Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.3.44 (P-glycoprotein)
 13,344 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A new non-T cell, non-B cell lymphoma cell line, designated IN-1, was established from the ascitic fluid of a patient with non-Hodgkin lymphoma. The IN -1 cells did not show any T cell and B cell immunophenotypes. There were rearrangements of T cell receptor beta- and gamma-chain gene, but no rearrangement of T cell receptor delta-chain gene and immunoglobulin JH gene. Electron microscopically, the cell had numerous pseudopods, mitochondria, vesicles, a conspicuous nucleolus, and scattered heterochromatin at the periphery of the nucleus. They reacted with only OKT9 monoclonal antibody. Molecular analysis revealed that cellular DNA from the IN-1 cells did not hybridize with Bam HI W fragment of EB virus DNA. Cytogenetic analysis showed that the chromosome number of the IN-1 was in the range of 61 -63 whose karyotype analysis demonstrated multiple numerical and structural chromosome changes. The IN-1 cells were resistant to etoposide in comparison with an IC50 of K562 (human chronic myelogenous leukemia). Interestingly, this IN-1 cell possessed 85 KD protein, but not P-glycoprotein, both of which are considered to be multidrug resistance-related proteins.
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PMID:Establishment and characterization of a non-T, non-B cell lymphoma cell line with T cell receptor beta- and gamma-chain gene rearrangement and possessing MRK 20 monoclonal antibody-defined 85KD protein. 196 85

P-glycoprotein (P-gly) is the transmembrane efflux pump responsible for multidrug resistance in tumor cells. The activity of P-gly in mature peripheral lymphocytes is lineage specific, with CD8+ T cells and natural killer (NK) cells expressing high levels as compared to CD4+ T cells and B cells. We have now investigated P-gly activity in immature and mature subsets of mouse thymocytes. Our data indicate that P-gly activity is undetectable in immature CD4-8- and CD4+8+ thymocyte subsets. Among mature thymocytes, P-gly activity is absent in the CD4+ subset but present in the more mature (HSAlow) fraction of CD8+ cells. Furthermore, while thymic CD4-8- T cell receptor (TCR) gamma delta cells have little P-gly activity, a minor subset of CD4-8- or CD4+ TCR alpha beta + thymocytes bearing the NK1.1 surface marker expresses high levels of P-gly activity. Collectively, our results indicate that P-gly activity arises late during thymus development and is expressed in a lineage-specific fashion.
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PMID:Developmentally regulated expression of P-glycoprotein (multidrug resistance) activity in mouse thymocytes. 777 50

A 75-year-old man was admitted to our hospital on June 1st, 1993, because of nasal obstruction, epistaxis, fever, night sweats and weight loss. Examination disclosed a 2-cm white necrotic mass in the nasal septum, and a biopsy disclosed non-Hodgkin's lymphoma, diffuse, mixed-type. Imprint smears showed cytoplasmic azurophilic granules in the tumor cells. Dense granules were demonstrated by electron microscopy. The tumor cells were CD1-2+3-4-7+8-16+56+57-, and T cell receptor genes were in germline configuration. NK activity against K562 was strongly positive. Based on morphologic, phenotypic, immunogenotypic, and cytotoxic findings, the tumor cells seemed to be derived from activated NK cells. Because the tumor cells were positive for the EB virus and CD21 antigen, EB virus seemed to have infected CD21-positive NK cells and transformed them. MDR P-glycoprotein was also positive. This finding may explain why nasal lymphomas are resistant to chemotherapy and have a poor prognosis.
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PMID:[Nasal NK-cell lymphoma]. 807 94

Previous work has established that aging in mice leads to an accumulation of T cells that express high levels of P-glycoprotein, a plasma membrane pump that mediates multiple drug resistance in tumor cells but whose function in normal T cells is still obscure. Pgp+ cells seem to be functionally defective: isolated from the CD4 memory population of young mice, they are unresponsive to T cell receptor-dependent stimuli in tests for proliferation and cytokine production. The proliferative defect can, however, be overcome by exposure to PMA plus the calcium ionophore ionomycin, suggesting that the Pgp+ cells may have a specific defect in calcium signal generation. We show here that Pgp+ T cells, from young or old mice, do indeed show smaller changes in intracellular calcium ion concentration than Pgp- cells, when activated either by Con A, anti-CD3 antibodies, or ionomycin. The difference between Pgp+ and Pgp- cells is apparent even in experiments on isolated CD4 memory T cells from young mice and thus is not simply a consequence of the age-dependent increase in memory cell numbers. Although the molecular basis for the abnormality in calcium signal generation by Pgp+ cells is still uncertain, our data suggest that the effect could be due to inter-subset differences in levels of sorcin, a 22 kDa cytoplasmic protein that is co-expressed with P-glycoprotein in many tumor cells and which binds free calcium ion with high affinity. Sorcin levels are higher in Pgp+ CD4 cells than in Pgp- CD4 cells of young mice and increase with age in CD4 cells, consistent with the hypothesis that sorcin interferes with calcium signals in the age-sensitive Pgp+ T cell subset.
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PMID:Calcium signal abnormalities in murine T lymphocytes that express the multidrug transporter P-glycoprotein. 1022 45