an anti-CD45 antibody for the identification of leukemic blasts. The protocols described in this chapter were designed for use in studies accompanying UK Medical Research Council Trials of patients with Acute Myeloid Leukaemia and High Risk Myelodysplastic Syndrome (>10% blasts). These assays are performed in more than one UK Centre, and hence each assay has been subjected to rigorous reproducibility testing.
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PMID:Flow cytometric measurement of functional and phenotypic P-glycoprotein. 1591 79

Phosphatidylserine (PS) exposure is normally associated with apoptosis and the removal of dying cells. We observed that PS is exposed constitutively at high levels on T lymphocytes that express low levels of the transmembrane tyrosine phosphatase CD45RB. CD45 was shown to be a negative regulator of PS translocation in response to various signals, including activation of the ATP receptor P2X(7). Changes in PS distribution were shown to modulate several membrane activities: Ca(2+) and Na(+) uptake through the P2X(7) cation channel itself; P2X(7)-stimulated shedding of the homing receptor CD62L; and reversal of activity of the multidrug transporter P-glycoprotein. The data identify a role for PS distribution changes in signal transduction, rapidly modulating the activities of several membrane proteins. This seems to be an all-or-none effect, coordinating the activity of most or all the molecules of a target protein in each cell. The data also suggest a new approach to circumventing multidrug resistance.
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PMID:Membrane phosphatidylserine distribution as a non-apoptotic signalling mechanism in lymphocytes. 1602 5

Human brain tissue is a valuable source of material for research. It is often stored indefinitely in formalin at room temperature which may weaken the immunolabeling with formalin-sensitive antibodies. The present study found that a novel protocol that combined citrate and formic acid pre-treatments with the catalyzed signal amplification (CSA) system was able to recover the lost or weakened immunolabeling with the formalin-sensitive antibodies, anti-CD34, anti-caveolin, anti-P-glycoprotein, anti-neuronal nuclei, anti-parvalbumin, anti-human leukocyte antigen, anti-CD45, anti-CD68 and anti-connexin 43, in post-mortem, human brain tissue that was stored in formalin for up to 10 years at room temperature. Recovered immunolabeling in long-fixed tissue resembled immunolabeling observed in tissue that was fixed for a shorter duration between 6 and 49 days. The findings from this study highlight the importance of testing antibodies for formalin fixation effect prior to studies, especially if long-fixed tissue is used, to enable immunolabeling to be more accurately interpreted. Importantly, this study provides a method of overcoming formalin-masking of antigens in long-fixed human tissue, thus allowing essential immunohistochemical studies to be undertaken using precious human tissue.
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PMID:Immunolabeling recovery in archival, post-mortem, human brain tissue using modified antigen retrieval and the catalyzed signal amplification system. 2043 66

Aggressive natural killer-cell leukaemia (ANKL) is a rare type of disease with fulminant course and poor outcome. The disease is more prevalent among Asians than in other ethnic groups and shows strong association with Epstein-Barr virus (EBV) and P-glycoprotein (P-gp) expression associated with multidrug resistance. Here we present a case of a 47 year old Caucasian female with a prior medical history of azathioprine treated ulcerative colitis who developed EBV-negative form of ANKL. The patient presented with hepatosplenomegaly, fever and nausea with peripheral blood and bone marrow infiltration with up to 70% of atypical lymphoid cells positive for cCD3, CD2, CD7, CD56, CD38, CD45, TIA1 and granzyme B, and negative for sCD3, CD4, CD5, CD8, CD34 and CD123 indicative of ANKL. Neoplastic CD56(+) NK-cells showed high level of P-glycoprotein expression and activity, but also strong expression of phosphorylated extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) MAP kinase. The patient was treated with an intensive polychemotherapy regimen designed for treatment of acute lymphoblastic leukaemia, but one month after admission developed sepsis, coma and died of cardiorespiratory arrest. We present additional evidence that, except for the immunophenotype, leukaemic NK-cells resemble normal NK-cells in terms of P-gp functional capacity and expression of phosphorylated ERK1/2 signalling molecule. In that sense drugs that block P-glycoprotein activity and activated signalling pathways might represent new means for targeted therapy.
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PMID:Epstein-Barr virus-negative aggressive natural killer-cell leukaemia with high P-glycoprotein activity and phosphorylated extracellular signal-regulated protein kinases 1 and 2. 2308 5


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